National Library of Energy BETA

Sample records for transportation dot research

  1. NREL: Transportation Research - DOE, DOT Announce Collaboration to Advance

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Smart Transportation Systems DOE, DOT Announce Collaboration to Advance Smart Transportation Systems May 17, 2016 The U.S. Department of Energy (DOE) and U.S. Department of Transportation (DOT) recently announced their collaboration to accelerate research, demonstration, and deployment of innovative transportation and alternative fuel technologies. The agencies made their formal Memorandum of Understanding known at an electric vehicle workshop in Berkeley, California. The initiative will tap

  2. DOT Awards University Transportation Centers $63 Million

    Energy.gov [DOE]

    The U.S. Department of Transportation's (DOT) announced approximately $63 million in grants to 33 University Transportation Centers to advance research and education programs that address critical transportation challenges.

  3. Transportation Research

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    transportation-research TRACC RESEARCH Computational Fluid Dynamics Computational Structural Mechanics Transportation Systems Modeling Transportation Research Current Research Overview The U.S. Department of Transportation (USDOT) has established its only high-performance computing and engineering analysis research facility at Argonne National Laboratory to provide applications support in key areas of applied research and development for the USDOT community. The Transportation Research and

  4. Nontoxic quantum dot research improves solar cells

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Nontoxic quantum dot research improves solar cells Nontoxic quantum dot research improves solar cells Solar cells made with low-cost, nontoxic copper-based quantum dots can achieve unprecedented longevity and efficiency, according to a study by LANL and Sharp Corporation. December 10, 2013 Hunter McDaniel, Los Alamos National Laboratory postdoctoral researcher, works in the laboratory developing next-generation quantum dots that could revolutionize photovoltaic technology. Hunter McDaniel, Los

  5. NREL: Transportation Research - Transportation News

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Transportation News The following news stories highlight transportation research at NREL. November 4, 2016 NREL Technologies Honored at R&D 100 Awards Ceremony Research teams honored for advances in residential buildings, energy storage testing and power inverters November 1, 2016 NREL Issued Patent for Award-Winning Isothermal Battery Calorimeters The National Renewable Energy Laboratory (NREL) was recently issued a patent for its R&D 100 Award-winning Isothermal Battery Calorimeters

  6. NREL: Transportation Research - Publications

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Publications NREL researchers document their findings in technical reports, conference papers, journal articles, and fact sheets. Visit the following online resources to find publications about sustainable transportation research, development, and deployment. Capabilities Overviews These recent publications highlight some of our capabilities, facilities, and projects: Image of fact sheet cover. Sustainable Transportation This overview fact sheet describes NREL's sustainable transportation

  7. NREL: Transportation Research - News

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    News NREL provides a number of transportation and hydrogen news sources. Transportation News Find news stories that highlight NREL's transportation research, development, and deployment (RD&D) activities, including work on vehicles and fuels. Hydrogen and Fuel Cells News Find news stories that highlight NREL's hydrogen RD&D activities, including work on fuel cell electric vehicle technologies. Transportation and Hydrogen Newsletter Stay up to date on NREL's RD&D of transportation and

  8. Research Challenge 2: Quantum Dots and Phosphors

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    2: Quantum Dots and Phosphors - Sandia Energy Energy Search Icon Sandia Home Locations Contact Us Employee Locator Energy & Climate Secure & Sustainable Energy Future Stationary ...

  9. Los Alamos researchers unravel the mystery of quantum dot blinking

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Researchers unravel the mystery of quantum dot blinking Los Alamos researchers unravel the mystery of quantum dot blinking Most exciting is that the Los Alamos researchers have shown that blinking can be controlled and even completely suppressed electrochemically. November 9, 2011 Los Alamos National Laboratory sits on top of a once-remote mesa in northern New Mexico with the Jemez mountains as a backdrop to research and innovation covering multi-disciplines from bioscience, sustainable energy

  10. Nontoxic quantum dot research improves solar cells

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Nancy Ambrosiano Communications Office (505) 667-0471 Email "For the first time, we have certified the performance of a quantum dot sensitized solar cell at greater than 5 percent, ...

  11. Cornell dots research collaboration leads to $10M cancer center...

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    dots research collaboration leads to 10M cancer center September 24th, 2015 Provided... are designed to either adhere to and light up cancer cells or quickly leave the body. ...

  12. NREL: Transportation Research - Projects

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Projects Illustration of aerodynamic light-, medium, and heavy-duty vehicles. NREL research helps optimize the energy efficiency of a wide range of vehicle technologies and applications. NREL's innovative transportation research, development, and deployment projects accelerate widespread adoption of high-performance, low-emission, energy-efficient passenger and freight vehicles, as well as alternative fuels and related infrastructure. The following NREL transportation projects are propelling

  13. NREL: Transportation Research - Webmaster

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Webmaster Please enter your name and email address in the boxes provided, then type your message below. When you are finished, click "Send Message." NOTE: If you enter your e-mail address incorrectly, we will be unable to reply. Your name: Your email address: Your message: Send Message Printable Version Transportation Research Home Capabilities Projects

  14. Quantum transport through the system of parallel quantum dots with Majorana bound states

    SciTech Connect

    Wang, Ning; Li, Yuxian; Lv, Shuhui

    2014-02-28

    We study the tunneling transport properties through a system of parallel quantum dots which are coupled to Majorana bound states (MBSs). The conductance and spectral function are computed using the retarded Green's function method based on the equation of motion. The conductance of the system is 2e{sup 2}/h at zero Fermi energy and is robust against the coupling between the MBSs and the quantum dots. The dependence of the Fermi energy on the spectral function is different for the first dot (dot1) than for the second dot (dot2) with fixed dot2-MBSs coupling. The influence of the Majorana bound states on the spectral function was studied for the series and parallel configurations of the system. It was found that when the configuration is in series, the Majorana bound states play an important role, resulting in a spectral function with three peaks. However, the spectral function shows two peaks when the system is in a parallel configuration. The zero Fermi energy spectral function is always 1/2 not only in series but also in the parallel configuration and robust against the coupling between the MBSs and the quantum dots. The phase diagram of the Fermi energy versus the quantum dot energy levels was also investigated.

  15. NREL: Transportation Research - Transportation and Hydrogen Newsletter

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Transportation and Hydrogen Newsletter The Transportation and Hydrogen Newsletter is a monthly electronic newsletter that provides information on NREL's research, development, and deployment of transportation and hydrogen technologies. Photo of a stack of newspapers September 2016 Issue Fuels Performance Read the latest issue of the newsletter. Subscribe: To receive new issues by email, subscribe to the newsletter. Archives: For past issues, read the newsletter archives. Printable Version

  16. NREL: Transportation Research - Sustainable Transportation Basics

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Transportation Basics Compare Vehicle Technologies 3-D illustration of electric car diagramming energy storage, power electronics, and climate control components. The following links to the U.S. Department of Energy's Alternative Fuels Data Center (AFDC) provide an introduction to sustainable transportation. NREL research supports development of electric, hybrid, hydrogen fuel cell, biofuel, natural gas, and propane vehicle technologies. Learn more about vehicles, fuels, and transportation

  17. the-transportation-research-board

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    January 22-26, 2012 The Transportation Research Board (TRB) 91st Annual Meeting will be held in Washington, D.C. at the Washington Marriott Wardman Park, Omni Shoreham, and Washington Hilton hotels. The information-packed program will attract more than 11,000 transportation professionals from around the world to Washington, D.C., January 22-26, 2012. The Transportation Research and Analysis Computing Center (TRACC) team will showcase current projects at the upcoming Transportation Research Board

  18. Transport through an impurity tunnel coupled to a Si/SiGe quantum dot

    SciTech Connect

    Foote, Ryan H. Ward, Daniel R.; Thorgrimsson, Brandur; Savage, D. E.; Friesen, Mark; Coppersmith, S. N.; Eriksson, M. A.; Prance, J. R.; Gamble, John King; Nielsen, Erik; Saraiva, A. L.

    2015-09-07

    Achieving controllable coupling of dopants in silicon is crucial for operating donor-based qubit devices, but it is difficult because of the small size of donor-bound electron wavefunctions. Here, we report the characterization of a quantum dot coupled to a localized electronic state and present evidence of controllable coupling between the quantum dot and the localized state. A set of measurements of transport through the device enable the determination that the most likely location of the localized state is consistent with a location in the quantum well near the edge of the quantum dot. Our results are consistent with a gate-voltage controllable tunnel coupling, which is an important building block for hybrid donor and gate-defined quantum dot devices.

  19. Exciton dissociation and interdot transport in CdSe quantum-dot molecules

    SciTech Connect

    Franceschetti, Alberto; Zunger, Alex

    2001-04-15

    One of the most important parameters that determine the transport properties of a quantum dot array is the exciton dissociation energy, i.e., the energy {Delta}E required to dissociate an exciton into an electron and a hole localized in different dots. We show that a pseudopotential calculation for a dot molecule, coupled with a basic configuration interaction calculation of the exciton energy levels, provides directly the exciton dissociation energy, including the effects of wave function overlap, screened Coulomb attraction between the electron and the hole in different dots, and polarization effects. We find that {Delta}E decreases as the interdot distance decreases and as the dielectric constant of the medium increases.

  20. NREL: Transportation Research - Capabilities

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    A Vision for Sustainable Transportation Line graph illustrating three pathways (biofuel, hydrogen, and electric vehicle) to reduce energy use and greenhouse gas emissions. Electric ...

  1. Expansion of DOE-DOT Tight Oil Research Work

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Engineering and Application Center for Hydrogen Energy Research Programs ARPA-E Basic ... oils as they relate to potential combustion events in the rail transport environment. ...

  2. NREL: Transportation Research Home Page

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Transportation Research Silver Toyota Prius being driven in front of NREL entrance sign. NREL helps industry partners develop the next generation of energy efficient, high performance vehicles and fuels. Thermal image of two men standing in front of tractor trailer cab. NREL conducts research on the full range of vehicle types, from light-duty passenger cars to heavy-duty freight trucks. Female researcher holding coin cell battery. NREL's transportation research spans from the materials to the

  3. Transport Research Laboratory | Open Energy Information

    OpenEI (Open Energy Information) [EERE & EIA]

    Research Laboratory Jump to: navigation, search Tool Summary LAUNCH TOOL Name: Transport Research Laboratory AgencyCompany Organization: Transport Research Laboratory Focus Area:...

  4. NREL: Transportation Research - Facilities

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Facilities NREL conducts vehicles and fuels research in laboratories and test sites on its 327-acre main campus in Golden, Colorado, and at specialized facilities within the region. Industry, government, and university partners benefit from access to NREL equipment and facilities tailored to analyze a broad spectrum of energy-efficient vehicle and fuel technologies and innovations. NREL engineers and researchers work closely with a wide variety of partners to research and develop advanced

  5. The impact of disorder on charge transport in three dimensional quantum dot resonant tunneling structures

    SciTech Connect

    Puthen-Veettil, B. Patterson, R.; Knig, D.; Conibeer, G.; Green, M. A.

    2014-10-28

    Efficient iso-entropic energy filtering of electronic waves can be realized through nanostructures with three dimensional confinement, such as quantum dot resonant tunneling structures. Large-area deployment of such structures is useful for energy selective contacts but such configuration is susceptible to structural disorders. In this work, the transport properties of quantum-dot-based wide-area resonant tunneling structures, subject to realistic disorder mechanisms, are studied. Positional variations of the quantum dots are shown to reduce the resonant transmission peaks while size variations in the device are shown to reduce as well as broaden the peaks. Increased quantum dot size distribution also results in a peak shift to lower energy which is attributed to large dots dominating transmission. A decrease in barrier thickness reduces the relative peak height while the overall transmission increases dramatically due to lower series resistance. While any shift away from ideality can be intuitively expected to reduce the resonance peak, quantification allows better understanding of the tolerances required for fabricating structures based on resonant tunneling phenomena/.

  6. NREL: Transportation Research - Success Stories

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Success Stories NREL understands real-world factors impacting industry and consumer adoption of sustainable transportation solutions, resulting in an impressive record of breaking down barriers to accelerate development and deployment of new transportation technologies. The success stories below provide a snapshot of how NREL research, development, and deployment activities translate into more energy-efficient vehicles and cleaner burning fuels, providing viable options to meet the needs of

  7. NREL: Transportation Research - Energy Storage

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Energy Storage Transportation Research Cutaway image of an automobile showing the location of energy storage components (battery and inverter), as well as electric motor, power electronics controller, and heat exchangers. Blowout shows the image of an individual battery pack. NREL research is pointing the way toward affordable, high-performing, long-lasting batteries for the next generation of electric-drive vehicles. Researcher holding cables and standing in front of an open equipment chamber.

  8. Cornell dots research collaboration leads to $10M cancer center > EMC2 News

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    > The Energy Materials Center at Cornell dots research collaboration leads to $10M cancer center September 24th, 2015 › Provided/Wiesner Lab A rendering of the molecular structure of a Cornell dot, which is smaller than 10 nanometers. Provided/Wiesner Lab A transmission electron microscope image of Cornell dots. C dots, which are injected into patients, are designed to either adhere to and light up cancer cells or quickly leave the body. Cornell University, in partnership with Memorial

  9. Charge transport and memristive properties of graphene quantum dots embedded in poly(3-hexylthiophene) matrix

    SciTech Connect

    Cosmin Obreja, Alexandru; Cristea, Dana; Radoi, Antonio; Gavrila, Raluca; Comanescu, Florin; Kusko, Cristian; Mihalache, Iuliana

    2014-08-25

    We show that graphene quantum dots (GQD) embedded in a semiconducting poly(3-hexylthiophene) polymeric matrix act as charge trapping nanomaterials. In plane current-voltage (I-V) measurements of thin films realized from this nanocomposite deposited on gold interdigitated electrodes revealed that the GQD enhanced dramatically the hole transport. I-V characteristics exhibited a strong nonlinear behavior and a pinched hysteresis loop, a signature of a memristive response. The transport properties of this nanocomposite were explained in terms of a trap controlled space charge limited current mechanism.

  10. Elastic tunneling charge transport mechanisms in silicon quantum dots /SiO{sub 2} thin films and superlattices

    SciTech Connect

    Illera, S. Prades, J. D.; Cirera, A.

    2015-05-07

    The role of different charge transport mechanisms in Si/SiO{sub 2} structures has been studied. A theoretical model based on the Transfer Hamiltonian Formalism has been developed to explain experimental current trends in terms of three different elastic tunneling processes: (1) trap assisted tunneling; (2) transport through an intermediate quantum dot; and (3) direct tunneling between leads. In general, at low fields carrier transport is dominated by the quantum dots whereas, for moderate and high fields, transport through deep traps inherent to the SiO{sub 2} is the most relevant process. Besides, current trends in Si/SiO{sub 2} superlattice structure have been properly reproduced.

  11. Resonant electronic transport through a triple quantum-dot with Λ-type level structure under dual radiation fields

    SciTech Connect

    Guan, Chun; Xing, Yunhui; Zhang, Chao; Ma, Zhongshui

    2014-08-14

    Due to quantum interference, light can transmit through dense atomic media, a phenomenon known as electromagnetically induced transparency (EIT). We propose that EIT is not limited to light transmission and there is an electronic analog where resonant transparency in charge transport in an opaque structure can be induced by electromagnetic radiation. A triple-quantum-dots system with Λ-type level structure is generally opaque due to the level in the center dot being significantly higher and therefore hopping from the left dot to the center dot is almost forbidden. We demonstrate that an electromagnetically induced electron transparency (EIET) in charge of transport can indeed occur in the Λ-type system. The direct evidence of EIET is that an electron can travel from the left dot to the right dot, while the center dot apparently becomes invisible. We analyze EIET and the related shot noise in both the zero and strong Coulomb blockade regimes. It is found that the EIET (position, height, and symmetry) can be tuned by several controllable parameters of the radiation fields, such as the Rabi frequencies and detuning frequencies. The result offers a transparency/opaque tuning technique in charge transport using interfering radiation fields.

  12. Low-temperature transport in ac-driven quantum dots in the Kondo regime

    SciTech Connect

    Lopez, Rosa; Aguado, Ramon; Platero, Gloria; Tejedor, Carlos

    2001-08-15

    We present a fully nonequilibrium calculation of the low-temperature transport properties of a quantum dot in the Kondo regime when an ac potential is applied to the gate. We solve a time-dependent Anderson model with finite on-site Coulomb interaction. The interaction self-energy is calculated up to second order in perturbation theory in the on-site interaction, in the context of the Keldysh nonequilibrium technique, and the effect of the ac voltage is taken into account exactly for all ranges of ac frequencies and ac intensities. The obtained linear conductance and time-averaged density of states of the quantum dot evolve in a nontrivial way as a function of the ac frequency and ac intensity of the harmonic modulation.

  13. NREL: Transportation Research - Transportation Deployment Support

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Transportation Deployment Support Photo of a car parked in front of a monument. A plug-in electric vehicle charges near the Thomas Jefferson Memorial in Washington, D.C. Photo from Julie Sutor, NREL NREL's transportation deployment team works with vehicle fleets, fuel providers, and other transportation stakeholders to help deploy alternative and renewable fuels, advanced vehicles, fuel economy improvements, and fleet-level efficiencies that reduce emissions and petroleum dependence. In

  14. NREL: Transportation Research - Transportation and Hydrogen Newsletter...

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    This is the May 2015 issue of the Transportation and Hydrogen Newsletter. May 28, 2015 Photo of a car refueling at a hydrogen dispensing station. DOE's H2FIRST project focuses on ...

  15. A commentary on the 1995 DOT/NRC amendments to the U.S. nuclear transportation regulations

    SciTech Connect

    Grella, A.

    1996-07-01

    This article discusses the major revisions (1995 DOT/NRC ammendments) to the US Nuclear Transportation regulations and their probable impacts on transportation. Areas covered include the following: the LSA and SCO definitions and packaging; radiation protection programs; mandatory use of SI units; changes an additions to the table of A1/A2 radionuclide values; and additional type B package hypothetical accident parameters.

  16. NREL: Transportation Research - Transportation and Hydrogen Newsletter...

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    ... and university researchers to support improved motor designs. Although the research focused on electric machines for electric-drive vehicle applications, the results are applicable ...

  17. NREL: Transportation Research - Transportation and Hydrogen Newsletter:

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Fuels Performance Fuels Performance This is the September 2016 issue of the Transportation and Hydrogen Newsletter. September 26, 2016 A photo of a worker using a small crane to lift a cylindrical tank. Compressed natural gas (CNG) tanks, such as those shown above, should be retired from service following a safety protocol and manufacturers' instructions, according to NREL's CNG tank decommissioning video. Video Promotes Safe CNG Tank Decommissioning Practices A video on CNG fuel tank

  18. NREL: Transportation Research - Transportation and Hydrogen Newsletter:

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Energy Storage Energy Storage This is the November 2015 issue of the Transportation and Hydrogen Newsletter. November 6, 2015 Photo of a light blue car with a pump nozzle in front of a fuel dispenser. Hydrogen is pumped into a fuel cell electric vehicle at NREL's new station. Image by Dennis Schroeder/NREL 34598 New H2 Station Launched In fuel cell electric vehicles, energy is stored in hydrogen gas and then converted to electricity in a fuel cell. In October, NREL dedicated a 700-bar

  19. NREL: Transportation Research - Transportation and Hydrogen Newsletter:

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Market Impact Hydrogen Fuel Cells This is the July 2016 issue of the Transportation and Hydrogen Newsletter. July 28, 2016 A photo of a public hydrogen fuel cell bus parked in a parking lot. Fuel cell electric buses (FCEBs), such as this one operating in Oakland, California, are providing data to compare FCEB performance with that of buses using conventional technology. Photo by Leslie Eudy, NREL NREL Helps Pave Way for H2 Technologies As deployment of hydrogen fueling stations increases to

  20. Center for Transportation Research | Argonne National Laboratory

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Center for Transportation Research Argonne's Center for Transportation Research (CTR) provides innovative solutions to challenges involving fuel efficiency, emissions, durability, safety, design and operating efficiency, petroleum dependence, interoperability, compatibility and codes/standards compliance and harmonization. The CTR is home to a well-balanced transportation research program staffed by world-class researchers and engineers, who are well known in the technical community and within

  1. Kondo-type transport through a quantum dot under magnetic fields

    SciTech Connect

    Dong, Bing; Lei, X. L.

    2001-06-15

    In this paper, we investigate the Kondo correlation effects on linear and nonlinear transport in a quantum dot connected to reservoirs under finite magnetic fields, using the slave-boson mean field approach suggested by Kotliar and Ruckenstein [Phys. Rev. Lett. >57, 1362 (1986)]. A brief comparison between the present formulation and other slave-boson formulation is presented to justify this approach. The numerical results show that the linear conductance near electron-hole symmetry is suppressed by the application of the magnetic fields, but an anomalous enhancement is predicted in the nonsymmetry regime. The effect of external magnetic fields on the nonlinear differential conductances is discussed for the Kondo system. A significant reduction of the peak splitting is observed due to the strong Kondo correlation, which agrees well with experimental data.

  2. Transportation Research Board 94th Annual Meeting

    Energy.gov [DOE]

    The Transportation Research Board 94th Annual Meeting will be held January 11–15, 2015, in Washington, D.C. at the Walter E. Washington Convention Center. The event covers the entire transportation...

  3. 1995 revisions to the DOT/NRC transport regulations and their impact on nuclear power plants

    SciTech Connect

    Grella, A.W.

    1996-10-01

    On September 28, 1995, the U.S. Department of Transportation (DOT) and the U.S. Nuclear Regulatory Commission (NRC) published major amendments to the nuclear transportation regulations of the US. The amendments culminated an approximate 8-year effort of the two agencies to conform US regulations (to the extent practicable) to the international transport standards of the International Atomic Energy Agency (IAEA) Safety Series N. 6, {open_quotes}Regulations For The Safe Transport of Radioactive Material{close_quotes}, 1985 Edition (Revised 1990). This paper identifies the major revisions to the regulations which have taken place and discusses not only their probable future impacts but also identifies certain issues and early impacts which have been emerging since publication of the final rules late in 1995. The discussion is summarized with respect to these impacts and issues on transportation of radioactive material by the nuclear power industry. Many of the revisions which are more minor in nature are also identified. The generic effective date for mandatory compliance with the revised regulations was April 1, 1996, however two of the major revisions of interest to the utilities have later effective dates for mandatory compliance. The use of the so-called {open_quotes}NRC-Certified Type A LSA Packages{close_quotes} are authorized until April 1, 1999 and mandatory compliance with the new radiation protection program requirements of 49 CFR 172 Subpart I is not until October 1, 1997. This paper is based to a large extent on the EPRI report bearing the same title as this paper, which is currently in draft.

  4. NREL: Transportation Research - Subscribe to the Transportation and

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Hydrogen Newsletter Subscribe to the Transportation and Hydrogen Newsletter To subscribe to or unsubscribe from the Transportation and Hydrogen Newsletter, complete one of the forms below. Subscribe To subscribe to the newsletter, submit your email address. Email: Submit Unsubscribe To unsubscribe from the newsletter, submit your email address. Email: Submit Printable Version Transportation Research Home Capabilities Projects Success Stories Facilities Working with Us Publications Data &

  5. Comparative study of donor-induced quantum dots in Si nano-channels by single-electron transport characterization and Kelvin probe force microscopy

    SciTech Connect

    Tyszka, K.; Moraru, D.; Samanta, A.; Mizuno, T.; Tabe, M.; Jabłoński, R.

    2015-06-28

    We comparatively study donor-induced quantum dots in Si nanoscale-channel transistors for a wide range of doping concentration by analysis of single-electron tunneling transport and surface potential measured by Kelvin probe force microscopy (KPFM). By correlating KPFM observations of donor-induced potential landscapes with simulations based on Thomas-Fermi approximation, it is demonstrated that single-electron tunneling transport at lowest gate voltages (for smallest coverage of screening electrons) is governed most frequently by only one dominant quantum dot, regardless of doping concentration. Doping concentration, however, primarily affects the internal structure of the quantum dot. At low concentrations, individual donors form most of the quantum dots, i.e., “donor-atom” quantum dots. In contrast, at high concentrations above metal-insulator transition, closely placed donors instead of individual donors form more complex quantum dots, i.e., “donor-cluster” quantum dots. The potential depth of these “donor-cluster” quantum dots is significantly reduced by increasing gate voltage (increasing coverage of screening electrons), leading to the occurrence of multiple competing quantum dots.

  6. NREL: Transportation Research - A Vision for Sustainable Transportation

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    A Vision for Sustainable Transportation NREL research, development, and deployment accelerates the process of bringing sustainable transportation technologies to market. Line graph illustrating three pathways to reduce transportation energy use and greenhouse gas (GHG) emissions, with "energy consumption of vehicles" along the y-axis (ranging from 0 to 2.0 kWh/km) and "carbon intensity of energy source" along the x-axis (ranging from 450 to 0 g CO2/kWh). A solid bottom line

  7. Transportation Secure Data Center: Real-World Data for Value Pricing and Tolling Research (Fact Sheet)

    SciTech Connect

    Not Available

    2013-01-01

    The National Renewable Energy Laboratory (NREL) and the U.S. Department of Transportation (DOT) have launched the free, web-based Transportation Secure Data Center (TSDC). The TSDC (www.nrel.gov/tsdc) preserves respondent anonymity while making vital transportation data available to a broad group of users through secure, online access. The TSDC database provides free-of-charge web-based access to valuable transportation data that can be used for: Location and time-of-day variable tolling research, Mileage-based fee analysis, Travel demand modeling and transit planning, Congestion mitigation research, and Validating transportation data from other sources. The TSDC's two levels of access make composite data available with simple online registration, and allow researchers to use detailed spatial data after completing a straight forward application process.

  8. New Transportation Technology | GE Global Research

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Transportation We're working with railroads and heavy industries to create hybrid systems, batteries and first-in-class transportation solutions. Home > Innovation > Transportation Silicon Carbide Applications: Small Device, Broad Impact in Power Electronics It's not every day that the engineers at GE Global Research get their hands on a material that's literally revolutionizing an... Read More » Data Science Makes Trains More Efficient In this Special Report, GE's Creator-in-Residence,

  9. NREL: Transportation Research - Energy Storage

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Research Cutaway image of an automobile showing the location of energy storage components (battery and inverter), as well as electric motor, power electronics controller, and heat ...

  10. NREL: Transportation Research - Fuels Performance

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Fuels Performance Photo of a man working with laboratory equipment. NREL fuel performance chemists evaluate a broad range of performance criteria, including storage stability. Photo by Dennis Schroeder, NREL NREL's applied fuels performance research takes a whole-vehicle-systems approach, examining not just co-optimization of low-carbon fuels and internal combustion engines, but also fuel production, infrastructure, handling, combustion, and emissions. Putting more energy-efficient vehicles on

  11. The role of transport processes of nonequilibrium charge carriers in radiative properties of arrays of InAs/GaAs quantum dots

    SciTech Connect

    Shkolnik, A. S. Savelyev, A. V.; Karachinsky, L. Ya.; Gordeev, N. Yu.; Seisyan, R. P.; Zegrya, G. G.; Pellegrini, S.; Buller, G. S.; Evtikhiev, V. P.

    2008-03-15

    The results of time-resolved photoluminescence studies of heterostructures containing monolayer arrays of InAs/GaAs quantum dots are presented. A two-component time dependence of intensity of photoluminescence from the ground state of quantum dots, with characteristic times of the slow component up to hundreds of nanoseconds and those of rapid one several nanoseconds, is studied. It is shown that the slow component is determined by the transport of nonequilibrium charge carriers between the quantum dots. At low temperatures, the time of the slow component is determined by tunneling, and at high temperatures by thermal escape of nonequilibrium charge carriers. The ratio of the contributions of tunneling and thermal escape is determined by the degree of isolation of quantum dots. A theoretical model is constructed that describes the effect of the dynamics of carrier transport on the emergence and decay of the slow component of photoluminescence.

  12. Promising future of quantum dots explored in conference

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Promising future of quantum dots explored Promising future of quantum dots explored in conference Researchers are gathering to reflect on two decades of quantum dot research at a ...

  13. NREL: Transportation Research - Working with Us

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Working with Us Partnerships Drive Transportation Solutions Photo of two men standing in front of a large solar panel and an electric vehicle. NREL offers industry, academia, and government agencies opportunities to work with us and leverage our research expertise and capabilities. There are several ways for your organization to get involved with us: Partner with NREL through a Cooperative Research and Development Agreement or a Work-for-Others Agreement. License NREL-developed technologies. The

  14. Cost-effectiveness analysis of TxDOT LPG fleet conversion. Volume 1. Interim research report

    SciTech Connect

    Euritt, M.A.; Taylor, D.B.; Mahmassani, H.

    1992-10-01

    Increased emphasis on energy efficiency and air quality has resulted in a number of state and federal initiatives examining the use of alternative fuels for motor vehicles. Texas' program for alternate fuels includes liquefied petroleum gas (LPG). Based on an analysis of 30-year life-cycle costs, development of a propane vehicle program for the Texas Department of Transportation (TxDOT) would cost about $24.3 million (in 1991 dollars). These costs include savings from lower-priced LPG and differentials between propane and gasoline/diesel in infrastructure costs for a fueling station, vehicle costs, and operating costs. The 30-year life-cycle costs translate into an average annual vehicle cost increase of $308, or about 2.5 cents more per vehicle mile of travel. Sensitivity analyses are performed on the discount rate, price of propane, maintenance savings, vehicle utilization, diesel vehicles, extended vehicle life, original equipment manufacturer (OEM) vehicles, and operating and infrastructure costs. The best results are obtained when not converting diesel vehicles, converting only large fleets, and extending the period the vehicle is kept in service. Combining these factors yields results that are most cost-effective for TxDOT. This is volume one of two volumes.

  15. Cost-effectiveness analysis of TxDOT LPG fleet conversion. Volume 2. Interim research report

    SciTech Connect

    Euritt, M.A.; Taylor, D.B.; Mahmassani, H.

    1992-11-01

    Increased emphasis on energy efficiency and air quality has resulted in a number of state and federal initiatives examining the use of alternative fuels for motor vehicles. Texas' program for alternate fuels includes liquefied petroleum gas (LPG), commonly called propane. Based on an analysis of 30-year life-cycle costs, development of a propane vehicle program for the Texas Department of Transportation (TxDOT) would cost about $24.3 million (in 1991 dollars). These costs include savings from lower-priced propane and differentials between propane and gasoline/diesel in infrastructure costs, vehicle costs, and operating costs. The 30-year life-cycle costs translate into an average annual vehicle cost increase of $308, or about 2.5 cents more per vehicle mile of travel. Based on the cost-effectiveness analysis and assumptions, there are currently no TxDOT locations that can be converted to propane without additional financial outlays. This is volume two of two volumes.

  16. NREL: Transportation Research - Data, Models, and Tools

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Data, Models, and Tools NREL offers models, tools, data, and other resources for vehicle fleet managers, researchers, developers, and others interested in the viability, analysis, and development of advanced transportation technologies and systems. ADOPT: Automotive Deployment Options Projection Tool Modeling tool that predicts consumer demand for different vehicle types based on income distribution and other demographic attributes in a given region. ADOPT's market predictions have been

  17. Center for Transportation Research: The Road to Mobility Innovation Starts

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Here | Argonne National Laboratory Center for Transportation Research: The Road to Mobility Innovation Starts Here Not since the invention of the automobile has the future of transportation held such potential. The Center for Transportation Research at Argonne National Laboratory is blazing the way forward, leading on advanced transportation research and development and contributing expertise, tools and facilities for innovation. PDF icon center_for_transportation_research

  18. NREL Researchers Demonstrate External Quantum Efficiency Surpassing 100% in a Quantum Dot Solar Cell (Fact Sheet)

    SciTech Connect

    Not Available

    2011-12-01

    A new device that produces and collects multiple electrons per photon could yield inexpensive, high-efficiency photovoltaics. A new device developed through research at the National Renewable Energy Laboratory (NREL) reduces conventional losses in photovoltaic (PV) solar cells, potentially increasing the power conversion efficiency-but not the cost-of the solar cells. Solar cells convert optical energy from the sun into usable electricity; however, almost 50% of the incident energy is lost as heat with present-day technologies. High-efficiency, multi-junction cells reduce this heat loss, but their cost is significantly higher. NREL's new device uses excess energy in solar photons to create extra charges rather than heat. This was achieved using 5-nanometer-diameter quantum dots of lead selenide (PbSe) tightly packed into a film. The researchers chemically treated the film, and then fabricated a device that yielded an external quantum efficiency (number of electrons produced per incident photon) exceeding 100%, a value beyond that of all current solar cells for any incident photon. Quantum dots are known to efficiently generate multiple excitons (a bound electron-hole pair) per absorbed high-energy photon, and this device definitively demonstrates the collection of multiple electrons per photon in a PV cell. The internal quantum efficiency corrects for photons that are not absorbed in the photoactive layer and shows that the PbSe film generates 30% to 40% more electrons in the high-energy spectral region than is possible with a conventional solar cell. While the unoptimized overall power conversion efficiency is still low (less than 5%), the results have important implications for PV because such high quantum efficiency can lead to more electrical current produced than possible using present technologies. Furthermore, this fabrication is also amenable to inexpensive, high-throughput roll-to-roll manufacturing.

  19. UC Berkeley-Transportation Sustainability Research Center | Open...

    OpenEI (Open Energy Information) [EERE & EIA]

    Sustainability Research Center Jump to: navigation, search Name: UC Berkeley-Transportation Sustainability Research Center Address: 2614 Dwight Way Place: Berkeley, California Zip:...

  20. NREL: Transportation Research - NPR Features Transportation and Hydrogen

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Systems Center Director Chris Gearhart NPR Features Transportation and Hydrogen Systems Center Director Chris Gearhart September 30, 2016 National Public Radio (NPR) recently featured the National Renewable Energy Laboratory's (NREL's) Chris Gearhart, director of NREL's Transportation and Hydrogen Systems Center, in an interview on the affordability of low-emission vehicles. "I come to work every day because I think that getting greenhouse gas emissions out of the transportation sector

  1. Transportation Research and Analysis Computing Center Fact Sheet | Argonne

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Transportation Equipment (2010 MECS) Transportation Equipment (2010 MECS) Manufacturing Energy and Carbon Footprint for Transportation Equipment Sector (NAICS 336) Energy use data source: 2010 EIA MECS (with adjustments) Footprint Last Revised: February 2014 View footprints for other sectors here. Manufacturing Energy and Carbon Footprint Transportation Equipment (125.57 KB) More Documents & Publications MECS 2006 - Transportation Equipment National Laboratory

    Transportation Research

  2. Transport properties and Kondo correlations in nanostructures: Time-dependent DMRG method applied to quantum dots coupled to Wilson chains

    SciTech Connect

    Dias Da Silva, Luis G; Heidrich-Meisner, Fabian; Feiguin, Adrian E; Busser, C. A.; Martins, G. B.; Anda, E. V.; Dagotto, Elbio R

    2008-01-01

    We apply the adaptive time-dependent density-matrix renormalization-group method tDMRG to the study of transport properties of quantum-dot systems connected to metallic leads. Finite-size effects make the usual tDMRG description of the Kondo regime a numerically demanding task. We show that such effects can be attenuated by describing the leads by Wilson chains, in which the hopping matrix elements decay exponentially away from the impurity tn n/2. For a given system size and in the linear-response regime, results for 1 show several improvements over the undamped =1 case: perfect conductance is obtained deeper in the strongly interacting regime and current plateaus remain well defined for longer time scales. Similar improvements were obtained in the finite-bias regime up to bias voltages of the order of the Kondo temperature. These results show that with the proposed modification, the tDMRG characterization of Kondo correlations in the transport properties can be substantially improved, while it turns out to be sufficient to work with much smaller system sizes. We discuss the numerical cost of this approach with respect to the necessary system sizes and the entanglement growth during the time evolution.

  3. Superconducting transport in single and parallel double InAs quantum dot Josephson junctions with Nb-based superconducting electrodes

    SciTech Connect

    Baba, Shoji Sailer, Juergen; Deacon, Russell S.; Oiwa, Akira; Shibata, Kenji; Hirakawa, Kazuhiko; Tarucha, Seigo

    2015-11-30

    We report conductance and supercurrent measurements for InAs single and parallel double quantum dot Josephson junctions contacted with Nb or NbTiN superconducting electrodes. Large superconducting gap energy, high critical field, and large switching current are observed, all reflecting the features of Nb-based electrodes. For the parallel double dots, we observe an enhanced supercurrent when both dots are on resonance, which may reflect split Cooper pair tunneling.

  4. NREL: Transportation Research - Successful Transportation Lab-Industry

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Collaborations Spotlighted at Summit Successful Transportation Lab-Industry Collaborations Spotlighted at Summit Five men stand outside in front of passenger car and white modular building. On display at the National Lab Impact Summit, a Toyota Mirai fuel cell electric vehicle from NREL paired with a 3D-printed building from ORNL can work together to produce and store renewable energy. Image Dennis Schroeder, NREL. May 18, 2016 On May 4, NREL hosted leaders from the business, government, and

  5. NREL: Transportation Research - Vehicle Thermal Management

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    transported across the United States each year. Idling these vehicles to heat and cool cabsleeper spaces improves driver comfort and safety, but consumes large quantities of...

  6. Defense, NASA and Transportation Research Added to Searchable Summaries |

    Office of Scientific and Technical Information (OSTI)

    OSTI, US Dept of Energy Office of Scientific and Technical Information Defense, NASA and Transportation Research Added to Searchable Summaries Back to the OSTI News Listing for 2009 Now you can find research project summaries from the Department of Defense, NASA, and the Transportation Research Board at Federal R&D Project Summaries. From a New York City Park and Ride Study to Defense Research Sciences Budget Activity to Transgenic Plant Biomonitors of Space Flight Exposure, the portal

  7. NREL: Transportation Research - News Release Archives

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    2 December 28, 2012 Clean Cities YouTube Channel Offers Videos on Alternative Fuels and Advanced Vehicles The NREL-developed Clean Cities YouTube channel offers informative videos that can help vehicle fleet managers and transportation decision makers reduce petroleum use by gleaning insight from a variety of alternative transportation topics. December 21, 2012 NREL Names New Executive The U.S. Department of Energy's National Renewable Energy Laboratory today named Barbara Goodman as Associate

  8. NREL: Transportation Research - Sustainable Mobility Initiative

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Mobility Initiative Graphic of four concentric circles starting with the traveler and branching out to encompass the vehicle, transport system, and built environment. NREL's Sustainable Mobility Initiative approaches sustainable transportation as a network of travelers, services, and environments-rather than just vehicles and roads-using connectivity and automation to optimize mobility and significantly reduce related energy consumption. This concept of an intelligent, integrated, and dynamic

  9. NREL: Transportation Research - Truck Stop Electrification Testing

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Truck Stop Electrification Testing Photo of series of truck stop electrification pedestals near highway with heavy-duty truck parked in the background. NREL is monitoring the use of truck stop electrification sites across the nation. Photo courtesy of Shorepower Technologies NREL's fleet test and evaluation team is evaluating and documenting the use of 50 truck stop electrification (TSE) sites along the busiest transportation corridors in the United States. Truck drivers typically idle their

  10. NREL: Transportation Research - E-Roadway Animation

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    E-Roadway Animation This animation depicts a potential future transportation scenario in which electric vehicles can be recharged via electrified roadways. E-roadways offer a variety of benefits. They can reduce petroleum consumption (electricity is used instead of gasoline), decrease vehicle operating costs (from about 12 cents per mile to 4 cents per mile), and extend the operational range of electric vehicles. Plus, e-roadway power can come from renewable sources. Text version. Printable

  11. NREL: Transportation Research - NREL's Hydrogen Fueling Infrastructure

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Research: Year in Review NREL's Hydrogen Fueling Infrastructure Research: Year in Review Photo of two fuel cell vehicles parked next to NREL's hydrogen fueling station. FCEVs at NREL's Hydrogen Infrastructure Testing and Research Facility. Photo by Dennis Schroeder, NREL 40155 October 7, 2016 This week the National Renewable Energy Laboratory (NREL) joins others across the United States to celebrate National Hydrogen and Fuel Cell Day on Oct. 8-10.08-a date chosen to represent the atomic

  12. Center for Transportation Research | Argonne National Laboratory

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Advanced Vehicle Technologies Friction, Wear, and Lubrication Technologies Fuel Spray Analysis Multi-Dimensional Modeling Vehicle-Grid Interoperability CTR research occurs in...

  13. New Transportation Technology | GE Global Research

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Read More GE, MIT Build Crowdsourcing Software Platform GE (NYSE: GE), with the Massachusetts Institute of Technology (MIT) and the Defense Advanced Research Agency (DARPA), ...

  14. Research in transportation: the shape of the future

    SciTech Connect

    Chenea, P.F.

    1981-01-01

    The individual mobility now enjoyed due to advancements in the transportation sector is being threatened by higher fuel costs and declining petroleum resources. Transportation research approaches must address these problems. Automotive engineers must redesign existing vehicles to make them smaller, lighter, and so more fuel efficient. Alternatives to the gasoline engine, such as gas turbine and stratified charge engines, must be commercialized.

  15. Vehicle Technologies Office: Data and Analysis for Transportation Research

    Office of Energy Efficiency and Renewable Energy (EERE)

    The U.S. Department of Energy (DOE) — in conjunction with the national laboratories — conducts a wide range of statistical research on energy use, economics, and trends in transportation.

  16. Fuel Cells for Transportation - Research and Development: Program Abstracts

    Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)

    | Department of Energy Research and Development: Program Abstracts Fuel Cells for Transportation - Research and Development: Program Abstracts Remarkable progress has been achieved in the development of proton-exchange-membrane(PEM) fuel cell technology since the U.S. Department of Energy (DOE) initiated a significant developmental program in the early 1990s. This progress has stimulated enormous interest worldwide in developing fuel cell products for transportation as well as for stationary

  17. NREL: Transportation Research - Electric Motor Thermal Management

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Electric Motor Thermal Management A photo of a piece of laboratory testing equipment. NREL research in electric motors is helping to improve the performance and reliability of electric-drive vehicles. Photo by Kevin Bennion, NREL NREL's electric motor thermal management research generates experimental data and simulation processes for the modeling, analysis, design, and construction of new electric motors. Electric motor thermal management involves a multifaceted interaction of motor operating

  18. NREL: Transportation Research - News Release Archives

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    4 November 20, 2014 Innovative Way to Test Batteries Fills a Market Niche Isothermal Battery Calorimeters (IBCs), developed by NREL researchers, are capable of performing the precise thermal measurements needed to make safer, longer-lasting, and more cost-effective batteries for in a variety of applications. November 12, 2014 Webinar November 18: An Overview of the Hydrogen Fueling Infrastructure Research and Station Technology (H2FIRST) Project Led by the National Renewable Energy Laboratory

  19. NREL: Transportation Research - Power Electronics Packaging Reliability

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Packaging Reliability A photo of a piece of power electronics testing equipment. NREL power electronics packaging reliability research investigates the performance and reliability of emerging interconnection, interface, and packaging materials. Findings help improve reliability and durability of emerging technologies. Photo by Dennis Schroeder, NREL Power electronics packaging around a semiconductor switching device determines the electrical, thermal, and mechanical properties of a power

  20. NREL: Transportation Research - Compare Vehicle Technologies

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Compare Vehicle Technologies NREL researchers are simultaneously exploring ways to optimize the legacy internal combustion technology that makes up the vast majority of vehicles on today's roads, while developing the electric, fuel cell, and biofuel technologies needed to transition to a virtually net-zero emissions, non-polluting fleet. See how electric, hybrid, and fuel cell vehicles compare to traditional internal combustion vehicles in the slideshow below. 3-D illustration of electric car

  1. NREL: Transportation Research - News Release Archives

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    0 December 28, 2010 NREL Helps Corporate Fleets Go Green Researchers work with companies to evaluate the latest technology commercially available in the medium and heavy-duty truck markets. December 14, 2010 Hydrogen Bus Lets Lab Visitors Glimpse Future The hydrogen bus uses the same basic technology as a conventional gasoline-powered engine but runs on renewable hydrogen. October 18, 2010 NREL's Hydrogen-Powered Bus Serves as Showcase for Advanced Vehicle Technologies NREL uses its

  2. NREL: Transportation Research - Power Electronics Thermal Management

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Power Electronics Thermal Management A photo of water boiling in liquid cooling lab equipment. Power electronics thermal management research aims to help lower the cost and improve the performance of electric-drive vehicles. Photo by Dennis Schroeder, NREL NREL investigates and develops thermal management strategies for power electronics systems that use wide-bandgap technology, which enables the development of devices that are smaller than those based on other materials, demonstrating

  3. NREL: Transportation Research - Thermal Performance Benchmarking

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Thermal Performance Benchmarking A photo of the internal components of an automotive inverter. NREL thermal performance benchmarking of state-of-the-art power electronics and electric motors helps guide future R&D efforts as well as industry product-development efforts. Photo by Scot Waye, NREL NREL's thermal performance benchmarking research focuses on state-of-the-art technologies used in electric-drive vehicle (EDV) systems. Benchmarks are shared with industry so that systems can be

  4. NREL: Transportation Research - Vehicle Thermal Management Facilities

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Vehicle Thermal Management Facilities Image of a building with two semi truck cabs in front of it. The VTIF is used for thermal testing of every class of on-road vehicle. Photo by Dennis Schroeder, NREL The National Renewable Energy Laboratory (NREL) uses research and testing facilities to develop advanced thermal management technologies for vehicles. Vehicle Testing and Integration Facility The Vehicle Testing and Integration Facility features a test pad to conduct vehicle thermal soak testing

  5. NREL: Transportation Research - Alternative Fuels Characterization

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Alternative Fuels Characterization Find out about other biomass research projects at NREL. NREL alternative fuels projects help overcome technical barriers and expand markets for renewable, biodegradable vehicle fuels. These liquid fuels include higher-level ethanol blends, butanol, biodiesel, renewable diesel, other biomass-derived fuels, and natural gas. By studying the fuel chemistry as well as combustion and emissions impacts of alternative fuels, NREL helps improve engine efficiency, reduce

  6. NREL: Transportation Research - NREL Researcher Jason Lustbader Recognized

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    with SAE Excellence in Oral Presentation Award Researcher Jason Lustbader Recognized with SAE Excellence in Oral Presentation Award Man with dark hair in blue shirt with arms crossed. NREL Senior Research Engineer Jason Lustbader. July 27, 2016 On July 14, 2016, National Renewable Energy Laboratory (NREL) Senior Research Engineer Jason Lustbader was recognized with an SAE Excellence in Oral Presentation Award. The award honors individuals who make outstanding presentations at the SAE World

  7. Promising future of quantum dots explored in conference

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Promising future of quantum dots explored Promising future of quantum dots explored in conference Researchers are gathering to reflect on two decades of quantum dot research at a special topical conference, "20 Years of Quantum Dots at Los Alamos" April 13, 2015 Quantum dot LSC devices under ultraviolet illumination. Quantum dot LSC devices under ultraviolet illumination. Contact Los Alamos National Laboratory Nancy Ambrosiano Communications Office (505) 667-0471 Email "This

  8. DOT specification packages evaluation

    SciTech Connect

    Ratledge, J.E.; Rawl, R.R. )

    1991-01-01

    During the late 1960s and early 1970s, the Department of Transportation (DOT) specification package system was implemented to serve as a useful and equivalent alternative to the Nuclear Regulatory Commission (NRC) and the Bureau of Explosives approval systems for Type B and fissile radioactive material package designs. When a package design was used by a large number of organizations, the package design was added to the DOT regulations as a specification package authorized for use by any shipper. In the mid-1970s, the NRC revised its package design certification system to the one in use today. This paper reports that, while the NRC and DOT transportation regulations have evolved over the years, the DOT specification package designs have remained largely unchanged. Questions have been raised as to whether these designs meet the current and proposed regulations. In order to enable the NRC and DOT to develop a regulatory analysis that will support appropriate action regarding the specification packages, a study is being performed to compile all available design, testing, and analysis information on these packages.

  9. NREL: Transportation Research - Driverless Cars and Fuel Efficiency

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Spotlighted in Scientific American Driverless Cars and Fuel Efficiency Spotlighted in Scientific American January 25, 2016 The potential to slow pollution through deployment of automated vehicles is gaining more and more traction in the news. In a recent Scientific American article, reporter Camille von Kaenel asked NREL's Jeff Gonder for a transportation researcher's thoughts on both the sustainability benefits and uncertainties that will accompany an increase in driverless cars. "The

  10. NREL: Transportation Research - NREL Kicks Off Next Phase of Advanced

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Computer-Aided Battery Engineering NREL Kicks Off Next Phase of Advanced Computer-Aided Battery Engineering March 16, 2016 NREL researcher looks across table at meeting Ahmad Pesaran, Energy Storage Group Manager for NREL's Transportation and Hydrogen Systems Center, led the kickoff meeting for CAEBAT-3 On March 8, NREL hosted the first review meeting of the Advanced Computer-Aided Battery Engineering Consortium, initiating phase three of the collaborative Computer Aided Engineering for

  11. Transportable Heavy Duty Emissions Testing Laboratory and Research Program

    SciTech Connect

    David Lyons

    2008-03-31

    The objective of this program was to quantify the emissions from heavy-duty vehicles operating on alternative fuels or advanced fuel blends, often with novel engine technology or aftertreatment. In the first year of the program West Virginia University (WVU) researchers determined that a transportable chassis dynamometer emissions measurement approach was required so that fleets of trucks and buses did not need to be ferried across the nation to a fixed facility. A Transportable Heavy-Duty Vehicle Emissions Testing Laboratory (Translab) was designed, constructed and verified. This laboratory consisted of a chassis dynamometer semi-trailer and an analytic trailer housing a full scale exhaust dilution tunnel and sampling system which mimicked closely the system described in the Code of Federal Regulations for engine certification. The Translab was first used to quantify emissions from natural gas and methanol fueled transit buses, and a second Translab unit was constructed to satisfy research demand. Subsequent emissions measurement was performed on trucks and buses using ethanol, Fischer-Tropsch fuel, and biodiesel. A medium-duty chassis dynamometer was also designed and constructed to facilitate research on delivery vehicles in the 10,000 to 20,000lb range. The Translab participated in major programs to evaluate low-sulfur diesel in conjunction with passively regenerating exhaust particulate filtration technology, and substantial reductions in particulate matter were recorded. The researchers also participated in programs to evaluate emissions from advanced natural gas engines with closed loop feedback control. These natural gas engines showed substantially reduced levels of oxides of nitrogen. For all of the trucks and buses characterized, the levels of carbon monoxide, oxides of nitrogen, hydrocarbons, carbon dioxide and particulate matter were quantified, and in many cases non-regulated species such as aldehydes were also sampled. Particle size was also

  12. Charge state hysteresis in semiconductor quantum dots

    SciTech Connect

    Yang, C. H.; Rossi, A. Lai, N. S.; Leon, R.; Lim, W. H.; Dzurak, A. S.

    2014-11-03

    Semiconductor quantum dots provide a two-dimensional analogy for real atoms and show promise for the implementation of scalable quantum computers. Here, we investigate the charge configurations in a silicon metal-oxide-semiconductor double quantum dot tunnel coupled to a single reservoir of electrons. By operating the system in the few-electron regime, the stability diagram shows hysteretic tunnelling events that depend on the history of the dots charge occupancy. We present a model which accounts for the observed hysteretic behaviour by extending the established description for transport in double dots coupled to two reservoirs. We demonstrate that this type of device operates like a single-electron memory latch.

  13. Texas Department of Transportation | Open Energy Information

    OpenEI (Open Energy Information) [EERE & EIA]

    Texas Department of Transportation Jump to: navigation, search Logo: Texas Department of Transportation Name: Texas Department of Transportation Abbreviation: TxDOT Place: Austin,...

  14. Chemistry and Transport - Combustion Energy Frontier Research Center

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Chemistry and Transport Chemistry and Transport The overall goal of the flame chemistry working group is to obtain fundamental combustion and emission properties of low and high pressure flames, to validate kinetic and transport models, and to develop accurate and computationally efficient models capable of predicting turbulent combustion of future transportation fuels. Experimental data of laminar and turbulent flame speeds, flame structures, extinction/ignition limits, and soot/NOx emissions

  15. Fuel Cells for Transportation - Research and Development: Program...

    Energy.gov [DOE] (indexed site)

    technology since the U.S. Department of Energy (DOE) initiated a significant ... Fuel Cells For Transportation - 1999 Annual Progress Report Energy Conversion Team Fuel ...

  16. AUTHORIZING THE DOT SPECIFICATION 6M PACKAGING FOR CONTINUED USE AT THE SAVANNAH RIVER SITE

    SciTech Connect

    Watkins, R.; Loftin, B.; Hoang, D.

    2010-03-04

    The U.S. Department of Transportation (DOT) Specification 6M packaging was in extensive use for more than 40 years for in-commerce shipments of Type B quantities of fissile and radioactive material (RAM) across the USA, among the Department of Energy (DOE) laboratories, and between facilities in the DOE production complex. In January 2004, the DOT Research and Special Programs Administration (RSPA) Agency issued a final rule in the Federal Register to ammend requirements in the Hazardous Materials Regulations (HMR) pertaining to the transportation of radioactive materials. The final rule became effective on October 1, 2004. One of those changes discontinued the use of the DOT specification 6M, along with other DOT specification packagings, on October 1, 2008. A main driver for the change was due to the fact that 6M specification packagings were not supported by a Safety Analysis Report for Packagings (SARP) that was compliant with Title 10 of the Code of Federal Regulations (CFR) Part 71 (10 CFR 71). The regulatory rules for the discontinued use have been edited in Title 49 of the CFR Parts 100-185, 2004 edition and thereafter. Prior to October 1, 2008, the use of the 6M within the boundaries of the Savannah River Site (SRS), called an onsite transfer, was governed by an onsite transportation document that referenced 49 CFR Parts 100-185. SRS had to develop an Onsite Safety Assessment (OSA) which was independent of 49 CFR in order to justify the continued use of the DOT Specification 6M for the transfer of radioactive material (RAM) at the SRS after October 1, 2008. This paper will discuss the methodology for and difficulties associated with authorizing the DOT Specification 6M Packaging for continued use at the Savannah River Site.

  17. NREL: Hydrogen and Fuel Cells Research - Successful Transportation

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Lab-Industry Collaborations Spotlighted at Summit Successful Transportation Lab-Industry Collaborations Spotlighted at Summit Five men stand outside in front of passenger car and white modular building. On display at the National Lab Impact Summit, a Toyota Mirai fuel cell electric vehicle from NREL paired with a 3D-printed building from ORNL can work together to produce and store renewable energy. Image Dennis Schroeder, NREL. May 18, 2016 On May 4, NREL hosted leaders from the business,

  18. NREL: Transportation Research - NREL and Fraunhofer ISE to Collaborate on

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Hydrogen and Fuel Cell Research NREL and Fraunhofer ISE to Collaborate on Hydrogen and Fuel Cell Research October 11, 2016 The U.S. Department of Energy's (DOE's) National Renewable Energy Laboratory and the Fraunhofer Institute for Solar Energy Systems (Fraunhofer ISE) in Germany have signed a Memorandum of Understanding (MOU) for close collaboration on hydrogen and fuel cell technologies research. The official launch took place on Monday, Oct. 10, at the "f-cell/World of Energy

  19. NREL: Transportation Research - NREL's Campus EV Charging Stations...

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    NREL's Campus EV Charging Stations are Now More Integrated with the Grid Researcher looks at computer in parking garage standing near electric vehicle charging station. Myungsoo ...

  20. Basic Research Needs for Clean and Efficient Combustion of 21st Century Transportation Fuels

    SciTech Connect

    McIlroy, A.; McRae, G.; Sick, V.; Siebers, D. L.; Westbrook, C. K.; Smith, P. J.; Taatjes, C.; Trouve, A.; Wagner, A. F.; Rohlfing, E.; Manley, D.; Tully, F.; Hilderbrandt, R.; Green, W.; Marceau, D.; O'Neal, J.; Lyday, M.; Cebulski, F.; Garcia, T. R.; Strong, D.

    2006-11-01

    To identify basic research needs and opportunities underlying utilization of evolving transportation fuels, with a focus on new or emerging science challenges that have the potential for significant long-term impact on fuel efficiency and emissions.

  1. Addressing transportation energy and environmental impacts: technical and policy research directions

    SciTech Connect

    Weissenberger, S.; Pasternak, A.; Smith, J.R.; Wallman, H.

    1995-08-01

    The Lawrence Livermore National Laboratory (LLNL) is establishing a local chapter of the University of California Energy Institute (UCEI). In order to most effectively contribute to the Institute, LLNL sponsored a workshop on energy and environmental issues in transportation. This workshop took place in Livermore on August 10 and brought together researchers from throughout the UC systems in order to establish a joint LLNL-UC research program in transportation, with a focus on energy and environmental impacts.

  2. NREL: Transportation Research - NREL Engineer Recognized for Leadership in

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Motor Thermal Management NREL Engineer Recognized for Leadership in Motor Thermal Management Photo of Kevin Bennion with award June 16, 2016 NREL senior engineer and researcher Kevin Bennion received a special recognition award from the U.S. Department of Energy's Vehicle Technologies Office for expertise and leadership in the thermal management of motor designs in electric drive technologies research. The award was presented at a Vehicle Technologies Office ceremony on June 6, 2016, in

  3. NREL: Transportation Research - Power Electronics and Electric Machines

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Facilities and Electric Machines Facilities NREL's power electronics and electric machines thermal management test facilities feature a wide range of equipment and enable world-class experimental and modeling capabilities. NREL researchers excel at testing and measurement in the areas of heat transfer, reliability characterization, and thermal and thermomechanical modeling. The following list describes NREL's innovative testing capabilities and equipment. A photo of four researchers in

  4. NREL: Transportation Research - Renewable Fuels and Lubricants Laboratory

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Renewable Fuels and Lubricants Laboratory Photo of a heavy-duty truck being driven on a chassis dynamometer. The heavy-duty chassis dynamometer at the ReFUEL Laboratory simulates on-road driving in a controlled laboratory setting. Photo by Dennis Schroeder, NREL NREL's Renewable Fuels and Lubricants (ReFUEL) Laboratory is a state-of-the-art research and testing facility for advanced fuels and vehicles. Research and development focuses on overcoming barriers to the increased use of renewable

  5. NREL: Transportation Research - Fuel Combustion and Engine Performance

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Fuel Combustion and Engine Performance Photo of a gasoline direct injection piston with injector. NREL studies the effects of new fuel properties on performance and emissions in advanced engine technologies. Photo by Dennis Schroeder, NREL NREL's combustion research and development bridges fundamental chemical kinetics and applied engine research to investigate how new engine technologies can be co-developed with fuels and lubricants to maximize energy-efficient vehicle performance. Through

  6. NREL: Transportation Research - Power Electronics and Electric Machines

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Power Electronics and Electric Machines A photo of a researcher using testing equipment in a lab. NREL R&D is making wide-scale adoption of electric-drive vehicles more feasible by developing technologies and components with superior reliability, efficiency, and durability, while dramatically decreasing costs. Photo by Dennis Schroeder, NREL NREL's power electronics and electric machines research focuses on systems for electric-drive vehicles (EDVs) that control the flow of electricity

  7. Lessons learned from bacterial transport research at the South Oyster Site

    SciTech Connect

    Scheibe, T.; Hubbard, S.S.; Onstott, T.C.; DeFlaun, M.F.

    2011-04-01

    This paper provides a review of bacterial transport experiments conducted by a multi-investigator, multi-institution, multi-disciplinary team of researchers under the auspices of the U. S. Department of Energy (DOE). The experiments were conducted during the time period 1999-2001 at a field site near the town of Oyster, Virginia known as the South Oyster Site, and included four major experimental campaigns aimed at understanding and quantifying bacterial transport in the subsurface environment. Several key elements of the research are discussed here: (1) quantification of bacterial transport in physically, chemically and biologically heterogeneous aquifers, (2) evaluation of the efficacy of conventional colloid filtration theory, (3) scale effects in bacterial transport, (4) development of new methods for microbial enumeration and screening for low adhesion strains, (5) application of novel hydrogeophysical techniques for aquifer characterization, and (6) experiences regarding management of a large field research effort. Lessons learned are summarized in each of these areas. The body of literature resulting from South Oyster Site research has been widely cited and continues to influence research into the controls exerted by aquifer heterogeneity on reactive transport (including microbial transport). It also served as a model (and provided valuable experience) for subsequent and ongoing highly-instrumented field research efforts conducted by DOE-sponsored investigators.

  8. RKKY interaction in a chirally coupled double quantum dot system

    SciTech Connect

    Heine, A. W.; Tutuc, D.; Haug, R. J.; Zwicknagl, G.; Schuh, D.; Wegscheider, W.

    2013-12-04

    The competition between the Kondo effect and the Ruderman-Kittel-Kasuya-Yoshida (RKKY) interaction is investigated in a double quantum dots system, coupled via a central open conducting region. A perpendicular magnetic field induces the formation of Landau Levels which in turn give rise to the so-called Kondo chessboard pattern in the transport through the quantum dots. The two quantum dots become therefore chirally coupled via the edge channels formed in the open conducting area. In regions where both quantum dots exhibit Kondo transport the presence of the RKKY exchange interaction is probed by an analysis of the temperature dependence. The thus obtained Kondo temperature of one dot shows an abrupt increase at the onset of Kondo transport in the other, independent of the magnetic field polarity, i.e. edge state chirality in the central region.

  9. Quantum Dot Materials Can Reduce Heat, Boost Electrical Output...

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Quantum Dot Materials Can Reduce Heat, Boost Electrical Output May 23, 2005 Golden, Colo. - Researchers at the U.S. Department of Energy's National Renewable Energy Laboratory ...

  10. NREL: Transportation Research - NREL Serves as the Energy Department's

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Showcase for Cutting-Edge Fuel Cell Cars Serves as the Energy Department's Showcase for Cutting-Edge Fuel Cell Cars Research Studies Fueling System, Driver Behavior, and Vehicle Performance January 25, 2016 The Energy Department's National Renewable Energy Laboratory (NREL) recently received a 2015 Tucson Fuel Cell vehicle on loan from Hyundai through a one-year Cooperative Research and Development Agreement and a B-Class F-CELL on loan from Mercedes-Benz to support a one-year Technical

  11. Test and evaluation document for DOT Specification 7A type A packaging. Volume 1

    SciTech Connect

    Kelly, D L

    1997-08-04

    The US Department of Energy (DOE) has been conducting, through several of its operating contractors, an evaluation and testing program to qualify Type A radioactive material packagings per US Department of Transportation (DOT) Specification 7A (DOT-7A) of the Code of Federal Regulations (CFR), Title 49, Part 178 (49 CFR 178). This document summarizes the evaluation and testing performed for all of the packagings successfully qualified in this program. This document supersedes DOE Evaluation Document for DOT-7A Type A Packaging (Edling 1987), originally issued in 1987 by Monsanto Research Corporation Mound Laboratory (MLM), Miamisburg, Ohio, for the Department of Energy, Security Evaluation Program (I)P-4. Mound Laboratory issued four revisions to the document between November 1988 and December 1989. In September 1989, the program was transferred to Westinghouse Hanford Company (Westinghouse Hanford) in Richland, Washington. One additional revision was issued in March 1990 by Westinghouse Hanford. This revision reflects the earlier material and incorporates a number of changes. Evaluation and testing activities on 1208 three DOT-7A Program Dockets resulted in the qualification of three new packaging configurations, which are incorporated herein and summarized. This document presents approximately 300 different packagings that have been determined to meet the requirements for a DOT-7A, type A packaging per 49 CFR 178.350.

  12. NREL: Transportation Research - From Pump to Plug: Measuring the Public's

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Attitude about Plug-In Electric Vehicles From Pump to Plug: Measuring the Public's Attitude about Plug-In Electric Vehicles April 4, 2016 Vehicle manufacturers, U.S. Department of Energy laboratories, universities, private researchers, and other organizations from around the globe are pursuing advanced vehicle technologies that aim to reduce petroleum consumption. However, the broad acceptance of these technologies depends on consumer sentiment -- drivers must be willing to purchase such

  13. NREL: Transportation Research - Heavy-Duty Vehicle Thermal Management

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Heavy-Duty Vehicle Thermal Management Infrared image of a semi cab and two people. NREL testing and modeling assess the energy saving impact of advanced climate control materials and equipment on heavy-duty vehicles. Photo by Dennis Schroeder, NREL Illustration of a truck with labeled energy-saving elements. NREL researchers assess the energy saving potential of films, paints, advanced insulation, micro-environmental design, and idle reduction technologies. Illustration by Ray David, NREL

  14. NREL: Transportation Research - Light-Duty Vehicle Thermal Management

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Light-Duty Vehicle Thermal Management Image of a semi-transparent car with parts of the engine highlighted in green. NREL evaluates technologies and methods such as advanced window glazing, cooling heat-pipe systems, parked car ventilation, and direct energy recovery. Illustration by Josh Bauer, NREL National Renewable Energy Laboratory (NREL) researchers are focused on improving the thermal efficiency of light-duty vehicles (LDVs) while maintaining the thermal comfort that drivers expect.

  15. NREL: Transportation Research - Meeting Explores Global Advancement in

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Vehicle-To-Everything Integration Meeting Explores Global Advancement in Vehicle-To-Everything Integration June 3, 2016 NREL recently hosted the two-day V2X Enabled Electric Vehicles expert meeting, one of several that have been organized under the International Energy Agency's Hybrid & Electric Vehicle Implementing Agreement (IA-HEV) "Task 28" portfolio. Task 28 encompasses research and collaboration for deployment of home grids and vehicle-to-everything (V2X) technologies --

  16. NREL: Transportation Research - Vehicle Thermal Management Models and Tools

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Models and Tools image of three models of semi truck cabs. Truck cab models drawn from CAD geometry using CoolCalc (left and center), and a model with overlay of computational fluid dynamics flow (right) indicate areas of heat absorption and loss. Illustrations by Jason Lustbader, Matt Jeffers, and Larry Chaney, NREL The National Renewable Energy Laboratory's (NREL's) vehicle thermal management modeling tools allow researchers to assess the trade-offs and calculate the potential benefits of

  17. NREL: Transportation Research - NREL Issued Patent for Award-Winning

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Isothermal Battery Calorimeters Issued Patent for Award-Winning Isothermal Battery Calorimeters Researcher holding small battery pack in large-volume testing chamber. NREL's large-volume Isothermal Battery Calorimeter (IBC), coupled with its accuracy, allows for precise thermal measurements for safer, longer-lasting, and more cost-effective batteries for vehicles. November 1, 2016 The National Renewable Energy Laboratory (NREL) was recently issued a patent for its R&D 100 Award-winning

  18. Transportation

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Transportation Resources Policies, Manuals & References Map Transportation Publications ⇒ Navigate Section Resources Policies, Manuals & References Map Transportation Publications View Larger Map Main Address 1 Cyclotron Rd‎ University of California Berkeley Berkeley, CA 94720 The Laboratory is in Berkeley on the hillside directly above the campus of the University of California at Berkeley. Our address is 1 Cyclotron Road, Berkeley CA 94720. To make the Lab easily accessible, the

  19. Efficient charge transfer and field-induced tunneling transport in hybrid composite device of organic semiconductor and cadmium telluride quantum dots

    SciTech Connect

    Varade, Vaibhav Jagtap, Amardeep M.; Koteswara Rao, K. S. R.; Ramesh, K. P.; Menon, R.; Anjaneyulu, P.

    2015-06-07

    Temperature and photo-dependent current–voltage characteristics are investigated in thin film devices of a hybrid-composite comprising of organic semiconductor poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) and cadmium telluride quantum dots (CdTe QDs). A detailed study of the charge injection mechanism in ITO/PEDOT:PSS-CdTe QDs/Al device exhibits a transition from direct tunneling to Fowler–Nordheim tunneling with increasing electric field due to formation of high barrier at the QD interface. In addition, the hybrid-composite exhibits a huge photoluminescence quenching compared to aboriginal CdTe QDs and high increment in photoconductivity (∼ 400%), which is attributed to the charge transfer phenomena. The effective barrier height (Φ{sub B} ≈ 0.68 eV) is estimated from the transition voltage and the possible origin of its variation with temperature and photo-illumination is discussed.

  20. NREL: Transportation Research - New Funds to Help NREL Commercialize

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Compact, Power-Dense Inverters for Electric-Drive Vehicles New Funds to Help NREL Commercialize Compact, Power-Dense Inverters for Electric-Drive Vehicles August 2, 2016 As part of the new Technology Commercialization Fund (TCF), the U.S. Department of Energy (DOE) has awarded funding to the National Renewable Energy Laboratory (NREL) to lead a vehicle research and development (R&D) project in collaboration with John Deere Electronic Solutions (JDES). The funds will be used to apply

  1. Scalable quantum computer architecture with coupled donor-quantum dot qubits

    SciTech Connect

    Schenkel, Thomas; Lo, Cheuk Chi; Weis, Christoph; Lyon, Stephen; Tyryshkin, Alexei; Bokor, Jeffrey

    2014-08-26

    A quantum bit computing architecture includes a plurality of single spin memory donor atoms embedded in a semiconductor layer, a plurality of quantum dots arranged with the semiconductor layer and aligned with the donor atoms, wherein a first voltage applied across at least one pair of the aligned quantum dot and donor atom controls a donor-quantum dot coupling. A method of performing quantum computing in a scalable architecture quantum computing apparatus includes arranging a pattern of single spin memory donor atoms in a semiconductor layer, forming a plurality of quantum dots arranged with the semiconductor layer and aligned with the donor atoms, applying a first voltage across at least one aligned pair of a quantum dot and donor atom to control a donor-quantum dot coupling, and applying a second voltage between one or more quantum dots to control a Heisenberg exchange J coupling between quantum dots and to cause transport of a single spin polarized electron between quantum dots.

  2. Nanoscale engineering boosts performance of quantum dot light emitting

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    diodes Quantum dot light emitting diodes Nanoscale engineering boosts performance of quantum dot light emitting diodes Quantum dots are nano-sized semiconductor particles whose emission color can be tuned by simply changing their dimensions. October 25, 2013 Postdoctoral researcher Young-Shin Park characterizing emission spectra of LEDs in the Los Alamos National Laboratory optical laboratory. Postdoctoral researcher Young-Shin Park characterizing emission spectra of LEDs in the Los Alamos

  3. Summary of the FY 2005 Batteries for Advanced Transportation Technologies (BATT) Research Program Annual Review

    Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)

    the FY 2005 Batteries for Advanced Transportation Technologies (BATT) Research Program Annual Review May 31-June 2, 2005 Berkeley, CA August 2005 U.S. Department of Energy Office of FreedomCAR and Vehicle Technologies August 8, 2005 Dear Colleague: This document presents a summary of the evaluation and comments provided by the review panel for the FY 2005 Department of Energy (DOE) Batteries for Advanced Transportation Technologies (BATT) program annual review. The review was held at the

  4. transportation

    National Nuclear Security Administration (NNSA)

    security missions undertaken by the U.S. government.

    Pantex Plant's Calvin Nelson honored as Analyst of the Year for Transportation Security http:nnsa.energy.gov...

  5. 'Giant' Nanocrystal Quantum Dots

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    'Giant' Nanocrystal Quantum Dots - Sandia Energy Energy Search Icon Sandia Home Locations Contact Us Employee Locator Energy & Climate Secure & Sustainable Energy Future Stationary ...

  6. New Los Alamos approach may be key to quantum dot solar cells...

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Researchers have demonstrated an almost four-fold boost of the carrier multiplication yield with nanoengineered quantum dots. June 18, 2014 Coreshell PbSeCdSe quantum dots (a) ...

  7. Chevron and NREL to Collaborate on Research to Produce Transportation Fuels

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    using Algae - News Releases | NREL Chevron and NREL to Collaborate on Research to Produce Transportation Fuels using Algae Joint effort to identify and develop algae strains for feedstock in next-generation biofuels October 31, 2007 Chevron Corporation (NYSE: CVX) and the U.S. Department of Energy's National Renewable Energy Laboratory (NREL) announced today that they have entered into a collaborative research and development agreement to study and advance technology to produce liquid

  8. Research and Development Program for transportation packagings at Sandia National Laboratories

    SciTech Connect

    Hohnstreiter, G.F.; Sorenson, K.B.

    1995-02-01

    This document contains information about the research and development programs dealing with waste transport at Sandia National Laboratories. This paper discusses topics such as: Why new packaging is needed; analytical methodologies and design codes;evaluation of packaging components; materials characterization; creative packaging concepts; packaging engineering and analysis; testing; and certification support.

  9. Ambipolar quantum dots in intrinsic silicon

    SciTech Connect

    Betz, A. C. Gonzalez-Zalba, M. F.; Podd, G.; Ferguson, A. J.

    2014-10-13

    We electrically measure intrinsic silicon quantum dots with electrostatically defined tunnel barriers. The presence of both p- and n-type ohmic contacts enables the accumulation of either electrons or holes. Thus, we are able to study both transport regimes within the same device. We investigate the effect of the tunnel barriers and the electrostatically defined quantum dots. There is greater localisation of charge states under the tunnel barriers in the case of hole conduction, leading to higher charge noise in the p-type regime.

  10. Quantum Dots: Theory

    SciTech Connect

    Vukmirovic, Nenad; Wang, Lin-Wang

    2009-11-10

    This review covers the description of the methodologies typically used for the calculation of the electronic structure of self-assembled and colloidal quantum dots. These are illustrated by the results of their application to a selected set of physical effects in quantum dots.

  11. WIPP Documents - Transportation

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Transportation

  12. Letter to Science from Michael Wang, Center for Transportation Research, Argonne National Laboratory

    Alternative Fuels and Advanced Vehicles Data Center

    Letter to Science (Original version submitted to Science on Feb. 14 th , 2008; revised on March 14 th , 2008) Michael Wang Center for Transportation Research Argonne National Laboratory Zia Haq Office of Biomass Program Office of Energy Efficiency and Renewable Energy U.S. Department of Energy The article by Searchinger et al. in Sciencexpress ("Use of U.S. Croplands for Biofuels Increases Greenhouse Gases through Emissions from Land Use Change," February 7, 2008) provides a timely

  13. Improvement in carrier transport properties by mild thermal annealing...

    Office of Scientific and Technical Information (OSTI)

    quantum dot solar cells Citation Details In-Document Search Title: Improvement in carrier transport properties by mild thermal annealing of PbS quantum dot solar cells Authors: ...

  14. Operational guidance for using DOT-6M/2R packaging

    SciTech Connect

    Kelly, D.L.; Hummer, J.H.

    1994-03-01

    The purpose of this paper is to describe a new US Department of Energy (DOE), Transportation Management Division task to create a US Department of Transportation (DOT) Specification 6M/2R packaging configuration user`s guide. The need for a user`s guide was identified because the DOT-6M/2R packaging configuration is widely used by DOE site contractors, and DOE receives many questions about the approved packaging configurations. Currently, two DOE organizations have the authority to approve new DOT-6M/2R configurations. For Defense Programs, the Transportation and Packaging Safety Division (EH-332) administers the program. For Environmental Restoration and Waste Management, the Transportation Management Division (EM-261) administers the program.

  15. US Department of Transportation (DOT) Spec 7A Type A evaluation document: Spec 17C 55-gal steel drum with RWMC/SWEPP drum venting system carbon filter assembly

    SciTech Connect

    Edling, D.A.

    1986-09-15

    As part of MRC-Mound's responsibility to coordinate DOE Spec 7A Type A Packaging testing, evaluation, and utilization, this document evaluates per 49CFR 173.415(a) the SWEPP packaging system: DOT Spec 17C steel drums - 30, 55 and 83-gal; High Density Polyethylene (HDPE) liners; and SWEPP DVS Filter Assemblies (two configurations) as a US DOT Spec 7A Type A packaging. A variety of Type A performance testing was done on: DOT Spec 17C 55-gal steel drums; DOT Spec 17C 55-gal steel drums with HDPE liners; and DOT Spec 17C 55-gal steel drums with ''Nucfil'' filters as part of MRC-Mound's Type A Packaging Evaluation Program funded by DOE/HQ, DP-4, Security Evaluations. The subject SWEPP packaging incorporates modifications to the ''Nucfil'' filter and installation assembly previously tested in conjunction with the Spec 17C 55-gal drums. Thus, additional testing was required on the new filter installation in order to evaluate the entire packaging system. This document presents the test data to demonstrate the SWEPP packaging system's performance against the DOT 7A Type A requirements.

  16. A reconfigurable gate architecture for Si/SiGe quantum dots

    SciTech Connect

    Zajac, D. M.; Hazard, T. M.; Mi, X.; Wang, K.; Petta, J. R.

    2015-06-01

    We demonstrate a reconfigurable quantum dot gate architecture that incorporates two interchangeable transport channels. One channel is used to form quantum dots, and the other is used for charge sensing. The quantum dot transport channel can support either a single or a double quantum dot. We demonstrate few-electron occupation in a single quantum dot and extract charging energies as large as 6.6 meV. Magnetospectroscopy is used to measure valley splittings in the range of 35–70 μeV. By energizing two additional gates, we form a few-electron double quantum dot and demonstrate tunable tunnel coupling at the (1,0) to (0,1) interdot charge transition.

  17. Testing of a Transport Cask for Research Reactor Spent Fuel - 13003

    SciTech Connect

    Mourao, Rogerio P.; Leite da Silva, Luiz; Miranda, Carlos A.; Mattar Neto, Miguel; Quintana, Jose F.A.; Saliba, Roberto O.; Novara, Oscar E.

    2013-07-01

    Since the beginning of the last decade three Latin American countries that operate research reactors - Argentina, Brazil and Chile - have been joining efforts to improve the regional capability in the management of spent fuel elements from the TRIGA and MTR reactors operated in the region. A main drive in this initiative, sponsored by the International Atomic Energy Agency, is the fact that no definite solution regarding the back end of the research reactor fuel cycle has been taken by any of the participating country. However, any long-term solution - either disposition in a repository or storage away from reactor - will involve at some stage the transportation of the spent fuel through public roads. Therefore, a licensed cask that provides adequate shielding, assurance of subcriticality, and conformance to internationally accepted safety, security and safeguards regimes is considered a strategic part of any future solution to be adopted at a regional level. As a step in this direction, a packaging for the transport of irradiated fuel for MTR and TRIGA research reactors was designed by the tri-national team and a half-scale model equipped with the MTR version of the internal basket was constructed in Argentina and Brazil and tested in Brazil. Three test campaigns have been carried out so far, covering both normal conditions of transportation and hypothetical accident conditions. After failing the tests in the first two test series, the specimen successfully underwent the last test sequence. A second specimen, incorporating the structural improvements in view of the previous tests results, will be tested in the near future. Numerical simulations of the free drop and thermal tests are being carried out in parallel, in order to validate the computational modeling that is going to be used as a support for the package certification. (authors)

  18. Solution-Processed Solar Cells using Colloidal Quantum Dots ...

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Solution-Processed Solar Cells using Colloidal Quantum Dots September 27, 2012 at 3pm36-428 Ted Sargent Department of Electrical and Computer Engineering - Canada Research Chair ...

  19. DOT-7A packaging test procedure

    SciTech Connect

    Kelly, D.L.

    1995-01-23

    This test procedure documents the steps involved with performance testing of Department of Transportation Specification 7A (DOT-7A) Type A packages. It includes description of the performance tests, the personnel involved, appropriate safety considerations, and the procedures to be followed while performing the tests. Westinghouse Hanford Company (WHC) is conducting the evaluation and testing discussed herein for the Department of Energy-Headquarters, Division of Quality Verification and Transportation Safety (EH-321). Please note that this report is not in WHC format. This report is being submitted through the Engineering Documentation System so that it may be used for reference and information purposes.

  20. NRC Technical Research Program to Evaluate Extended Storage and Transportation of Spent Nuclear Fuel - 12547

    SciTech Connect

    Einziger, R.E.; Compton, K.; Gordon, M.; Ahn, T.; Gonzales, H.; Pan, Y.

    2012-07-01

    Any new direction proposed for the back-end of spent nuclear fuel (SNF) cycle will require storage of SNF beyond the current licensing periods. The Nuclear Regulatory Commission (NRC) has established a technical research program to determine if any changes in the 10 CFR part 71, and 72 requirements, and associated guidance might be necessary to regulate the safety of anticipated extended storage, and subsequent transport of SNF. This three part program of: 1) analysis of knowledge gaps in the potential degradation of materials, 2) short-term research and modeling, and 3) long-term demonstration of systems, will allow the NRC to make informed regulatory changes, and determine when and if additional monitoring and inspection of the systems is necessary. The NRC has started a research program to obtain data necessary to determine if the current regulatory guidance is sufficient if interim dry storage has to be extended beyond the currently approved licensing periods. The three-phased approach consists of: - the identification and prioritization of potential degradation of the components related to the safe operation of a dry cask storage system, - short-term research to determine if the initial analysis was correct, and - a long-term prototypic demonstration project to confirm the models and results obtained in the short-term research. The gap analysis has identified issues with the SCC of the stainless steel canisters, and SNF behavior. Issues impacting the SNF and canister internal performance such as high and low temperature distributions, and drying have also been identified. Research to evaluate these issues is underway. Evaluations have been conducted to determine the relative values that various types of long-term demonstration projects might provide. These projects or follow-on work is expected to continue over the next five years. (authors)

  1. Geometric spin manipulation in semiconductor quantum dots

    SciTech Connect

    Prabhakar, Sanjay Melnik, Roderick; Inomata, Akira

    2014-04-07

    We propose a method to flip the spin completely by an adiabatic transport of quantum dots. We show that it is possible to flip the spin by inducing a geometric phase on the spin state of a quantum dot. We estimate the geometric spin flip time (approximately 2 ps) which turned out to be much shorter than the experimentally reported decoherence time (approximately 100 ns) that would provide an alternative means of fliping the spin before reaching decoherence. It is important that both the Rashba coupling and the Dresselhaus coupling are present for inducing a phase necessary for spin flip. If one of them is absent, the induced phase is trivial and irrelevant for spin-flip.

  2. Quality Assurance Plan for Transportation Management Division Transportation Training Programs

    SciTech Connect

    Not Available

    1994-10-01

    The U.S. Department of Transportation (DOT) implemented new rules requiring minimum levels of training for certain key individuals who handle, package, transport, or otherwise prepare hazardous materials for transportation. In response to these rules, the U.S. Department of Energy (DOE), Transportation Management Division (TMD), has developed a transportation safety training program. This program supplies designed instructional methodology and course materials to provide basic levels of DOT training to personnel for whom training has become mandatory. In addition, this program provides advanced hazardous waste and radioactive material packaging and transportation training to help personnel achieve proficiency and/or certification as hazardous waste and radioactive material shippers. This training program does not include site-specific or task-specific training beyond DOT requirements.

  3. Quantum-dot solar windows evolve with 'doctor-blade' spreading

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Quantum-dot solar windows evolve with 'doctor-blade' spreading Quantum-dot solar windows evolve with 'doctor-blade' spreading A Los Alamos National Laboratory research team demonstrates an important step in taking quantum dot, solar-powered windows from the laboratory to the construction site. October 11, 2016 Los Alamos Center for Advanced Solar Photophysics researchers hold a large prototype solar window. From left to right: Jaehoon Lim, Kaifeng Wu, Victor Klimov, Hongbo Li. Los Alamos Center

  4. Quantum-dot solar windows evolve with 'doctor-blade' spreading

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Quantum-dot solar windows evolve with 'doctor-blade' spreading At the Bradbury Latest Issue:November 2016 all issues All Issues » submit Quantum-dot solar windows evolve with 'doctor-blade' spreading A Los Alamos National Laboratory research team demonstrates an important step in taking quantum dot, solar-powered windows from the laboratory to the construction site. November 1, 2016 Los Alamos Center for Advanced Solar Photophysics researchers hold a large prototype solar window. From left to

  5. Surface Transportation Research and Development Act of 1997. House of Representatives, One Hundred Fifth Congress, Second Session

    SciTech Connect

    1998-12-31

    Mr. Sensenbrenner, from the Committee on Science, submitted this report together with additional views. The Committee on Science, to whom was referred the bill (H.R. 860) to authorize appropriations to the Department of Transportation for surface transportation research and development, and for other purposes, having considered the same, report favorably thereon with an amendment and recommend that the bill as amended do pass.

  6. 49 CFR Parts 171-177: Hazardous Materials Regulations (DOT) | Department of

    Energy Saver

    Energy 71-177: Hazardous Materials Regulations (DOT) 49 CFR Parts 171-177: Hazardous Materials Regulations (DOT) The U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration regulates the transport of hazardous materials through Title 49 of the Code of Federal Regulations (49 CFR), Subchapter C, "Hazardous Materials Regulations." Parts 171-177 provide general information on hazardous materials and regulation for their packaging and their shipment by

  7. The effect of Coulomb interactions on thermoelectric properties of quantum dots

    SciTech Connect

    Zimbovskaya, Natalya A.

    2014-03-14

    Thermoelectric effects in a quantum dot coupled to the source and drain charge reservoirs are explored using a nonequilibrium Green's functions formalism beyond the Hartree-Fock approximation. Thermal transport is analyzed within a linear response regime. A transition from Coulomb blockade regime to Kondo regime in thermoelectric transport through a single-level quantum dot is traced using unified approximations for the relevant Green's functions.

  8. Relaxation dynamics in correlated quantum dots

    SciTech Connect

    Andergassen, S.; Schuricht, D.; Pletyukhov, M.; Schoeller, H.

    2014-12-04

    We study quantum many-body effects on the real-time evolution of the current through quantum dots. By using a non-equilibrium renormalization group approach, we provide analytic results for the relaxation dynamics into the stationary state and identify the microscopic cutoff scales that determine the transport rates. We find rich non-equilibrium physics induced by the interplay of the different energy scales. While the short-time limit is governed by universal dynamics, the long-time behavior features characteristic oscillations as well as an interplay of exponential and power-law decay.

  9. NREL Certifies First All-Quantum-Dot Photovoltaic Cell; Demonstrates Stability, Performance (Fact Sheet)

    SciTech Connect

    Not Available

    2011-02-01

    Researchers at the National Renewable Energy Laboratory (NREL) have certified the first all-quantum-dot photovoltaic cell, which was based on lead sulfide and demonstrated reasonable quantum dot solar cell performance for an initial efficiency measurement along with good stability. The certified open-circuit voltage of the quantum dot cell is greater than that possible from bulk lead sulfide because of quantum confinement.

  10. Transportation Secure Data Center: Real-World Data for Transportation Planning and Land Use Analysis (Fact Sheet)

    SciTech Connect

    Not Available

    2013-01-01

    The National Renewable Energy Laboratory (NREL) and the U.S. Department of Transportation (DOT) have launched the free, web-based Transportation Secure Data Center (TSDC). The TSDC (www.nrel.gov/tsdc) preserves respondent anonymity while making vital transportation data available to a broad group of users through secure, online access. The TSDC database provides free-of-charge web-based access to valuable transportation data that can be used for: Transit planning, Travel demand modeling, Homeland Security evacuation planning, Alternative fuel station planning, and Validating transportation data from other sources. The TSDC's two levels of access make composite data available with simple online registration, and allow researchers to use detailed spatial data after completing a straight forward application process.

  11. NREL: Transportation Research - NREL Describes to U.S. Senate Role National

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Labs Play in Sustainable Transportation Innovation Describes to U.S. Senate Role National Labs Play in Sustainable Transportation Innovation January 26, 2016 On Thursday, January 21, 2016, NREL's Transportation and Hydrogen Systems Center Director Chris Gearhart provided a testimony on new technologies in the automobile industry before the U.S. Senate Energy and Natural Resources Committee. Members of the committee are currently evaluating a bipartisan bill that will include several

  12. Chamber transport

    SciTech Connect

    OLSON,CRAIG L.

    2000-05-17

    Heavy ion beam transport through the containment chamber plays a crucial role in all heavy ion fusion (HIF) scenarios. Here, several parameters are used to characterize the operating space for HIF beams; transport modes are assessed in relation to evolving target/accelerator requirements; results of recent relevant experiments and simulations of HIF transport are summarized; and relevant instabilities are reviewed. All transport options still exist, including (1) vacuum ballistic transport, (2) neutralized ballistic transport, and (3) channel-like transport. Presently, the European HIF program favors vacuum ballistic transport, while the US HIF program favors neutralized ballistic transport with channel-like transport as an alternate approach. Further transport research is needed to clearly guide selection of the most attractive, integrated HIF system.

  13. DOT-7A Type A packaging design guide

    SciTech Connect

    Kelly, D.L.

    1995-01-23

    The purpose of this Design Guide is to provide instruction for designing a U.S. Department of Transportation Specification 7A (DOT-7A) Type A packaging. Another purpose for this Design Guide is to support the evaluation and testing activities that are performed on new designs by a U.S. Department of Energy (DOE) test facility. This evaluation and testing program is called the DOT-7A Program. When an applicant has determined that a DOT-7A packaging is needed and not commercially available, a design may be created according to this document. The design should include a packaging drawing, specifications, analysis report, operating instructions, and a Packaging Qualification Checklist; all of which should be forwarded to a DOE/HQ approved test facility for evaluation and testing. This report is being submitted through the Engineering Documentation System so that it may be used for reference and information purposes.

  14. Out-of-Equilibrium Kondo Effect in Double Quantum Dots

    SciTech Connect

    Aguado, Ramon; Langreth, David C.

    2000-08-28

    The out-of-equilibrium transport properties of a double quantum dot system in the Kondo regime are studied theoretically by means of a two-impurity Anderson Hamiltonian with interimpurity hopping. The Hamiltonian is solved by means of a nonequilibrium generalization of the slave-boson mean-field theory. It is demonstrated that measurements of the differential conductance dI/dV , for appropriate values of voltages and tunneling couplings, can give a direct observation of the coherent superposition between the many-body Kondo states of each dot. For large voltages and arbitrarily large interdot tunneling, there is a critical voltage above which the physical behavior of the system again resembles that of two decoupled quantum dots. (c) 2000 The American Physical Society.

  15. A prototype silicon double quantum dot with dispersive microwave readout

    SciTech Connect

    Schmidt, A. R. Henry, E.; Namaan, O.; Siddiqi, I.; Lo, C. C.; Wang, Y.-T.; Bokor, J.; Yablonovitch, E.; Li, H.; Greenman, L.; Whaley, K. B.; Schenkel, T.

    2014-07-28

    We present a unique design and fabrication process for a lateral, gate-confined double quantum dot in an accumulation mode metal-oxide-semiconductor (MOS) structure coupled to an integrated microwave resonator. All electrostatic gates for the double quantum dot are contained in a single metal layer, and use of the MOS structure allows for control of the location of the two-dimensional electron gas via the location of the accumulation gates. Numerical simulations of the electrostatic confinement potential are performed along with an estimate of the coupling of the double quantum dot to the microwave resonator. Prototype devices are fabricated and characterized by transport measurements of electron confinement and reflectometry measurements of the microwave resonator.

  16. Quantum-dot solar windows evolve with 'doctor-blade' spreading

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Quantum-dot solar windows evolve with 'doctor-blade' spreading Quantum-dot solar windows evolve with 'doctor-blade' spreading Los Alamos scientists report on large LSC windows created using the "doctor-blade" technique for depositing thin layers of a dot/polymer composite on top of commercial large-area glass slab. November 4, 2016 Quantum-dot solar windows evolve with 'doctor-blade' spreading Los Alamos Center for Advanced Solar Photophysics researchers hold a large prototype solar

  17. Towards the future: The promise of intermodal and multimodal transportation systems. Research report

    SciTech Connect

    Anderson, S.E.; Easley, R.B.; Fowler, T.M.; Gabler, W.L.; Govind, S.

    1995-02-01

    Issues relating to intermodal and multimodal transportation systems are introduced and defined. Intermodal and multimodal transportation solutions are assessed within the framework of legislative efforts such as Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA), Clean Air Act Amendments of 1990 (CAAA), and North American Free Trade Agreement (NAFTA). Federal involvement in state intermodal transportation systems, and state responses to the growing intermodal and multimodal trends are also reviewed. The roles and responsibilities of the Metropolitan Planning Organizations (MPO) in the post-ISTEA world is examined and the impacts of legislative mandates considered. As a case study, the workings of the Houston MPO are examined. Private sector intermodal and multimodal involvement is addressed, including issues in management, regulatory, financial, economical, environmental, and even physical constraints. Effects of regulation on private sector intermodalism are discussed, as are case studies in partnering and management.

  18. Summary of the FY 2005 Batteries for Advanced Transportation Technologies (BATT) research program annual review

    SciTech Connect

    None, None

    2005-08-01

    This document presents a summary of the evaluation and comments provided by the review panel for the FY 2005 Department of Energy (DOE) Batteries for Advanced Transportation Technologies (BATT) program annual review.

  19. Dallas area-wide intelligent transportation system plan. Draft research report, August 1992-August 1996

    SciTech Connect

    Carvell, J.D.; Seymour, E.J.; Walters, C.H.; Starr, T.R.; Balke, K.

    1996-07-01

    This report documents the development of a comprehensive plan for implementation of Intelligent Transportation Systems (ITS) in the Dallas Urban Area. The contract defined objectives: Develop a Broadly Based Steering Committee; Assess Existing Transportation Management Systems and Potential ITS Technology; Identify Institutional Issues and Legal Barriers; Develop an Implementable, Area-Wide Multi-Jurisdictional ITS Plan; and Develop Cost, Benefits, and an Implementation Plan.

  20. Nanoscale engineering boosts performance of quantum dot light...

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Quantum dot light emitting diodes Nanoscale engineering boosts performance of quantum dot light emitting diodes Quantum dots are nano-sized semiconductor particles whose emission ...

  1. Few Electron Quantum Dot coupling ...

    Office of Scientific and Technical Information (OSTI)

    Electron Quantum Dot coupling to Donor Implanted Electron Spins Martin Rudolph1. P. Harvey-Collard12, E. Nielson1, J.K. Gamble1, R. Muller1, T. Jacobson1, G. Ten-Eyck1, J. ...

  2. Regulatory compliance guide for DOT-7A type A packaging design

    SciTech Connect

    Kelly, D.L.

    1996-06-04

    The purpose of this guide is to provide instruction for assuring that the regulatory design requirements for a DOT-7A Type A packaging are met. This guide also supports the testing and evaluation activities that are performed on new packaging designs by a DOE-approved test facility through the DOE`s DOT-7A Test Program. This Guide was updated to incorporate regulatory changes implemented by HM-169A (49 CFR, `Transportation`).

  3. Enforcement Guidance Supplement 98-02: DOE Enforcement Activities where Off-site Transportation Issues are also Present.

    Energy.gov [DOE]

    Recently several questions have arisen regarding the scope of Price-Anderson enforcement when transportation issues are directly or indirectly involved in an incident. These questions can be separated into two areas, (1) transportation issues that involve on-site transportation typically not regulated by the Department of Transportation (DOT), and (2) transportation issues that involve off-site transportation. This guidance addresses off-site transportation that is regulated by DOT and other state and federal agencies.

  4. Computational models for the berry phase in semiconductor quantum dots

    SciTech Connect

    Prabhakar, S. Melnik, R. V. N.; Sebetci, A.

    2014-10-06

    By developing a new model and its finite element implementation, we analyze the Berry phase low-dimensional semiconductor nanostructures, focusing on quantum dots (QDs). In particular, we solve the Schrdinger equation and investigate the evolution of the spin dynamics during the adiabatic transport of the QDs in the 2D plane along circular trajectory. Based on this study, we reveal that the Berry phase is highly sensitive to the Rashba and Dresselhaus spin-orbit lengths.

  5. Single to quadruple quantum dots with tunable tunnel couplings

    SciTech Connect

    Takakura, T.; Noiri, A.; Obata, T.; Yoneda, J.; Yoshida, K.; Otsuka, T.; Tarucha, S.

    2014-03-17

    We prepare a gate-defined quadruple quantum dot to study the gate-tunability of single to quadruple quantum dots with finite inter-dot tunnel couplings. The measured charging energies of various double dots suggest that the dot size is governed by the gate geometry. For the triple and quadruple dots, we study the gate-tunable inter-dot tunnel couplings. For the triple dot, we find that the effective tunnel coupling between side dots significantly depends on the alignment of the center dot potential. These results imply that the present quadruple dot has a gate performance relevant for implementing spin-based four-qubits with controllable exchange couplings.

  6. NREL: Transportation Research - NREL Leads Effort to Get Traffic Moving in

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    the Right Direction NREL Leads Effort to Get Traffic Moving in the Right Direction Connected Traveler project will guide travelers in energy-efficient manner August 17, 2015 The Energy Department's National Renewable Energy Laboratory (NREL) will serve as the lead organization in developing a tool travelers and transportation officials can use in helping guide people through a city in the most energy-efficient way possible. "Using real-time traffic and GPS data, along with simulations

  7. Transportation Systems Modeling

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    TRACC RESEARCH Computational Fluid Dynamics Computational Structural Mechanics Transportation Systems Modeling TRANSPORTATION SYSTEMS MODELING Overview of TSM Transportation systems modeling research at TRACC uses the TRANSIMS (Transportation Analysis SIMulation System) traffic micro simulation code developed by the U.S. Department of Transportation (USDOT). The TRANSIMS code represents the latest generation of traffic simulation codes developed jointly under multiyear programs by USDOT, the

  8. Performance of a neutron transport code with full phase space decomposition on the Cray Research T3D

    SciTech Connect

    Dorr, M.R.; Salo, E.M.

    1995-01-01

    We present performance results obtained on a 128-node Cray Research T3D computer by a neutron transport code implementing a standard mtiltigroup, discrete ordinates algorithm on a three-dimensional Cartesian grid. After summarizing the implementation strategy used to obtain a full decomposition of phase space (i.e., simultaneous parallelization of the neutron energy, directional and spatial variables), we investigate the scalability of the fundamental source iteration step with respect to each phase space variable. We also describe enhancements that have enabled performance rates approaching 10 gigaflops on the full 128-node machine.

  9. Photocurrent extraction efficiency in colloidal quantum dot photovoltaics

    SciTech Connect

    Kemp, K. W.; Wong, C. T. O.; Hoogland, S. H.; Sargent, E. H.

    2013-11-18

    The efficiency of photocurrent extraction was studied directly inside operating Colloidal Quantum Dot (CQD) photovoltaic devices. A model was derived from first principles for a thin film p-n junction with a linearly spatially dependent electric field. Using this model, we were able to clarify the origins of recent improvement in CQD solar cell performance. From current-voltage diode characteristics under 1 sun conditions, we extracted transport lengths ranging from 39 nm to 86 nm for these materials. Characterization of the intensity dependence of photocurrent extraction revealed that the dominant loss mechanism limiting the transport length is trap-mediated recombination.

  10. Nonradiative Recombination Pathways in Noncarcinogenic Quantum Dot

    Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)

    Composites | Department of Energy Nonradiative Recombination Pathways in Noncarcinogenic Quantum Dot Composites Nonradiative Recombination Pathways in Noncarcinogenic Quantum Dot Composites Lead Performer: UbiQD, LLC - Los Alamos, NM DOE Total Funding: $150,000 Project Term: February 22, 2016 - November 21, 2016 Funding Type: SBIR PROJECT OBJECTIVE Quantum dots composed of I-III-VI materials such as CuInS2 offer a compelling alternative to typical semiconductor quantum-dot systems, because

  11. What the Blank Makes Quantum Dots Blink?

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    What the Blank Makes Quantum Dots Blink? What the Blank Makes Quantum Dots Blink? Calculations confirm that surface flaws are behind fluorescence intermittency in silicon nanocrystals June 15, 2015 Contact: Margie Wylie, mwylie@lbl.gov, +1 510 486 7421 Quantum dots are semiconductors just a few nanometers in diameter that can glow Quantum dots (shown here dissolved in liquid under ultraviolet light) offer tantalizing prospects for new technologies if scientists can stop them blinking. (Photo by

  12. Hazardous Materials Transportation Authorization Act of 1993. Introduced in the Senate of the United States. Report of the Senate Committee on Commerce, Science, and Transportation, One Hundred Third Congress, First Session

    SciTech Connect

    1993-12-31

    The report addresses a bill (S. 1640) to amend the Hazardous Materials Transportation Act (HMTA). The bill authorizes appropriations. This legislation would authorized funding of the HMTA by the Department of Transportation (DOT) as program manager. The DOT is required to take a number of significant steps to improve hazmat transportation safety. The legislative text of the Bill is summarized with amendments.

  13. Transportation Secure Data Center: Real-World Data for Environmental and Air Quality Analysis (Fact Sheet)

    SciTech Connect

    Not Available

    2013-01-01

    The National Renewable Energy Laboratory (NREL) and the U.S. Department of Transportation (DOT) have launched the free, web-based Transportation Secure Data Center (TSDC). The TSDC (www.nrel.gov/tsdc) preserves respondent anonymity while making vital transportation data available to a broad group of users through secure, online access. The TSDC database provides free-of-charge web-based access to valuable transportation data that can be used for: Emissions and air pollution modeling, Vehicle energy and power analysis, Climate change impact studies, Alternative fuel station planning, and Validating transportation data from other sources. The TSDC's two levels of access make composite data available with simple online registration, and allow researchers to use detailed spatial data after completing a straight forward application process.

  14. Reaction-based Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center

    SciTech Connect

    Tsyh Yeh, Gour

    2007-12-21

    This research sought to examine biogeochemical processes likely to take place in the less conductive materials above and below the gravel during the in situ ethanol biostimulation experiment conducted at Area 2 during 2005-2006. The in situ experiment in turn examined the hypothesis that injection of electron donor into this layer would induce formation of a redox barrier in the less conductive materials, resulting in decreased mass transfer of uranium out these materials and attendant declines in groundwater U(VI) concentration. Our project focuses on the development of a mechanistic understanding and quantitative models of coupled Fe(III)/U(VI) reduction in FRC Area 2 sediments. This report summarizes research activities conducted at The University of Central Florida (2004-2007), the development of biogeochemical and reactive transport models and the conduction of numerical simulations at laboratory, column, and field scales.

  15. Induced spin-accumulation and spin-polarization in a quantum-dot ring by using magnetic quantum dots and Rashba spin-orbit effect

    SciTech Connect

    Eslami, L. Faizabadi, E.

    2014-05-28

    The effect of magnetic contacts on spin-dependent electron transport and spin-accumulation in a quantum ring, which is threaded by a magnetic flux, is studied. The quantum ring is made up of four quantum dots, where two of them possess magnetic structure and other ones are subjected to the Rashba spin-orbit coupling. The magnetic quantum dots, referred to as magnetic quantum contacts, are connected to two external leads. Two different configurations of magnetic moments of the quantum contacts are considered; the parallel and the anti-parallel ones. When the magnetic moments are parallel, the degeneracy between the transmission coefficients of spin-up and spin-down electrons is lifted and the system can be adjusted to operate as a spin-filter. In addition, the accumulation of spin-up and spin-down electrons in non-magnetic quantum dots are different in the case of parallel magnetic moments. When the intra-dot Coulomb interaction is taken into account, we find that the electron interactions participate in separation between the accumulations of electrons with different spin directions in non-magnetic quantum dots. Furthermore, the spin-accumulation in non-magnetic quantum dots can be tuned in the both parallel and anti-parallel magnetic moments by adjusting the Rashba spin-orbit strength and the magnetic flux. Thus, the quantum ring with magnetic quantum contacts could be utilized to create tunable local magnetic moments which can be used in designing optimized nanodevices.

  16. Safety analysis report for packaging: the ORNL DOT specification 6M - special form package

    SciTech Connect

    Schaich, R.W.

    1982-07-01

    The ORNL DOT Specification 6M - Special Form Package was fabricated at the Oak Ridge Nation al Laboratory (ORNL) for the transport of Type B solid non-fissile radioactive materials in special form. The package was evaluated on the basis of tests performed by the Dow Chemical Company, Rocky Flats Division, on the DOT-6M container and special form tests performed on a variety of stainless steel capsules at ORNL by Operations Division personnel. The results of these evaluations demonstrate that the package is in compliance with the applicable regulations for the transport of Type B quantities in special form of non-fissile radioactive materials.

  17. Photo-induced conductance fluctuations in mesoscopic Ge/Si systems with quantum dots

    SciTech Connect

    Stepina, N. P.; Dvurechenskii, A. V.; Nikiforov, A. I.; Moers, J.; Gruetzmacher, D.

    2014-08-20

    We study the evolution of electron transport in strongly localized mesoscopic system with quantum dots under small photon flux. Exploring devices with narrow transport channels lead to the observation of giant fluctuations of the photoconductance, which is attributed to the strong dependence of hopping current on the filling of dots by holes. In our experiments, single-photon mode operation is indicated by the linear dependence of the frequency of photo-induced fluctuations on the light intensity and the step-like response of conductance on the pulse excitation. The effect of the light wavelength, measurement temperature, size of the conductive channel on the device efficiency are considered.

  18. New research, publications and videos

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    May issue of Community Connections New Video Portable MRI developed at Los Alamos Los Alamos Quantum Dots for Solar, Display Technology Disease Diagnostics Research at Los Alamos ...

  19. New research, publications and videos

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Researchers have demonstrated an almost four-fold boost of the carrier multiplication yield with nanoengineered quantum dots. Publications August issue of 1663: Los Alamos Science ...

  20. NREL: Transportation Research - New Study Reveals Impact of Auto Roof Racks

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    on Fuel Economy New Study Reveals Impact of Auto Roof Racks on Fuel Economy Picture of car with auto roof rack and boom in front of car. Toyota Corolla equipped for coast down test with a rooftop cargo box and boom. Photo courtesy of Oak Ridge National Laboratory. June 10, 2016 A recent study by NREL research engineer Yuche Chen and researcher Alan Meier at Lawrence Berkeley National Laboratory (LBNL) examined the national impact of roof racks on fuel consumption. In this first-of-its-kind

  1. Women @ Energy: Dot Harris | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)

    Dot Harris Women @ Energy: Dot Harris March 15, 2013 - 1:06pm Addthis LaDoris (Dot) Harris is the Director of the Office of Economic Impact and Diversity. LaDoris (Dot) Harris is the Director of the Office of Economic Impact and Diversity. LaDoris (Dot) Harris is the Director of the Office of Economic Impact and Diversity. She was nominated by President Obama and confirmed by the U.S. Senate on March 29, 2012. She has served at some of the world's largest firms including General Electric, ABB

  2. Modeling of the quantum dot filling and the dark current of quantum dot infrared photodetectors

    SciTech Connect

    Ameen, Tarek A.; El-Batawy, Yasser M.; Abouelsaood, A. A.

    2014-02-14

    A generalized drift-diffusion model for the calculation of both the quantum dot filling profile and the dark current of quantum dot infrared photodetectors is proposed. The confined electrons inside the quantum dots produce a space-charge potential barrier between the two contacts, which controls the quantum dot filling and limits the dark current in the device. The results of the model reasonably agree with a published experimental work. It is found that increasing either the doping level or the temperature results in an exponential increase of the dark current. The quantum dot filling turns out to be nonuniform, with a dot near the contacts containing more electrons than one in the middle of the device where the dot occupation approximately equals the number of doping atoms per dot, which means that quantum dots away from contacts will be nearly unoccupied if the active region is undoped.

  3. Caged Quantum Dots

    ScienceCinema

    Cohen, Bruce

    2013-05-29

    Berkeley Lab scientists have developed a nanosized crystal that lights up on command, a feat that could allow researchers to more easily observe individual proteins inside cells. http://newscenter.lbl.gov/feature-stories/2008/11/18/cagedquantumdots/

  4. DOE TMD transportation training module 14 transportation of explosives

    SciTech Connect

    Griffith, R.L. Jr.

    1994-07-01

    The Department of Energy Transportation Management Division has developed training module 14, entitled {open_quotes}Transportation of Explosives{close_quotes} to compliment the basic {open_quotes}core ten{close_quotes} training modules of the Hazardous Materials Modular Training Program. The purpose of this training module is to increase awareness of the Department of Transportation (DOT) requirements concerning the packaging and transportation of explosives. Topics covered in module 14 include the classification of explosives, approval and registration of explosives, packaging requirements, hazard communication requirements, separation and segregation compatibility requirements, loading and unloading operations, as well as safety measures required in the event of a vehicle accident involving explosives.

  5. Tunnel magnetoresistance and linear conductance of double quantum dots strongly coupled to ferromagnetic leads

    SciTech Connect

    Weymann, Ireneusz

    2015-05-07

    We analyze the spin-dependent linear-response transport properties of double quantum dots strongly coupled to external ferromagnetic leads. By using the numerical renormalization group method, we determine the dependence of the linear conductance and tunnel magnetoresistance on the degree of spin polarization of the leads and the position of the double dot levels. We focus on the transport regime where the system exhibits the SU(4) Kondo effect. It is shown that the presence of ferromagnets generally leads the suppression of the linear conductance due to the presence of an exchange field. Moreover, the exchange field gives rise to a transition from the SU(4) to the orbital SU(2) Kondo effect. We also analyze the dependence of the tunnel magnetoresistance on the double dot levels' positions and show that it exhibits a very nontrivial behavior.

  6. DOE and the Department of Transportation Announce Collaboration to Support

    Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)

    Smart Transportation Systems and Alternative Fuel Technologies | Department of Energy the Department of Transportation Announce Collaboration to Support Smart Transportation Systems and Alternative Fuel Technologies DOE and the Department of Transportation Announce Collaboration to Support Smart Transportation Systems and Alternative Fuel Technologies April 29, 2016 - 4:00pm Addthis The U.S. Department of Energy (DOE) and the U.S. Department of Transportation (DOT) announced a collaboration

  7. Final Progress Report for Project Entitled: Quantum Dot Tracers for Use in Engineered Geothermal Systems

    SciTech Connect

    Rose, Peter; Bartl, Michael; Reimus, Paul; Williams, Mark; Mella, Mike

    2015-09-12

    The objective of this project was to develop and demonstrate a new class of tracers that offer great promise for use in characterizing fracture networks in EGS reservoirs. From laboratory synthesis and testing through numerical modeling and field demonstrations, we have demonstrated the amazing versatility and applicability of quantum dot tracers. This report summarizes the results of four years of research into the design, synthesis, and characterization of semiconductor nanocrystals (quantum dots) for use as geothermal tracers.

  8. Quantitative multiplexed quantum dot immunohistochemistry

    SciTech Connect

    Sweeney, E.; Ward, T.H.; Gray, N.; Womack, C.; Jayson, G.; Hughes, A.; Dive, C.; Byers, R.

    2008-09-19

    Quantum dots are photostable fluorescent semiconductor nanocrystals possessing wide excitation and bright narrow, symmetrical, emission spectra. These characteristics have engendered considerable interest in their application in multiplex immunohistochemistry for biomarker quantification and co-localisation in clinical samples. Robust quantitation allows biomarker validation, and there is growing need for multiplex staining due to limited quantity of clinical samples. Most reported multiplexed quantum dot staining used sequential methods that are laborious and impractical in a high-throughput setting. Problems associated with sequential multiplex staining have been investigated and a method developed using QDs conjugated to biotinylated primary antibodies, enabling simultaneous multiplex staining with three antibodies. CD34, Cytokeratin 18 and cleaved Caspase 3 were triplexed in tonsillar tissue using an 8 h protocol, each localised to separate cellular compartments. This demonstrates utility of the method for biomarker measurement enabling rapid measurement of multiple co-localised biomarkers on single paraffin tissue sections, of importance for clinical trial studies.

  9. Quantum Dot Light Emitting Diode

    SciTech Connect

    Keith Kahen

    2008-07-31

    The project objective is to create low cost coatable inorganic light emitting diodes, composed of quantum dot emitters and inorganic nanoparticles, which have the potential for efficiencies equivalent to that of LEDs and OLEDs and lifetime, brightness, and environmental stability between that of LEDs and OLEDs. At the end of the project the Recipient shall gain an understanding of the device physics and properties of Quantum-Dot LEDs (QD-LEDs), have reliable and accurate nanocrystal synthesis routines, and have formed green-yellow emitting QD-LEDs with a device efficiency greater than 3 lumens/W, a brightness greater than 400 cd/m2, and a device operational lifetime of more than 1000 hours. Thus the aim of the project is to break the current cost-efficiency paradigm by creating novel low cost inorganic LEDs composed of inorganic nanoparticles.

  10. Quantum Dot Light Emitting Diode

    SciTech Connect

    Kahen, Keith

    2008-07-31

    The project objective is to create low cost coatable inorganic light emitting diodes, composed of quantum dot emitters and inorganic nanoparticles, which have the potential for efficiencies equivalent to that of LEDs and OLEDs and lifetime, brightness, and environmental stability between that of LEDs and OLEDs. At the end of the project the Recipient shall gain an understanding of the device physics and properties of Quantum-Dot LEDs (QD-LEDs), have reliable and accurate nanocrystal synthesis routines, and have formed green-yellow emitting QD-LEDs with a device efficiency greater than 3 lumens/W, a brightness greater than 400 cd/m{sup 2}, and a device operational lifetime of more than 1000 hours. Thus the aim of the project is to break the current cost-efficiency paradigm by creating novel low cost inorganic LEDs composed of inorganic nanoparticles.

  11. Transportation Secure Data Center: Real-World Data for Planning, Modeling and Analysis (Fact Sheet)

    SciTech Connect

    Not Available

    2013-01-01

    The National Renewable Energy Laboratory (NREL) and the U.S. Department of Transportation (DOT) have launched the free, web-based Transportation Secure Data Center (TSDC). The TSDC (www.nrel.gov/tsdc) preserves respondent anonymity while making vital transportation data available to a broad group of users through secure, online access. The TSDC database gives, metropolitan planning organizations, universities, national laboratories, air quality management districts, disaster planning agencies and auto manufacturers free-of-charge web-based access to valuable transportation data. The TSDC's two levels of access make composite data available with simple online registration, and allow researchers to use detailed spatial data after completing a straight forward application process.

  12. Investigation of Quantum Dot?Quantum Dot Coupling at High Hydrostatic

    Office of Scientific and Technical Information (OSTI)

    Pressure. (Conference) | SciTech Connect Investigation of Quantum Dot?Quantum Dot Coupling at High Hydrostatic Pressure. Citation Details In-Document Search Title: Investigation of Quantum Dot?Quantum Dot Coupling at High Hydrostatic Pressure. Abstract not provided. Authors: Brener, Igal ; Liu, Sheng ; Fan, Hongyou ; Luk, Ting S. ; Li, Binsong ; Prasankumar, Rohit ; Sinclair, Michael B. Publication Date: 2014-09-01 OSTI Identifier: 1241660 Report Number(s): SAND2014-17977C 537696 DOE

  13. Controlling thermal conductance through quantum dot roughening...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: Controlling thermal conductance through quantum dot roughening at interfaces. Citation Details ... Publication Date: 2011-01-01 OSTI Identifier: 1110382 Report ...

  14. Semiconductor nanocrystal quantum dot synthesis approaches towards...

    Office of Scientific and Technical Information (OSTI)

    In addition, applications that demand to utilize quantum dots as "commodity" chemicals are discussed, including solar cells and solid-state lightings. Authors: Hu, Michael Z. 1 ; ...

  15. The dosimetric consequences of the new DOT LSA definition

    SciTech Connect

    Mis, F.J.

    1996-10-01

    As a result of the new regulations for the transportation of radioactive materials, the DOT and the NRC have implemented a rule designed to limit the activity in an LSA container. This is a new regulation designed to insure that the spirit of the law as well as the letter of the law are followed for LSA shipments. Specifically, it limits the dose rate at any location on an unshielded LSA container to less than 1 rem/hr at 3 meters. Other possible alternatives had been discussed prior to the implementation of this regulation including multiples of A{sub 2} values, as implemented by the French.

  16. A comparison between semi-spheroid- and dome-shaped quantum dots coupled to wetting layer

    SciTech Connect

    Shahzadeh, Mohammadreza; Sabaeian, Mohammad

    2014-06-15

    During the epitaxial growth method, self-assembled semi-spheroid-shaped quantum dots (QDs) are formed on the wetting layer (WL). However for sake of simplicity, researchers sometimes assume semi-spheroid-shaped QDs to be dome-shaped (hemisphere). In this work, a detailed and comprehensive study on the difference between electronic and transition properties of dome- and semi-spheroid-shaped quantum dots is presented. We will explain why the P-to-S intersubband transition behaves the way it does. The calculated results for intersubband P-to-S transition properties of quantum dots show two different trends for dome-shaped and semi-spheroid-shaped quantum dots. The results are interpreted using the probability of finding electron inside the dome/spheroid region, with emphasis on the effects of wetting layer. It is shown that dome-shaped and semi-spheroid-shaped quantum dots feature different electronic and transition properties, arising from the difference in lateral dimensions between dome- and semi-spheroid-shaped QDs. Moreover, an analogy is presented between the bound S-states in the quantum dots and a simple 3D quantum mechanical particle in a box, and effective sizes are calculated. The results of this work will benefit researchers to present more realistic models of coupled QD/WL systems and explain their properties more precisely.

  17. Generation of even harmonics in coupled quantum dots (Journal...

    Office of Scientific and Technical Information (OSTI)

    Generation of even harmonics in coupled quantum dots Citation Details In-Document Search Title: Generation of even harmonics in coupled quantum dots Using the spatial-temporal...

  18. DOE Science Showcase - Quantum Dots | OSTI, US Dept of Energy...

    Office of Scientific and Technical Information (OSTI)

    For additional information, see the OSTI Catalogue of Collections. RefreshLine.png Additional Resources Quantum dot, Wikipedia Quantum dot solar cell, Wikipedia Los Alamos Quantum ...

  19. Quantum Dots Promise to Significantly Boost Solar Cell Efficiencies...

    Office of Scientific and Technical Information (OSTI)

    Quantum Dots Promise to Significantly Boost Solar Cell Efficiencies (Fact Sheet) Citation Details In-Document Search Title: Quantum Dots Promise to Significantly Boost Solar Cell ...

  20. Mastermind Session: Connecting the Dots Between the Real Estate...

    Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)

    Connecting the Dots Between the Real Estate Market and Residential Energy Efficiency Mastermind Session: Connecting the Dots Between the Real Estate Market and Residential Energy ...

  1. Test and evaluation document for DOT Specification 7A Type A Packaging. Revision 3

    SciTech Connect

    1996-01-30

    The US Department of Energy (DOE) has been conducting, through several of its operating contractors, an evaluation and testing program to qualify Type A radioactive material packagings per US Department of Transportation (DOT) Specification 7A (DOT-7A) of the Code of Federal Regulations (CFR), Title 49, Part 178 (49 CFR 178). The program is currently administered by the DOE, Office of Facility Safety Analysis, DOE/EH-32, at DOE-Headquarters (DOE-HQ) in Germantown, Maryland. This document summarizes the evaluation and testing performed for all of the packagings successfully qualified in this program.

  2. HMPT: Hazardous Waste Transportation Live 27928, Test 27929 (Technical

    Office of Scientific and Technical Information (OSTI)

    Report) | SciTech Connect HMPT: Hazardous Waste Transportation Live 27928, Test 27929 Citation Details In-Document Search Title: HMPT: Hazardous Waste Transportation Live 27928, Test 27929 HMPT: Hazardous Waste Transportation (Live 27928, suggested one time and associated Test 27929, required initially and every 36 months) addresses the Department of Transportation (DOT) function-specific training requirements of the hazardous materials packagings and transportation (HMPT) Los Alamos

  3. Research and development of proton-exchange membrane (PEM) fuel cell system for transportation applications. Phase I final report

    SciTech Connect

    1996-01-01

    Objective during Phase I was to develop a methanol-fueled 10-kW fuel cell power source and evaluate its feasibility for transportation applications. This report documents research on component (fuel cell stack, fuel processor, power source ancillaries and system sensors) development and the 10-kW power source system integration and test. The conceptual design study for a PEM fuel cell powered vehicle was documented in an earlier report (DOE/CH/10435-01) and is summarized herein. Major achievements in the program include development of advanced membrane and thin-film low Pt-loaded electrode assemblies that in reference cell testing with reformate-air reactants yielded performance exceeding the program target (0.7 V at 1000 amps/ft{sup 2}); identification of oxidation catalysts and operating conditions that routinely result in very low CO levels ({le} 10 ppm) in the fuel processor reformate, thus avoiding degradation of the fuel cell stack performance; and successful integrated operation of a 10-kW fuel cell stack on reformate from the fuel processor.

  4. Single-dot optical emission from ultralow density well-isolated InP quantum dots

    SciTech Connect

    Ugur, A.; Hatami, F.; Masselink, W. T.; Vamivakas, A. N.; Lombez, L.; Atatuere, M.

    2008-10-06

    We demonstrate a straightforward way to obtain single well-isolated quantum dots emitting in the visible part of the spectrum and characterize the optical emission from single quantum dots using this method. Self-assembled InP quantum dots are grown using gas-source molecular-beam epitaxy over a wide range of InP deposition rates, using an ultralow growth rate of about 0.01 atomic monolayers/s, a quantum-dot density of 1 dot/{mu}m{sup 2} is realized. The resulting isolated InP quantum dots embedded in an InGaP matrix are individually characterized without the need for lithographical patterning and masks on the substrate. Such low-density quantum dots show excitonic emission at around 670 nm with a linewidth limited by instrument resolution. This system is applicable as a single-photon source for applications such as quantum cryptography.

  5. Research Challenge 5: Enhanced Spontaneous Emission

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    ... dielectric structures and assemblies of emitters (2D photonic crystals and quantum dots, QDs). research-challenge-5-enhanced-spontaneous-emission-5001 (a) Coreshell ...

  6. Thick-shell nanocrystal quantum dots

    SciTech Connect

    Hollingsworth, Jennifer A.; Chen, Yongfen; Klimov, Victor I.; Htoon, Han; Vela, Javier

    2011-05-03

    Colloidal nanocrystal quantum dots comprising an inner core having an average diameter of at least 1.5 nm and an outer shell, where said outer shell comprises multiple monolayers, wherein at least 30% of the quantum dots have an on-time fraction of 0.80 or greater under continuous excitation conditions for a period of time of at least 10 minutes.

  7. Photoluminescence of a quantum-dot molecule

    SciTech Connect

    Kruchinin, Stanislav Yu.; Rukhlenko, Ivan D.; Baimuratov, Anvar S.; Leonov, Mikhail Yu.; Turkov, Vadim K.; Baranov, Alexander V.; Fedorov, Anatoly V.; Gun'ko, Yurii K.

    2015-01-07

    The coherent coupling of quantum dots is a sensitive indicator of the energy and phase relaxation processes taking place in the nanostructure components. We formulate a theory of low-temperature, stationary photoluminescence from a quantum-dot molecule composed of two spherical quantum dots whose electronic subsystems are resonantly coupled via the Coulomb interaction. We show that the coupling leads to the hybridization of the first excited states of the quantum dots, manifesting itself as a pair of photoluminescence peaks with intensities and spectral positions strongly dependent on the geometric, material, and relaxation parameters of the quantum-dot molecule. These parameters are explicitly contained in the analytical expression for the photoluminescence differential cross section derived in the paper. The developed theory and expression obtained are essential in interpreting and analyzing spectroscopic data on the secondary emission of coherently coupled quantum systems.

  8. Theory Of Alkyl Terminated Silicon Quantum Dots

    SciTech Connect

    Reboredo, F; Galli, G

    2004-08-19

    We have carried out a series of ab-initio calculations to investigate changes in the optical properties of Si quantum dots as a function of surface passivation. In particular, we have compared hydrogen passivated dots with those having alkyl groups at the surface. We find that, while on clusters with reconstructed surfaces a complete alkyl passivation is possible, steric repulsion prevents full passivation of Si dots with unreconstructed surfaces. In addition, our calculations show that steric repulsion may have a dominant effect in determining the surface structure, and eventually the stability of alkyl passivated clusters, with results dependent on the length of the carbon chain. Alkyl passivation weakly affects optical gaps of silicon quantum dots, while it substantially decreases ionization potentials and electron affinities and affect their excited state properties. On the basis of our results we propose that alkyl terminated quantum dots may be size selected taking advantage of the change in ionization potential as a function of the cluster size.

  9. Regional Transportation Simulation Tool for Emergency Planning

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    rtstep-diag TRACC RESEARCH Computational Fluid Dynamics Computational Structural Mechanics Transportation Systems Modeling Regional Transportation Simulation Tool for Emergency ...

  10. Sustainable Transportation - Continuum Magazine | NREL

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    A Closer Look Slideshow: Sustainable Transportation NREL research, development, and ... Continuum Sustainable Transportation Fall 2013 Issue 5 Download the print version. RSS ...

  11. Transport Measurements in Silicon Quantum Dots with Counted Antimony...

    Office of Scientific and Technical Information (OSTI)

    DOE Contract Number: AC04-94AL85000 Resource Type: Conference Resource Relation: Conference: Proposed for presentation at the Quantum Computing Program Review held August 10-12, ...

  12. Semiconductor Nanocrystal Quantum Dot Synthesis Approaches Towards...

    Office of Scientific and Technical Information (OSTI)

    Large-Scale Industrial Production for Energy Applications CrossMark Michael Z. Hu* and ... The large quantity demands of high-quality quantum dots for advanced energy applications ...

  13. Electron Spin Dynamics in Semiconductor Quantum Dots

    SciTech Connect

    Marie, X.; Belhadj, T.; Urbaszek, B.; Amand, T.; Krebs, O.; Lemaitre, A.; Voisin, P.

    2011-07-15

    An electron spin confined to a semiconductor quantum dot is not subject to the classical spin relaxation mechanisms known for free carriers but it strongly interacts with the nuclear spin system via the hyperfine interaction. We show in time resolved photoluminescence spectroscopy experiments on ensembles of self assembled InAs quantum dots in GaAs that this interaction leads to strong electron spin dephasing.

  14. First principle thousand atom quantum dot calculations

    SciTech Connect

    Wang, Lin-Wang; Li, Jingbo

    2004-03-30

    A charge patching method and an idealized surface passivation are used to calculate the single electronic states of IV-IV, III-V, II-VI semiconductor quantum dots up to a thousand atoms. This approach scales linearly and has a 1000 fold speed-up compared to direct first principle methods with a cost of eigen energy error of about 20 meV. The calculated quantum dot band gaps are parametrized for future references.

  15. Investigation of size dependent structural and optical properties of thin films of CdSe quantum dots

    SciTech Connect

    Sharma, Madhulika; Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology, Bombay, Powai, Mumbai 400076 ; Sharma, A.B.; Mishra, N.; Pandey, R.K.

    2011-03-15

    Research highlights: {yields} CdSe q-dots have been synthesized using simple chemical synthesis route. {yields} Thin film of CdSe quantum dots exhibited self-organized growth. {yields} Size dependent blue shift observed in the absorption edge of CdSe nanocrystallites. {yields} PL emission band corresponds to band edge luminescence and defect luminescence. {yields} Organized growth led to enhancement in luminescence yield of smaller size Q-dots. -- Abstract: Cadmium selenide (CdSe) quantum dots were grown on indium tin oxide substrate using wet chemical technique for possible application as light emitting devices. The structural, morphological and luminescence properties of the as deposited thin films of CdSe Q-dot have been investigated, using X-ray diffraction, transmission electron microscopy, atomic force microscopy and optical and luminescence spectroscopy. The quantum dots have been shown to deposit in an organized array on ITO/glass substrate. The as grown Q-dots exhibited size dependent blue shift in the absorption edge. The effect of quantum confinement also manifested as a blue shift of photoluminescence emission. It is shown that the nanocrystalline CdSe exhibits intense photoluminescence as compared to the large grained polycrystalline CdSe films.

  16. Approaches to Future Generation Photovoltaics and Solar Fuels: Quantum Dots, Arrays, and Quantum Dot Solar Cells

    SciTech Connect

    Semonin, O.; Luther, J.; Beard, M.; Johnson, J.; Gao, J.; Nozik, A.

    2012-01-01

    One potential, long-term approach to more efficient and lower cost future generation solar cells for solar electricity and solar fuels is to utilize the unique properties of quantum dots (QDs) to control the relaxation pathways of excited states to enhance multiple exciton generation (MEG). We have studied MEG in close-packed PbSe QD arrays where the QDs are electronically coupled in the films and thus exhibit good transport while still maintaining quantization and MEG. We have developed simple, all-inorganic solution-processable QD solar cells that produce large short-circuit photocurrents and power conversion efficiencies above 5% via nanocrystalline p-n junctions. These solar cells show QYs for photocurrent that exceed 100% in the photon energy regions where MEG is possible; the photocurrent MEG QYs as a function of photon energy match those determined via time-resolved spectroscopy Recent analyses of the major effect of MEG combined with solar concentration on the conversion efficiency of solar cells will also be discussed.

  17. Transportation Energy Consortiums

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    ... Physics of hydrogen in materials - Our research develops an understanding of reactions on surfaces, hydrogen transport in materials, embrittlement mechanisms, deformation and ...

  18. Tungsten impurity transport experiments in Alcator C-Mod to address high priority research and development for ITER

    SciTech Connect

    Loarte, A.; Polevoi, A. R.; Hosokawa, M.; Reinke, M. L.; Chilenski, M.; Howard, N.; Hubbard, A.; Hughes, J. W.; Rice, J. E.; Walk, J.; Köchl, F.; Pütterich, T.; Dux, R.; Zhogolev, V. E.

    2015-05-15

    Experiments in Alcator C-Mod tokamak plasmas in the Enhanced D-alpha H-mode regime with ITER-like mid-radius plasma density peaking and Ion Cyclotron Resonant heating, in which tungsten is introduced by the laser blow-off technique, have demonstrated that accumulation of tungsten in the central region of the plasma does not take place in these conditions. The measurements obtained are consistent with anomalous transport dominating tungsten transport except in the central region of the plasma where tungsten transport is neoclassical, as previously observed in other devices with dominant neutral beam injection heating, such as JET and ASDEX Upgrade. In contrast to such results, however, the measured scale lengths for plasma temperature and density in the central region of these Alcator C-Mod plasmas, with density profiles relatively flat in the core region due to the lack of core fuelling, are favourable to prevent inter and intra sawtooth tungsten accumulation in this region under dominance of neoclassical transport. Simulations of ITER H-mode plasmas, including both anomalous (modelled by the Gyro-Landau-Fluid code GLF23) and neoclassical transport for main ions and tungsten and with density profiles of similar peaking to those obtained in Alcator C-Mod show that accumulation of tungsten in the central plasma region is also unlikely to occur in stationary ITER H-mode plasmas due to the low fuelling source by the neutral beam injection (injection energy ∼ 1 MeV), which is in good agreement with findings in the Alcator C-Mod experiments.

  19. Energy Department Welcomes Department of Transportation as New Workplace Charging Challenge Partner

    Energy.gov [DOE]

    Today, the Energy Department is welcoming the Department of Transportation (DOT) as a partner in its Workplace Charging Challenge, which aims to make workplace charging for plug-in electric vehicles available to employees across the country.

  20. Research Highlights

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    ADCLES » Chemistry » Research Highlights Research Highlights A publication highlights recent advances. Contact Us Division Leader David Morris Deputy Division Leader Mark McCleskey (505) 667-4457 Division Office (505) 667-4457 Email Extraordinary work from Chemistry Division staff 2016 Nuclear Forensics Undergraduate Summer School 2017 11/15 Quantum Dot Solar Windows Technology Wins Special R&D 100 Award Recognition 11/15 Los Alamos scientist recognized for work to increase availability of

  1. (In,Mn)As multilayer quantum dot structures

    SciTech Connect

    Bouravleuv, Alexei; Sapega, Victor; Nevedomskii, Vladimir; Khrebtov, Artem; Samsonenko, Yuriy; Cirlin, George

    2014-12-08

    (In,Mn)As multilayer quantum dots structures were grown by molecular beam epitaxy using a Mn selective doping of the central parts of quantum dots. The study of the structural and magneto-optical properties of the samples with three and five layers of (In,Mn)As quantum dots has shown that during the quantum dots assembly, the out-diffusion of Mn from the layers with (In,Mn)As quantum dots can occur resulting in the formation of the extended defects. To produce a high quality structures using the elaborated technique of selective doping, the number of (In,Mn)As quantum dot layers should not exceed three.

  2. OSTIblog Articles in the quantum dots Topic | OSTI, US Dept of Energy

    Office of Scientific and Technical Information (OSTI)

    Office of Scientific and Technical Information dots

  3. The Fluid Interface Reactions Structures and Transport (FIRST) EFRC (A "Life at the Frontiers of Energy Research" contest entry from the 2011 Energy Frontier Research Centers (EFRCs) Summit and Forum)

    ScienceCinema

    Wesolowski, David J. (Director, FIRST - Fluid Interface Reactions, Structures, and Transport Center); FIRST Staff

    2016-07-12

    'The Fluid Interface Reactions Structures and Transport (FIRST) EFRC' was submitted by FIRST to the 'Life at the Frontiers of Energy Research' video contest at the 2011 Science for Our Nation's Energy Future: Energy Frontier Research Centers (EFRCs) Summit and Forum. Twenty-six EFRCs created short videos to highlight their mission and their work. FIRST, an EFRC directed by David J. Wesolowski at the Oak Ridge National Laboratory is a partnership of scientists from nine institutions: Oak Ridge National Laboratory (lead), Argonne National Laboratory, Drexel University, Georgia State University, Northwestern University, Pennsylvania State University, Suffolk University, Vanderbilt University, and University of Virginia. The Office of Basic Energy Sciences in the U.S. Department of Energy's Office of Science established the 46 Energy Frontier Research Centers (EFRCs) in 2009. These collaboratively-organized centers conduct fundamental research focused on 'grand challenges' and use-inspired 'basic research needs' recently identified in major strategic planning efforts by the scientific community. The overall purpose is to accelerate scientific progress toward meeting the nation's critical energy challenges. The mission of Fluid Interface Reactions, Structures and Transport Center is 'to develop quantitative and predictive models of the unique nanoscale environment at fluid-solid interfaces that will enable transformational advances in electrical energy storage and heterogeneous catalysis for solar fuels.' Research topics are: catalysis (biomass, CO{sub 2}, water), electrocatalysis, photocatalysis, photoelectrocatalysis, solar fuels, solar electrodes, electrical energy storage, batteries, capacitors, battery electrodes, electrolytes, extreme environment, CO{sub 2} (convert), greenhouse gas, microelectromechanical systems (MEMS), interfacial characterization, matter by design, novel materials synthesis, and charge transport.

  4. The Fluid Interface Reactions Structures and Transport (FIRST) EFRC (A "Life at the Frontiers of Energy Research" contest entry from the 2011 Energy Frontier Research Centers (EFRCs) Summit and Forum)

    SciTech Connect

    Wesolowski, David J.; FIRST Staff

    2011-05-01

    'The Fluid Interface Reactions Structures and Transport (FIRST) EFRC' was submitted by FIRST to the 'Life at the Frontiers of Energy Research' video contest at the 2011 Science for Our Nation's Energy Future: Energy Frontier Research Centers (EFRCs) Summit and Forum. Twenty-six EFRCs created short videos to highlight their mission and their work. FIRST, an EFRC directed by David J. Wesolowski at the Oak Ridge National Laboratory is a partnership of scientists from nine institutions: Oak Ridge National Laboratory (lead), Argonne National Laboratory, Drexel University, Georgia State University, Northwestern University, Pennsylvania State University, Suffolk University, Vanderbilt University, and University of Virginia. The Office of Basic Energy Sciences in the U.S. Department of Energy's Office of Science established the 46 Energy Frontier Research Centers (EFRCs) in 2009. These collaboratively-organized centers conduct fundamental research focused on 'grand challenges' and use-inspired 'basic research needs' recently identified in major strategic planning efforts by the scientific community. The overall purpose is to accelerate scientific progress toward meeting the nation's critical energy challenges. The mission of Fluid Interface Reactions, Structures and Transport Center is 'to develop quantitative and predictive models of the unique nanoscale environment at fluid-solid interfaces that will enable transformational advances in electrical energy storage and heterogeneous catalysis for solar fuels.' Research topics are: catalysis (biomass, CO{sub 2}, water), electrocatalysis, photocatalysis, photoelectrocatalysis, solar fuels, solar electrodes, electrical energy storage, batteries, capacitors, battery electrodes, electrolytes, extreme environment, CO{sub 2} (convert), greenhouse gas, microelectromechanical systems (MEMS), interfacial characterization, matter by design, novel materials synthesis, and charge transport.

  5. Carrier multiplication detected through transient photocurrent in device-grade films of lead selenide quantum dots

    SciTech Connect

    Gao, Jianbo; Fidler, Andrew F.; Klimov, Victor I.

    2015-09-08

    In carrier multiplication, the absorption of a single photon results in two or more electron–hole pairs. Quantum dots are promising materials for implementing carrier multiplication principles in real-life technologies. So far, however, most of research in this area has focused on optical studies of solution samples with yet to be proven relevance to practical devices. We report ultra-fast electro-optical studies of device-grade films of electronically coupled quantum dots that allow us to observe multiplication directly in the photocurrent. Our studies help rationalize previous results from both optical spectroscopy and steady-state photocurrent measurements and also provide new insights into effects of electric field and ligand treatments on multiexciton yields. Importantly, we demonstrate that using appropriate chemical treatments of the films, extra charges produced by carrier multiplication can be extracted from the quantum dots before they are lost to Auger recombination and hence can contribute to photocurrent of practical devices.

  6. Next-Generation "Giant" Quantum Dots: Performance-Engineered...

    Energy.gov [DOE] (indexed site)

    This project seeks to develop quantum-dot downconverters to be used in LED lighting. The focus will be on synthesizing red-emitting quantum dots, revealing their failure ...

  7. Surface treatment of nanocrystal quantum dots after film deposition

    DOEpatents

    Sykora, Milan; Koposov, Alexey; Fuke, Nobuhiro

    2015-02-03

    Provided are methods of surface treatment of nanocrystal quantum dots after film deposition so as to exchange the native ligands of the quantum dots for exchange ligands that result in improvement in charge extraction from the nanocrystals.

  8. US Department of Transportation specification packages evaluation

    SciTech Connect

    Ratledge, J.E.; Rawl, R.R.

    1992-01-01

    Specification packages are broad families of package designs and approved by the Department of Transportation (DOT) for transport of certain classes of radioactive materials, with each specification containing a number of designs of various sizes. Many of the individual package designs are not supported by reasonably current safety analyses. The Nuclear Regulatory Commission (NRC) asked Oak Ridge National Laboratory (ORNL) staff to collect all related information, perform analyses, and identify alternative actions that will enable NRC and DOT to make informed decisions on whether to retain, withdraw, or modify the existing regulatory permission for the use of specification packages to transport radioactive and fissile materials. This paper presents the background, issues, and progress made in this activity.

  9. US Department of Transportation specification packages evaluation

    SciTech Connect

    Ratledge, J.E.; Rawl, R.R.

    1992-03-01

    Specification packages are broad families of package designs and approved by the Department of Transportation (DOT) for transport of certain classes of radioactive materials, with each specification containing a number of designs of various sizes. Many of the individual package designs are not supported by reasonably current safety analyses. The Nuclear Regulatory Commission (NRC) asked Oak Ridge National Laboratory (ORNL) staff to collect all related information, perform analyses, and identify alternative actions that will enable NRC and DOT to make informed decisions on whether to retain, withdraw, or modify the existing regulatory permission for the use of specification packages to transport radioactive and fissile materials. This paper presents the background, issues, and progress made in this activity.

  10. The effect of Coulomb interactions on nonlinear thermovoltage and thermocurrent in quantum dots

    SciTech Connect

    Zimbovskaya, Natalya A.

    2015-06-28

    In the present work, we theoretically study the nonlinear regime of charge transport through a quantum dot coupled to the source and drain reservoirs. The investigation is carried out using a nonequilibrium Green’s function formalism beyond the Hartree-Fock approximation. Employed approximations for the relevant Green’s functions allow to trace a transition from Coulomb blockade regime to Kondo regime in the thermoelectric transport. Effects arising when electrons move in response to thermal gradient applied across the system are discussed, including experimentally observed thermovoltage zeros.

  11. Research and Development of Proton-Exchange Membrane (PEM) Fuel Cell System for Transportation Applications: Initial Conceptual Design Report

    SciTech Connect

    Not Available

    1993-11-30

    This report addresses Task 1.1, model development and application, and Task 1.2, vehicle mission definition. Overall intent is to produce a methanol-fueled 10-kW power source, and to evaluate electrochemical engine (ECE) use in transportation. Major achievements include development of an ECE power source model and its integration into a comprehensive power source/electric vehicle propulsion model, establishment of candidate FCV (fuel cell powered electric vehicle) mission requirements, initial FCV studies, and a candidate FCV recommendation for further study.

  12. Surface treatment of nanocrystal quantum dots after film deposition

    Office of Scientific and Technical Information (OSTI)

    (Patent) | SciTech Connect Patent: Surface treatment of nanocrystal quantum dots after film deposition Citation Details In-Document Search Title: Surface treatment of nanocrystal quantum dots after film deposition Provided are methods of surface treatment of nanocrystal quantum dots after film deposition so as to exchange the native ligands of the quantum dots for exchange ligands that result in improvement in charge extraction from the nanocrystals. Authors: Sykora, Milan ; Koposov, Alexey

  13. Quantum Dot-Based Cell Motility Assay

    SciTech Connect

    Gu, Weiwei; Pellegrino, Teresa; Parak Wolfgang J; Boudreau,Rosanne; Le Gros, Mark A.; Gerion, Daniele; Alivisatos, A. Paul; Larabell, Carolyn A.

    2005-06-06

    Because of their favorable physical and photochemical properties, colloidal CdSe/ZnS-semiconductor nanocrystals (commonly known as quantum dots) have enormous potential for use in biological imaging. In this report, we present an assay that uses quantum dots as markers to quantify cell motility. Cells that are seeded onto a homogeneous layer of quantum dots engulf and absorb the nanocrystals and, as a consequence, leave behind a fluorescence-free trail. By subsequently determining the ratio of cell area to fluorescence-free track area, we show that it is possible to differentiate between invasive and noninvasive cancer cells. Because this assay uses simple fluorescence detection, requires no significant data processing, and can be used in live-cell studies, it has the potential to be a powerful new tool for discriminating between invasive and noninvasive cancer cell lines or for studying cell signaling events involved in migration.

  14. Exciton binding energy in semiconductor quantum dots

    SciTech Connect

    Pokutnii, S. I.

    2010-04-15

    In the adiabatic approximation in the context of the modified effective mass approach, in which the reduced exciton effective mass {mu} = {mu}(a) is a function of the radius a of the semiconductor quantum dot, an expression for the exciton binding energy E{sub ex}(a) in the quantum dot is derived. It is found that, in the CdSe and CdS quantum dots with the radii a comparable to the Bohr exciton radii a{sub ex}, the exciton binding energy E{sub ex}(a) is substantially (respectively, 7.4 and 4.5 times) higher than the exciton binding energy in the CdSe and CdS single crystals.

  15. NREL: Transportation Research - Archives for the Transportation...

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    - Marketplace Impact October 2014 - Reliability, Durability, and Safety July 2014 - Big Data, Models & Tools May 2014 - Medium- and Heavy-Duty Vehicles March 2014 - NREL in the ...

  16. NREL: Transportation Research - Transportation and Hydrogen Newsletter...

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    partners, including original equipment manufacturers, suppliers, fleets, national labs, Clean Cities coalitions, the Energy Department, the Federal Highway Administration, the...

  17. NREL: Transportation Research - Transportation Secure Data Center

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    NREL processing routines join data points to the road network, link U.S. Census and other spatial data layers, and add information such as road grade. Cleansed Data Access Users ...

  18. Bilayer graphene quantum dot defined by topgates

    SciTech Connect

    Müller, André; Kaestner, Bernd; Hohls, Frank; Weimann, Thomas; Pierz, Klaus; Schumacher, Hans W.

    2014-06-21

    We investigate the application of nanoscale topgates on exfoliated bilayer graphene to define quantum dot devices. At temperatures below 500 mK, the conductance underneath the grounded gates is suppressed, which we attribute to nearest neighbour hopping and strain-induced piezoelectric fields. The gate-layout can thus be used to define resistive regions by tuning into the corresponding temperature range. We use this method to define a quantum dot structure in bilayer graphene showing Coulomb blockade oscillations consistent with the gate layout.

  19. TEST & EVALUATION REPORT FOR THE HEDGEHOG-II PACKAGING SYSTEMS DOT-7A TYPE A CONTAINER

    SciTech Connect

    KELLY, D.L.

    2003-12-29

    This report documents the US. Department of Transportation Specification 7A (DOT-7A) Type A compliance test and evaluation results for the Hedgehog-II packaging systems. The approved Hedgehog-II packaging configurations provide primary and secondary containment. The approved packaging configurations described within this report are designed to ship Type A quantities of radioactive materials, normal form. Contents may be in solid or liquid form. Liquids transported in the approved 1 L glass bottle assembly shall have a specific gravity of less than or equal to 1.6. Liquids transported in all other approved configurations shall have a specific gravity of less than or equal to 2.0. The solid contents, including packaging, are limited in weight to the gross weight of the as-tested liquids and bottles. The approved Hedgehog-II packaging configurations described in this report may be transported by air, and have been evaluated as meeting the applicable International Air Transport Association/International Civil Aviation Organization (IATA/ICAO) Dangerous Goods Regulations in addition to the DOT requirements.

  20. Kondo and mixed-valence regimes in multilevel quantum dots

    SciTech Connect

    Chudnovskiy, A. L.; Ulloa, S. E.

    2001-04-15

    We investigate the dependence of the ground state of a multilevel quantum dot on the coupling to an external fermionic system and on the interactions in the dot. As the coupling to the external system increases, the rearrangement of the effective energy levels in the dot signals the transition from the Kondo regime to a mixed-valence (MV) regime. The MV regime in a two-level dot is characterized by an intrinsic mixing of the levels in the dot, resulting in nonperturbative subtunneling and supertunneling phenomena that strongly influence the Kondo effect.

  1. Synthesis of CdSe quantum dots for quantum dot sensitized solar cell

    SciTech Connect

    Singh, Neetu Kapoor, Avinashi; Kumar, Vinod; Mehra, R. M.

    2014-04-24

    CdSe Quantum Dots (QDs) of size 0.85 nm were synthesized using chemical route. ZnO based Quantum Dot Sensitized Solar Cell (QDSSC) was fabricated using CdSe QDs as sensitizer. The Pre-synthesized QDs were found to be successfully adsorbed on front ZnO electrode and had potential to replace organic dyes in Dye Sensitized Solar Cells (DSSCs). The efficiency of QDSSC was obtained to be 2.06 % at AM 1.5.

  2. Location deterministic biosensing from quantum-dot-nanowire assemblies

    SciTech Connect

    Liu, Chao; Kim, Kwanoh; Fan, D. L.

    2014-08-25

    Semiconductor quantum dots (QDs) with high fluorescent brightness, stability, and tunable sizes, have received considerable interest for imaging, sensing, and delivery of biomolecules. In this research, we demonstrate location deterministic biochemical detection from arrays of QD-nanowire hybrid assemblies. QDs with diameters less than 10 nm are manipulated and precisely positioned on the tips of the assembled Gold (Au) nanowires. The manipulation mechanisms are quantitatively understood as the synergetic effects of dielectrophoretic (DEP) and alternating current electroosmosis (ACEO) due to AC electric fields. The QD-nanowire hybrid sensors operate uniquely by concentrating bioanalytes to QDs on the tips of nanowires before detection, offering much enhanced efficiency and sensitivity, in addition to the position-predictable rationality. This research could result in advances in QD-based biomedical detection and inspires an innovative approach for fabricating various QD-based nanodevices.

  3. Transportation Safety Excellence in Operations Through Improved Transportation Safety Document

    SciTech Connect

    Dr. Michael A. Lehto; MAL

    2007-05-01

    A recent accomplishment of the Idaho National Laboratory (INL) Materials and Fuels Complex (MFC) Nuclear Safety analysis group was to obtain DOE-ID approval for the inter-facility transfer of greater-than-Hazard-Category-3 quantity radioactive/fissionable waste in Department of Transportation (DOT) Type A drums at MFC. This accomplishment supported excellence in operations through safety analysis by better integrating nuclear safety requirements with waste requirements in the Transportation Safety Document (TSD); reducing container and transport costs; and making facility operations more efficient. The MFC TSD governs and controls the inter-facility transfer of greater-than-Hazard-Category-3 radioactive and/or fissionable materials in non-DOT approved containers. Previously, the TSD did not include the capability to transfer payloads of greater-than-Hazard-Category-3 radioactive and/or fissionable materials using DOT Type A drums. Previous practice was to package the waste materials to less-than-Hazard-Category-3 quantities when loading DOT Type A drums for transfer out of facilities to reduce facility waste accumulations. This practice allowed operations to proceed, but resulted in drums being loaded to less than the Waste Isolation Pilot Plant (WIPP) waste acceptance criteria (WAC) waste limits, which was not cost effective or operations friendly. An improved and revised safety analysis was used to gain DOE-ID approval for adding this container configuration to the MFC TSD safety basis. In the process of obtaining approval of the revised safety basis, safety analysis practices were used effectively to directly support excellence in operations. Several factors contributed to the success of MFCs effort to obtain approval for the use of DOT Type A drums, including two practices that could help in future safety basis changes at other facilities. 1) The process of incorporating the DOT Type A drums into the TSD at MFC helped to better integrate nuclear safety

  4. Research Highlight

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Black Carbon Reduction of Snow Albedo Submitter: Kirchstetter, T. W., Lawrence Berkeley National Laboratory Area of Research: Radiation Processes Working Group(s): Aerosol Life Cycle Journal Reference: Hadley OL and TW Kirchstetter. 2012. "Black carbon reduction of snow albedo." Nature Climate Change, , doi:10.1038/nclimate1433. Spectrally weighted snow albedo over the 300-2,500 nm solar spectrum: derived from our experiments (dots, 1 standard deviation) and modelled using SNICAR

  5. Research Highlight

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Initial Aerosol Concentration Is Key Contributor to Low-Level Cloud Reflectivity Submitter: Penner, J. E., University of Michigan Area of Research: Aerosol Properties Working Group(s): Aerosol Journal Reference: Penner, J., Dong, X., Chen. Y., Observational evidence of a change in radiative forcing due to the indirect aerosol effect, Nature, Vol. 427, 15 January 2004. Cloud optical depth, as determined from the parcel model, is indicated by the dots. Red lines show best fit data of cloud liquid

  6. Inter-dot strain field effect on the optoelectronic properties of realistic InP lateral quantum-dot molecules

    SciTech Connect

    Barettin, Daniele Auf der Maur, Matthias; De Angelis, Roberta; Prosposito, Paolo; Casalboni, Mauro; Pecchia, Alessandro

    2015-03-07

    We report on numerical simulations of InP surface lateral quantum-dot molecules on In{sub 0.48}Ga{sub 0.52 }P buffer, using a model strictly derived by experimental results by extrapolation of the molecules shape from atomic force microscopy images. Our study has been inspired by the comparison of a photoluminescence spectrum of a high-density InP surface quantum dot sample with a numerical ensemble average given by a weighted sum of simulated single quantum-dot spectra. A lack of experimental optical response from the smaller dots of the sample is found to be due to strong inter-dot strain fields, which influence the optoelectronic properties of lateral quantum-dot molecules. Continuum electromechanical, k{sup →}·p{sup →} bandstructure, and optical calculations are presented for two different molecules, the first composed of two dots of nearly identical dimensions (homonuclear), the second of two dots with rather different sizes (heteronuclear). We show that in the homonuclear molecule the hydrostatic strain raises a potential barrier for the electrons in the connection zone between the dots, while conversely the holes do not experience any barrier, which considerably increases the coupling. Results for the heteronuclear molecule show instead that its dots do not appear as two separate and distinguishable structures, but as a single large dot, and no optical emission is observed in the range of higher energies where the smaller dot is supposed to emit. We believe that in samples of such a high density the smaller dots result as practically incorporated into bigger molecular structures, an effect strongly enforced by the inter-dot strain fields, and consequently it is not possible to experimentally obtain a separate optical emission from the smaller dots.

  7. Annealing-induced change in quantum dot chain formation mechanism

    SciTech Connect

    Park, Tyler D.; Colton, John S.; Farrer, Jeffrey K.; Yang, Haeyeon; Kim, Dong Jun

    2014-12-15

    Self-assembled InGaAs quantum dot chains were grown using a modified Stranski-Krastanov method in which the InGaAs layer is deposited under a low growth temperature and high arsenic overpressure, which suppresses the formation of dots until a later annealing process. The dots are capped with a 100 nm GaAs layer. Three samples, having three different annealing temperatures of 460°C, 480°C, and 500°C, were studied by transmission electron microscopy. Results indicate two distinct types of dot formation processes: dots in the 460°C and 480°C samples form from platelet precursors in a one-to-one ratio whereas the dots in the sample annealed at 500°C form through the strain-driven self-assembly process, and then grow larger via an additional Ostwald ripening process whereby dots grow into larger dots at the expense of smaller seed islands. There are consequently significant morphological differences between the two types of dots, which explain many of the previously-reported differences in optical properties. Moreover, we also report evidence of indium segregation within the dots, with little or no indium intermixing between the dots and the surrounding GaAs barrier.

  8. Tunable Quantum Dot Solids: Impact of Interparticle Interactions on Bulk Properties

    SciTech Connect

    Sinclair, Michael B.; Fan, Hongyou; Brener, Igal; Liu, Sheng; Luk, Ting S.; Li, Binsong

    2015-09-01

    QD-solids comprising self-assembled semiconductor nanocrystals such as CdSe are currently under investigation for use in a wide array of applications including light emitting diodes, solar cells, field effect transistors, photodetectors, and biosensors. The goal of this LDRD project was develop a fundamental understanding of the relationship between nanoparticle interactions and the different regimes of charge and energy transport in semiconductor quantum dot (QD) solids. Interparticle spacing was tuned through the application of hydrostatic pressure in a diamond anvil cell, and the impact on interparticle interactions was probed using x-ray scattering and a variety of static and transient optical spectroscopies. During the course of this LDRD, we discovered a new, previously unknown, route to synthesize semiconductor quantum wires using high pressure sintering of self-assembled quantum dot crystals. We believe that this new, pressure driven synthesis approach holds great potential as a new tool for nanomaterials synthesis and engineering.

  9. Copenhagen Accord NAMA Submissions Implications for the Transport...

    OpenEI (Open Energy Information) [EERE & EIA]

    Organization: GTZ, Institute for Transportation and Development Policy (ITDP), Transport Research Laboratory(TRL), International Association for Public Transport (UITP), Veolia...

  10. Proposed mechanism to represent the suppression of dark current density by four orders with low energy light ion (H{sup ?}) implantation in quaternary alloy-capped InAs/GaAs quantum dot infrared photodetectors

    SciTech Connect

    Mandal, A.; Ghadi, H.; Mathur, K.L.; Basu, A.; Subrahmanyam, N.B.V.; Singh, P.; Chakrabarti, S.

    2013-08-01

    Graphical abstract: - Abstract: Here we propose a carrier transport mechanism for low energy H{sup ?} ions implanted InAs/GaAs quantum dot infrared photodetectors supportive of the experimental results obtained. Dark current density suppression of up to four orders was observed in the implanted quantum dot infrared photodetectors, which further demonstrates that they are effectively operational. We concentrated on determining how defect-related material and structural changes attributed to implantation helped in dark current density reduction for InAs/GaAs quantum dot infrared photodetectors. This is the first study to report the electrical carrier transport mechanism of H{sup ?} ion-implanted InAs/GaAs quantum dot infrared photodetectors.

  11. Reaction-Based Reactive Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center

    SciTech Connect

    Burgos, W.D.

    2009-09-02

    This report summarizes research conducted in conjunction with a project entitled “Reaction-Based Reactive Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center”, which was funded through the Integrative Studies Element of the former NABIR Program (now the Environmental Remediation Sciences Program) within the Office of Biological and Environmental Research. Dr. William Burgos (The Pennsylvania State University) was the overall PI/PD for the project, which included Brian Dempsey (Penn State), Gour-Tsyh (George) Yeh (Central Florida University), and Eric Roden (formerly at The University of Alabama, now at the University of Wisconsin) as separately-funded co-PIs. The project focused on development of a mechanistic understanding and quantitative models of coupled Fe(III)/U(VI) reduction in FRC Area 2 sediments. The work builds on our previous studies of microbial Fe(III) and U(VI) reduction, and was directly aligned with the Scheibe et al. ORNL FRC Field Project at Area 2.

  12. Current status, research needs, and opportunities in applications of surface processing to transportation and utilities technologies. Proceedings of a December 1991 workshop

    SciTech Connect

    Czanderna, A.W.; Landgrebe, A.R.

    1992-09-01

    Goal of surface processing is to develop innovative methods of surface modification and characterization for optimum performance and environmental protection for cost-effective operational lifetimes of systems, materials, and components used in transportation and utilities. These proceedings document the principal discussions and conclusions reached at the workshop; they document chapters about the current status of surface characterization with focus on composition, structure, bonding, and atomic-scale topography of surfaces. Also documented are chapters on the current status of surface modification techniques: electrochemical, plasma-aided, reactive and nonreactive physical vapor deposition, sol-gel coatings, high-energy ion implantation, ion-assisted deposition, organized molecular assemblies, solar energy. Brief chapters in the appendices document basic research in surface science by NSF, Air Force, and DOE. Participants at the workshop were invited to serve on 10 working groups. Separate abstracts were prepared for the data base where appropriate.

  13. Transportation and Parking

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Transportation and Parking

  14. Transportation | Argonne National Laboratory

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Technologies Available for Licensing Energy Storage Industrial & Manufacturing Processes Instrumentation & Devices Licensable Software Life Sciences Materials Transportation Fact Sheets and Forms Transportation Influencing the future of vehicles, fuels Argonne's transportation research efforts bring together scientists and engineers from many disciplines to find cost-effective solutions to critical issues like foreign-oil dependency and greenhouse gas emissions. As one of the U.S.

  15. Reaction-Based Transport Modeling of Iron Reduction and Uranium Immobilization at Area 2 of the NABIR Field Research Center

    SciTech Connect

    Yeh, Gour-Tsyh

    2006-06-01

    This research project (started Fall 2004) was funded by a grant to The Pennsylvania State University, University of Central Florida, and The University of Alabama in the Integrative Studies Element of the NABIR Program (DE-FG04-ER63914/63915/63196). Dr. Eric Roden, formerly at The University of Alabama, is now at the University of Wisconsin - Madison. Our project focuses on the development of a mechanistic understanding and quantitative models of coupled Fe(III)/U(VI) reduction in FRC Area 2 sediments. This work builds on our previous studies of microbial Fe(III) and U(VI) reduction, and is directly aligned with the Scheibe et al. NABIR FRC Field Project at Area 2.

  16. Theoretical performance of solar cell based on mini-bands quantum dots

    SciTech Connect

    Aly, Abou El-Maaty M. E-mail: ashraf.nasr@gmail.com; Nasr, A. E-mail: ashraf.nasr@gmail.com

    2014-03-21

    The tremendous amount of research in solar energy is directed toward intermediate band solar cell for its advantages compared with the conventional solar cell. The latter has lower efficiency because the photons have lower energy than the bandgap energy and cannot excite mobile carriers from the valence band to the conduction band. On the other hand, if mini intermediate band is introduced between the valence and conduction bands, then the smaller energy photons can be used to promote charge carriers transfer to the conduction band and thereby the total current increases while maintaining a large open circuit voltage. In this article, the influence of the new band on the power conversion efficiency for structure of quantum dots intermediate band solar cell is theoretically investigated and studied. The time-independent Schrödinger equation is used to determine the optimum width and location of the intermediate band. Accordingly, achievement of a maximum efficiency by changing the width of quantum dots and barrier distances is studied. Theoretical determination of the power conversion efficiency under the two different ranges of QD width is presented. From the obtained results, the maximum power conversion efficiency is about 70.42%. It is carried out for simple cubic quantum dot crystal under fully concentrated light. It is strongly dependent on the width of quantum dots and barrier distances.

  17. Long range emission enhancement and anisotropy in coupled quantum dots induced by aligned gold nanoantenna

    SciTech Connect

    Tripathi, L. N.; Praveena, M.; Valson, Pranay; Basu, J. K.

    2014-10-20

    Quantum dot arrays have been projected as the material of choice for next generation displays and photodetectors. Extensive ongoing research aims at improving optical and electrical efficiencies of such devices. We report experimental results on non-local long range emission intensity enhancement and anisotropy in quantum dot assemblies induced by isolated and partially aligned gold nanoantennas. Spatially resolved photoluminescence clearly demonstrate that the effect is maximum, when the longitudinal surface plasmon resonance of the nanoantenna is resonant with the emission maxima of the quantum dots. We estimated the decay length of this enhancement to be ∼2.6 μm, which is considerably larger than the range of near field interaction of metal nanoantenna. Numerical simulations qualitatively capture the near field behavior of the nanorods but fail to match the experimentally observed non-local effects. We have suggested how strong interactions of quantum dots in the close packed assemblies, mediated by the nanoantennas, could lead to such observed behavior.

  18. Radiation Transport

    SciTech Connect

    Urbatsch, Todd James

    2015-06-15

    We present an overview of radiation transport, covering terminology, blackbody raditation, opacities, Boltzmann transport theory, approximations to the transport equation. Next we introduce several transport methods. We present a section on Caseology, observing transport boundary layers. We briefly broach topics of software development, including verification and validation, and we close with a section on high energy-density experiments that highlight and support radiation transport.

  19. Research

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Research Research Isotopes produced at Los Alamos National Laboratory are saving lives, advancing cutting-edge research and keeping the U.S. safe. Research thorium test foil A thorium test foil target for proof-of-concept actinium-225 production In addition to our routine isotope products, the LANL Isotope Program is focused on developing the next suite of isotopes and services to meet the Nation's emerging needs. The LANL Isotope Program's R&D strategy is focused on four main areas (see

  20. The operation mechanism of poly(9,9-dioctylfluorenyl-2,7-diyl) dots in high efficiency polymer solar cells

    SciTech Connect

    Liu, Chunyu; He, Yeyuan; Zhang, Xinyuan; Li, Zhiqi; Li, Jinfeng; Zhang, Zhihui; Guo, Wenbin Ruan, Shengping; Shen, Liang

    2015-05-11

    The highly efficient polymer solar cells were realized by doping poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO) dots into active layer. The dependence of doping amount on devices performance was investigated and a high efficiency of 7.15% was obtained at an optimal concentration, accounting for a 22.4% enhancement. The incorporation of PFO dots (Pdots) is conducted to the improvement of J{sub sc} and fill factor mainly due to the enhancement of light absorption and charge transport property. Pdots blended in active layer provides an interface for charge transfer and enables the formation of percolation pathways for electron transport. The introduction of Pdots was proven an effective way to improve optical and electrical properties of solar cells.

  1. Enhancing efficiency and power of quantum-dots resonant tunneling thermoelectrics in three-terminal geometry by cooperative effects

    SciTech Connect

    Jiang, Jian-Hua

    2014-11-21

    We propose a scheme of multilayer thermoelectric engine where one electric current is coupled to two temperature gradients in three-terminal geometry. This is realized by resonant tunneling through quantum dots embedded in two thermal and electrical resisting polymer matrix layers between highly conducting semiconductor layers. There are two thermoelectric effects, one of which is pertaining to inelastic transport processes (if energies of quantum dots in the two layers are different), while the other exists also for elastic transport processes. These two correspond to the transverse and longitudinal thermoelectric effects, respectively, and are associated with different temperature gradients. We show that cooperation between the two thermoelectric effects leads to markedly improved figure of merit and power factor, which is confirmed by numerical calculation using material parameters. Such enhancement is robust against phonon heat conduction and energy level broadening. Therefore, we demonstrated cooperative effect as an additional way to effectively improve performance of thermoelectrics in three-terminal geometry.

  2. Controlling quantum dot energies using submonolayer bandstructure engineering

    SciTech Connect

    Yu, L.; Law, S.; Wasserman, D.; Jung, D.; Lee, M. L.; Shen, J.; Cha, J. J.

    2014-08-25

    We demonstrate control of energy states in epitaxially-grown quantum dot structures formed by stacked submonolayer InAs depositions via engineering of the internal bandstructure of the dots. Transmission electron microscopy of the stacked sub-monolayer regions shows compositional inhomogeneity, indicative of the presence of quantum dots. The quantum dot ground state is manipulated not only by the number of deposited InAs layers, but also by control of the thickness and material composition of the spacing layers between submonolayer InAs depositions. In this manner, we demonstrate the ability to shift the quantum dot ground state energy at 77?K from 1.38?eV to 1.88?eV. The results presented offer a potential avenue towards enhanced control of dot energies for a variety of optoelectronic applications.

  3. Fuel Cell Demonstration Project - 200 kW - Phosphoric Acid Fuel Cell Power Plant Located at the National Transportation Research Center: FINAL REPORT

    SciTech Connect

    Berry, JB

    2005-05-06

    Oak Ridge National Laboratory (ORNL) researches and develops distributed generation technology for the Department of Energy, Energy Efficiency and Renewable Energy Distributed Energy Program. This report describes installation and operation of one such distributed generation system, a United Technology Corporation fuel cell located at the National Transportation Research Center in Knoxville, Tennessee. Data collected from June 2003 to June of 2004, provides valuable insight regarding fuel cell-grid compatibility and the cost-benefit of the fuel cell operation. The NTRC fuel cell included a high-heat recovery option so that use of thermal energy improves project economics and improves system efficiency to 59% year round. During the year the fuel cell supplied a total of 834MWh to the NTRC and provided 300MBtu of hot water. Installation of the NTRC fuel cell was funded by the Distributed Energy Program with partial funding from the Department of Defense's Climate Change Fuel Cell Buy Down Program, administered by the National Energy Technology Laboratory. On-going operational expenses are funded by ORNL's utility budget and are paid from operational cost savings. Technical information and the benefit-cost of the fuel cell are both evaluated in this report and sister reports.

  4. Coupling of Time-Dependent Neutron Transport Theory with the Thermal Hydraulics Code ATHLET and Application to the Research Reactor FRM-II

    SciTech Connect

    Pautz, Andreas; Birkhofer, Adolf

    2003-11-15

    We introduce a new coupled neutronics/thermal hydraulics code system for analyzing transients of nuclear power plants and research reactors, based on a neutron transport theory approach. For the neutron kinetics, we have developed the code DORT-TD, a time-dependent extension of the well-known discrete ordinates code DORT. DORT-TD uses a fully implicit time integration scheme and is coupled via a general interface to the thermal hydraulics system code ATHLET, a generally applicable code for the analyses of LWR accident scenarios. Feedback is accounted for by interpolating multigroup cross sections from precalculated libraries, which are generated in advance for user-specified, discrete sets of thermal hydraulic parameters, e.g., fuel and coolant temperature. The coupled code system is applied to the high-flux research reactor FRM-II (Germany). Several design basis accidents are considered, namely the unintended control rod withdrawal, the loss of offsite power, and the loss of the secondary heat sink as well as a hypothetical transient with large reactivity insertion.

  5. The design and synthesis of heterostructured quantum dots with dual

    Office of Scientific and Technical Information (OSTI)

    emission in the visible and infrared (Journal Article) | SciTech Connect The design and synthesis of heterostructured quantum dots with dual emission in the visible and infrared Citation Details In-Document Search Title: The design and synthesis of heterostructured quantum dots with dual emission in the visible and infrared The unique optical properties exhibited by visible emitting core/shell quantum dots with especially thick shells are the focus of widespread study, but have yet to be

  6. Safety-analysis report for packaging - corrugated steel container (SAND Box) for DOT specification 7A packaging

    SciTech Connect

    Brugger, R.P.

    1983-05-16

    Department of Transportation (DOT) Specification 7A, Type A corrugated steel containers for shipment and storage of Transuranic (TRU) solid waste have been developed. The containers are made entirely of 14 gauge (0.0747-in.) low carbon steel. All seams including the closure are welded to produce a leak-tight container. Four sizes of the SAND Box container have successfully met all Specification 7A, Type A requirements.

  7. Safety analysis report for packaging-corrugated steel container (SAND Box) for DOT Specification 7A packaging

    SciTech Connect

    Brugger, R.P.

    1983-01-24

    Department of Transportation (DOT) Specification 7A, Type A corrugated steel containers for shipment and storage of Transuranic (TRU) solid waste have been developed. The containers are made entirely of 14 gauge (0.0747-in.) low carbon steel. All seams including the closure are welded to produce a leaktight container. Four sizes of the SAND Box container have successfully met all Specification 7A, Type A requirements.

  8. Solution-Processed Solar Cells using Colloidal Quantum Dots | MIT-Harvard

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Center for Excitonics Solution-Processed Solar Cells using Colloidal Quantum Dots September 27, 2012 at 3pm/36-428 Ted Sargent Department of Electrical and Computer Engineering - Canada Research Chair in Nanotechnology, University of Toronto, Canada sargent001_000 Abstract: Solution-processed photovoltaics offer a cost-effective path to harvesting the abundant resource that is solar energy. The organic and polymer semiconductors at the heart of these devices generally absorb visible light;

  9. Tuning Into the Right Wavelength: Quantum Dot Rainbow Increases Solar Cell

    Office of Science (SC)

    Efficiency | U.S. DOE Office of Science (SC) Tuning Into the Right Wavelength: Quantum Dot Rainbow Increases Solar Cell Efficiency Basic Energy Sciences (BES) BES Home About Research Facilities Science Highlights Benefits of BES Funding Opportunities Basic Energy Sciences Advisory Committee (BESAC) Community Resources Contact Information Basic Energy Sciences U.S. Department of Energy SC-22/Germantown Building 1000 Independence Ave., SW Washington, DC 20585 P: (301) 903-3081 F: (301)

  10. Interdot Coulomb correlation effects and spin-orbit coupling in two carbon nanotube quantum dots

    SciTech Connect

    Wang, Zhen-Hua; Kuang, Xiao-Yu Zhong, Ming-Min; Shao, Peng; Li, Hui

    2014-01-28

    Transport properties of the two-level Kondo effect involving spin, orbital, and pseudospin degrees of freedom are examined in a parallel carbon nanotube double quantum dot with a sufficient interdot Coulomb interaction and small interdot tunneling. The interdot Coulomb correlation effects are taken into account, and it plays an important role in forming bonding and antibonding states. Attached to ferromagnetic leads, the Kondo effect is observed at the interdot Coulomb blockade region with degeneracy of spin, orbital, and pseudospin degrees of freedom. A crossover from a two-level Kondo state involving the fivefold degeneracy of the double quantum dots to an SU(4) spin-orbit Kondo state and to an SU(2) spin-Kondo effect is demonstrated. At finite magnetic field, the splitting of the spin, orbital, and pseudospin Kondo resonance can be restored. For finite intradot Coulomb interaction U, there is a competition between the single-dot Kondo effect and the antiferromagnetic exchange coupling J{sub AFM}, resulting in the suppression of the Kondo resonance. Moreover, both the J{sub AFM} and the Zeeman interactions compete, leading to need a much higher value of the magnetic field to compensate for the Kondo splitting.

  11. Polarized quantum dot emission in electrohydrodynamic jet printed photonic crystals

    SciTech Connect

    See, Gloria G.; Xu, Lu; Nuzzo, Ralph G.; Sutanto, Erick; Alleyne, Andrew G.; Cunningham, Brian T.

    2015-08-03

    Tailored optical output, such as color purity and efficient optical intensity, are critical considerations for displays, particularly in mobile applications. To this end, we demonstrate a replica molded photonic crystal structure with embedded quantum dots. Electrohydrodynamic jet printing is used to control the position of the quantum dots within the device structure. This results in significantly less waste of the quantum dot material than application through drop-casting or spin coating. In addition, the targeted placement of the quantum dots minimizes any emission outside of the resonant enhancement field, which enables an 8× output enhancement and highly polarized emission from the photonic crystal structure.

  12. Ratiometric Sensing of Toxins using Quantum Dots | Argonne National...

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Ratiometric Sensing of Toxins using Quantum Dots December 4, 2015 Tweet EmailPrint Botulinum neurotoxin (BoNT) presents a significant hazard under numerous realistic scenarios. ...

  13. Unraveling the mystery of quantum-dot blinking

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Tiny particles with finely tunable electronic and optical properties Quantum dots are particles between 1 and 10 nanometers in diameter. A nanometer is only one billionth of a ...

  14. Exploring Competing Kinetic Processes in Quantum Dots Linked...

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Competing Kinetic Processes in Quantum Dots Linked to Electrode Surfaces March 14, 2012 at 2:30pm4-349 Mark Hybertsen Brookhaven National Laboratory, Columbia University ...

  15. Quantum Dot Tracers for Use in Engineered Geothermal

    Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)

    this project is to develop and demonstrate a new class of tracers, colloidal quantum dots, that offer great promise for use in characterizing fracture networks in EGS reservoirs. ...

  16. New Pathway Developed to Silicon Quantum Dot Devices (Fact Sheet...

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    for preparing doped colloids (solutions) of silicon nanocrystals (NCs) as potential nontoxic infrared-absorbing and -emitting alternatives to metal chalcogenide quantum dots. ...

  17. Search for: "quantum dots" | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    ... Quantum Dots Promise to Significantly Boost Solar Cell Efficiencies (Fact Sheet) Not Available In the search for a third generation of solar-cell technologies, a leading candidate ...

  18. Spin filtering in a double quantum dot device: Numerical renormalizati...

    Office of Scientific and Technical Information (OSTI)

    Country of Publication: United States Language: English Subject: 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; MATHEMATICAL MODELS; MATHEMATICAL SOLUTIONS; QUANTUM DOTS; ...

  19. Few Electron Quantum Dot coupling to Donor Implanted Electron...

    Office of Scientific and Technical Information (OSTI)

    Title: Few Electron Quantum Dot coupling to Donor Implanted Electron Spins. Abstract not provided. Authors: Rudolph, Martin ; Patrick Harvey-Collard ; Nielsen, Erik ; Gamble, John ...

  20. Diffusion-Controlled Synthesis of PbS and PbSe Quantum Dots with...

    Office of Scientific and Technical Information (OSTI)

    Dot Solar Cells Citation Details In-Document Search Title: Diffusion-Controlled Synthesis of PbS and PbSe Quantum Dots with in Situ Halide Passivation for Quantum Dot Solar Cells ...

  1. Emission switching in carbon dots coated CdTe quantum dots driving by pH dependent hetero-interactions

    SciTech Connect

    Dai, Xiao; Wang, Hao; Yi, Qinghua; Wang, Yun; Cong, Shan; Zhao, Jie; Sun, Yinghui; Zou, Guifu E-mail: jiexiong@uestc.edu.cn; Qian, Zhicheng; Huang, Jianwen; Xiong, Jie E-mail: jiexiong@uestc.edu.cn; Luo, Hongmei

    2015-11-16

    Due to the different emission mechanism between fluorescent carbon dots and semiconductor quantum dots (QDs), it is of interest to explore the potential emission in hetero-structured carbon dots/semiconducting QDs. Herein, we design carbon dots coated CdTe QDs (CDQDs) and investigate their inherent emission. We demonstrate switchable emission for the hetero-interactions of the CDQDs. Optical analyses indicate electron transfer between the carbon dots and the CdTe QDs. A heterojunction electron process is proposed as the driving mechanism based on N atom protonation of the carbon dots. This work advances our understanding of the interaction mechanism of the heterostructured CDQDs and benefits the future development of optoelectronic nanodevices with new functionalities.

  2. Research

    SciTech Connect

    1999-10-01

    Subjects covered in this section are: (1) PCAST panel promotes energy research cooperation; (2) Letter issued by ANS urges funding balance in FFTF restart consideration and (3) FESAC panel releases report on priorities and balance.

  3. Research

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    The LANL Isotope Program's R&D strategy is focused on four main areas (see article list below for recent efforts in these areas): Medical Applications are a key focus for research ...

  4. The Oak Ridge Field Research Center : Advancing Scientific Understanding of the Transportation, Fate, and Remediation of Subsurface Contamination Sources and Plumes

    SciTech Connect

    David Watson

    2005-04-18

    Historical research, development, and testing of nuclear materials across this country resulted in subsurface contamination that has been identified at over 7,000 discrete sites across the U.S. Department of Energy (DOE) complex. With the end of the Cold War threat, DOE has shifted its emphasis to remediation, decommissioning, and decontamination of the immense volumes of contaminated groundwater, sediments, and structures at its sites. DOE currently is responsible for remediating 1.7 trillion gallons of contaminated groundwater, an amount equal to approximately four times the daily U.S. water consumption, and 40 million cubic meters of contaminated soil, enough to fill approximately 17 professional sports stadiums.* DOE also sponsors research intended to improve or develop remediation technologies, especially for difficult, currently intractable contaminants or conditions. The Oak Ridge FRC is representative of some difficult sites, contaminants, and conditions. Buried wastes in contact with a shallow water table have created huge reservoirs of contamination. Rainfall patterns affect the water table level seasonally and over time. Further, the hydrogeology of the area, with its fractures and karst geology, affects the movement of contaminant plumes. Plumes have migrated long distances and to surface discharge points through ill-defined preferred flowpaths created by the fractures and karst conditions. From the standpoint of technical effectiveness, remediation options are limited, especially for contaminated groundwater. Moreover, current remediation practices for the source areas, such as capping, can affect coupled processes that, in turn, may affect the movement of subsurface contaminants in unknown ways. Research conducted at the FRC or with FRC samples therefore promotes understanding of the processes that influence the transport and fate of subsurface contaminants, the effectiveness and long-term consequences of extant remediation options, and the

  5. Kondo time scales for quantum dots: Response to pulsed bias potentials

    SciTech Connect

    Plihal, Martin; Langreth, David C.; Nordlander, Peter

    2000-05-15

    The response of a quantum dot in the Kondo regime to rectangular pulsed bias potentials of various strengths and durations is studied theoretically. It is found that the rise time is faster than the fall time, and also faster than time scales normally associated with the Kondo problem. For larger values of the pulsed bias, one can induce dramatic oscillations in the induced current with a frequency approximating the splitting between the Kondo peaks that would be present in steady state. The effect persists in the total charge transported per pulse, which should facilitate the experimental observation of the phenomenon. (c) 2000 The American Physical Society.

  6. Three dimensional time-gated tracking of non-blinking quantum dots in live cells

    DOE PAGES [OSTI]

    DeVore, Matthew S.; Werner, James H.; Goodwin, Peter M.; Keller, Aaron M.; Hollingsworth, Jennifer A.; Wilson, Bridget S.; Cleyrat, Cedric; Lidke, Diane S.; Ghosh, Yagnaseni; Stewart, Michael H.; et al

    2015-03-12

    Single particle tracking has provided a wealth of information about biophysical processes such as motor protein transport and diffusion in cell membranes. However, motion out of the plane of the microscope or blinking of the fluorescent probe used as a label generally limits observation times to several seconds. Here, we overcome these limitations by using novel non-blinking quantum dots as probes and employing a custom 3D tracking microscope to actively follow motion in three dimensions (3D) in live cells. As a result, signal-to-noise is improved in the cellular milieu through the use of pulsed excitation and time-gated detection.

  7. Three dimensional time-gated tracking of non-blinking quantum dots in live cells

    SciTech Connect

    DeVore, Matthew S.; Werner, James H.; Goodwin, Peter M.; Keller, Aaron M.; Hollingsworth, Jennifer A.; Wilson, Bridget S.; Cleyrat, Cedric; Lidke, Diane S.; Ghosh, Yagnaseni; Stewart, Michael H.; Stich, Dominik G.; Phipps, Mary E.

    2015-12-03

    Single particle tracking has provided a wealth of information about biophysical processes such as motor protein transport and diffusion in cell membranes. However, motion out of the plane of the microscope or blinking of the fluorescent probe used as a label generally limits observation times to several seconds. Here, we overcome these limitations by using novel non-blinking quantum dots as probes and employing a custom 3D tracking microscope to actively follow motion in three dimensions (3D) in live cells. As a result, signal-to-noise is improved in the cellular milieu through the use of pulsed excitation and time-gated detection.

  8. Packaging and Transportation for Offsite Shipment of Materials of National Security Interest

    Directives, Delegations, and Other Requirements [Office of Management (MA)]

    2016-07-20

    The purpose of this Order is to make clear that the packaging and transportation of all offsite shipments of Materials of National Security Interest (MNSI) for DOE must be conducted in accordance with Department of Transportation (DOT) and Nuclear Regulatory Commission (NRC) regulations that would be applicable to comparable commercial shipments, except where an alternative course of action is identified in this Order.

  9. Applicability of the {bold k}{center_dot}{bold p} method to the electronic structure of quantum dots

    SciTech Connect

    Fu, H.; Wang, L.; Zunger, A.

    1998-04-01

    The {bold k}{center_dot}{bold p} method has become the {open_quotes}standard model{close_quotes} for describing the electronic structure of nanometer-size quantum dots. In this paper we perform parallel {bold k}{center_dot}{bold p} (6{times}6 and 8{times}8) and direct-diagonalization pseudopotential studies on spherical quantum dots of an ionic material{emdash}CdSe, and a covalent material{emdash}InP. By using an equivalent input in both approaches, i.e., starting from a given atomic pseudopotential and deriving from it the Luttinger parameters in {bold k}{center_dot}{bold p} calculation, we investigate the effect of the different underlying wave-function representations used in {bold k}{center_dot}{bold p} and in the more exact pseudopotential direct diagonalization. We find that (i) the 6{times}6{bold k}{center_dot}{bold p} envelope function has a distinct (odd or even) parity, while atomistic wave function is parity-mixed. The 6{times}6{bold k}{center_dot}{bold p} approach produces an incorrect order of the highest valence states for both InP and CdSe dots: the p-like level is above the s-like level. (ii) It fails to reveal that the second conduction state in small InP dots is folded from the L point in the Brillouin zone. Instead, all states in {bold k}{center_dot}{bold p} are described as {Gamma}-like. (iii) The {bold k}{center_dot}{bold p} overestimates the confinement energies of both valence states and conduction states. A wave-function projection analysis shows that the principal reasons for these {bold k}{center_dot}{bold p} errors in dots are (a) use of restricted basis set, and (b) incorrect {ital bulk} dispersion relation. Error (a) can be reduced only by increasing the number of basis functions. Error (b) can be reduced by altering the {bold k}{center_dot}{bold p} implementation so as to bend upwards the second lowest bulk band, and to couple the conduction band into the s-like dot valence state. Our direct diagonalization approach provides an

  10. ISSUES ASSOCIATED WITH SAFE PACKAGING AND TRANSPORT OF NANOPARTICLES

    SciTech Connect

    Gupta, N.; Smith, A.

    2011-02-14

    Nanoparticles have long been recognized a hazardous substances by personnel working in the field. They are not, however, listed as a separate, distinct category of dangerous goods at present. As dangerous goods or hazardous substances, they require packaging and transportation practices which parallel the established practices for hazardous materials transport. Pending establishment of a distinct category for such materials by the Department of Transportation, existing consensus or industrial protocols must be followed. Action by DOT to establish appropriate packaging and transport requirements is recommended.

  11. NREL: Transportation Research - Fuel Chemistry Research

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    NREL evaluates a broad range of renewable gasoline and diesel fuels-ranging from currently available ethanol and biodiesel to future products such as dimethyl furan and ...

  12. Geological Sequestration Training and Research Program in Capture and Transport: Development of the Most Economical Separation Method for CO2 Capture

    SciTech Connect

    Vahdat, Nader

    2013-09-30

    The project provided hands-on training and networking opportunities to undergraduate students in the area of carbon dioxide (CO2) capture and transport, through fundamental research study focused on advanced separation methods that can be applied to the capture of CO2 resulting from the combustion of fossil-fuels for power generation . The project team’s approach to achieve its objectives was to leverage existing Carbon Capture and Storage (CCS) course materials and teaching methods to create and implement an annual CCS short course for the Tuskegee University community; conduct a survey of CO2 separation and capture methods; utilize data to verify and develop computer models for CO2 capture and build CCS networks and hands-on training experiences. The objectives accomplished as a result of this project were: (1) A comprehensive survey of CO2 capture methods was conducted and mathematical models were developed to compare the potential economics of the different methods based on the total cost per year per unit of CO2 avoidance; and (2) Training was provided to introduce the latest CO2 capture technologies and deployment issues to the university community.

  13. ARM - Research Highlights

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    CenterResearch Highlights Media Contact Hanna Goss hanna-dot-goss-at-pnnl-dot-gov @armnewsteam Field Notes Blog Topics Field Notes118 AGU 3 AMIE 10 ARM Aerial Facility 2 ARM Mobile Facility 1 7 ARM Mobile Facility 2 47 ARM Mobile Facility 3 1 BAECC 1 BBOP 4 CARES 1 Data Quality Office 2 ENA 2 GOAMAZON 7 HI-SCALE 5 LASIC 3 MAGIC 15 MC3E 17 PECAN 3 SGP 8 STORMVEX 29 TCAP 3 Search News Search Blog News Center All Categories What's this? Social Media Guidance News Center All Categories Features and

  14. Current Research

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Current Research The U.S. Department of Transportation (USDOT) has established its only high-performance computing and engineering analysis research facility at Argonne National Laboratory to provide applications support in key areas of applied research and development for the USDOT community. The Transportation Research and Analysis Computing Center (TRACC) features a state-of-the-art massively parallel computer system, advanced scientific visualization capability, high-speed network

  15. Going the Distance? NRC's Response to the National Academy of Science's Transportation Study

    SciTech Connect

    Easton, E.P.; Bajwa, C.S.

    2008-07-01

    In February 2006, the National Academy of Sciences (NAS) published the results of a 3 1/2-year study, titled Going the Distance, that examined the safety of transporting spent nuclear fuel (SNF) and high level waste (HLW) in the United States. NAS initiated this study to address what it perceived to be a national need for an independent, objective, and authoritative analysis of SNF and HLW transport in the United States. The study was co-sponsored by the U.S. Nuclear Regulatory Commission (NRC), the U.S. Department of Energy (DOE), the U.S. Department of Transportation (DOT), the Electric Power Research Institute and the National Cooperative Highway Research Program. This paper addresses some of the recommendations made in the NAS study related to the performance of SNF transportation casks in long duration fires, the use of full-scale package testing, and the need for an independent review of transportation security prior to the commencement of large scale shipping campaigns to an interim storage site or geologic repository. In conclusion: The NRC believes that the current regulations in 10 CFR Part 71 for the design of SNF and HLW transportation packages provide a very high level of protection to the public for very severe accidents and credible threat scenarios. As recommended by the NAS study, additional studies of accidents involving severe fires have been completed. These studies have confirmed that spent fuel casks would be expected to withstand very severe fires without the release of any fission products from the spent fuel. Additionally, changes in rail operating procedures such as the use of dedicated trains and prohibition on the co-location of SNF and flammable liquids in rail tunnels can further reduce the already low probability of severe rail accident fires involving SNF and HLW. (authors)

  16. Research

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Research CORE-SHELL NANOPARTICLES AND NANOSTRUCTURED MESOPOROUS MATERIALS(NMMs) Nanomaterials need no special introduction as interest in them sparked exponential growth in the past couple of decades, not only in scientific laboratories but also in industries around the world. In addition to size and shape effects, newer designs of nanostructures have also begun gaining prominence providing a new opportunity to tailor the properties of nanomaterials and investigate their fundamental behavior as

  17. Beam Transport

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Beam Transport A simplified drawing of the beam transport system from the linac to Target-1 (Lujan Center), Target-2 (Blue Room) and Target-4 is shown below. In usual operation ...

  18. Kondo effect in coupled quantum dots under magnetic fields

    SciTech Connect

    Aono, Tomosuke; Eto, Mikio

    2001-08-15

    The Kondo effect in coupled quantum dots is investigated theoretically under magnetic fields. We show that the magnetoconductance (MC) illustrates the peak structures of Kondo resonant spectra. When the dot-dot tunneling coupling V{sub C} is smaller than the dot-lead coupling {Delta} (level broadening), Kondo resonant levels appear at the Fermi level (E{sub F}). The Zeeman splitting of the levels weakens the Kondo effect, which results in a negative MC. When V{sub C} is larger than {Delta}, the Kondo resonances form bonding and antibonding levels, located below and above E{sub F}, respectively. We observe a positive MC since the Zeeman splitting increases the overlap between the levels at E{sub F}. In the presence of antiferromagnetic spin coupling between the dots, the sign of the MC can change as a function of the gate voltage.

  19. Numerical simulation of optical feedback on a quantum dot lasers

    SciTech Connect

    Al-Khursan, Amin H.; Ghalib, Basim Abdullattif; Al-Obaidi, Sabri J.

    2012-02-15

    We use multi-population rate equations model to study feedback oscillations in the quantum dot laser. This model takes into account all peculiar characteristics in the quantum dots such as inhomogeneous broadening of the gain spectrum, the presence of the excited states on the quantum dot and the non-confined states due to the presence of wetting layer and the barrier. The contribution of quantum dot groups, which cannot follow by other models, is simulated. The results obtained from this model show the feedback oscillations, the periodic oscillations which evolves to chaos at higher injection current of higher feedback levels. The frequency fluctuation is attributed mainly to wetting layer with a considerable contribution from excited states. The simulation shows that is must be not using simple rate equation models to express quantum dots working at excited state transition.

  20. WIPP Transportation

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Transuranic Waste Transportation Container Documents Documents related to transuranic waste containers and packages. CBFO Tribal Program Information about WIPP shipments across tribal lands. Transportation Centralized Procurement Program - The Centralized Procurement Program provides a common method to procure standard items used in the packaging and handling of transuranic wasted destined for WIPP. Transuranic Waste Transportation Routes - A map showing transuranic waste generator sites and

  1. Approaches to Future Generation Photovoltaics and Solar Fuels: Multiple Exciton Generation in Quantum Dots, Quantum Dot Arrays, Molecular Singlet Fission, and Quantum Dot Solar Cells

    SciTech Connect

    Nozik, A. J.; Beard, M. C.; Johnson, J. C.; Hanna, M. C.; Luther, J. M.; Midgett, A.; Semonin, O.; Michel, J.

    2012-01-01

    One potential, long-term approach to more efficient future generation solar cells is to utilize the unique properties of quantum dots (QDs) and unique molecular chromophores to control the relaxation pathways of excited states to produce enhanced conversion efficiency through efficient multiple electron-hole pair generation from single photons . We have observed efficient multiple exciton generation (MEG) in PbSe, PbS, PbTe, and Si QDs and efficient singlet fission (SF) in molecules that satisfy specific requirements for their excited state energy level structure to achieve carrier multiplication. We have studied MEG in close-packed QD arrays where the QDs are electronically coupled in the films and thus exhibit good transport while still maintaining quantization and MEG. We have developed simple, all-inorganic QD solar cells that produce large short-circuit photocurrents and power conversion efficiencies in the 3-5% range via both nanocrystalline Schottky junctions and nanocrystalline p-n junctions. These solar cells also show QYs for photocurrent that exceed 100% in the photon energy regions where MEG is possible; the photocurrent MEG QYs as a function of photon energy match those determined via time-resolved spectroscopy. We have also observed very efficient SF in thin films of molecular crystals of 1,3 diphenylisobenzofuran with quantum yields of 200% at the optimum SF threshold of 2Eg (HOMO-LUMO for S{sub 0}-S{sub 1}), reflecting the creation of two excited triplet states from the first excited singlet state. Various possible configurations for novel solar cells based on MEG in QDs and SF in molecules that could produce high conversion efficiencies will be presented, along with progress in developing such new types of solar cells. Recent analyses of the effect of MEG or SF combined with solar concentration on the conversion efficiency of solar cells will be discussed.

  2. Competing interactions in semiconductor quantum dots

    DOE PAGES [OSTI]

    van den Berg, R.; Brandino, G. P.; El Araby, O.; Konik, R. M.; Gritsev, V.; Caux, J. -S.

    2014-10-14

    In this study, we introduce an integrability-based method enabling the study of semiconductor quantum dot models incorporating both the full hyperfine interaction as well as a mean-field treatment of dipole-dipole interactions in the nuclear spin bath. By performing free induction decay and spin echo simulations we characterize the combined effect of both types of interactions on the decoherence of the electron spin, for external fields ranging from low to high values. We show that for spin echo simulations the hyperfine interaction is the dominant source of decoherence at short times for low fields, and competes with the dipole-dipole interactions atmore » longer times. On the contrary, at high fields the main source of decay is due to the dipole-dipole interactions. In the latter regime an asymmetry in the echo is observed. Furthermore, the non-decaying fraction previously observed for zero field free induction decay simulations in quantum dots with only hyperfine interactions, is destroyed for longer times by the mean-field treatment of the dipolar interactions.« less

  3. Competing interactions in semiconductor quantum dots

    SciTech Connect

    van den Berg, R.; Brandino, G. P.; El Araby, O.; Konik, R. M.; Gritsev, V.; Caux, J. -S.

    2014-10-14

    In this study, we introduce an integrability-based method enabling the study of semiconductor quantum dot models incorporating both the full hyperfine interaction as well as a mean-field treatment of dipole-dipole interactions in the nuclear spin bath. By performing free induction decay and spin echo simulations we characterize the combined effect of both types of interactions on the decoherence of the electron spin, for external fields ranging from low to high values. We show that for spin echo simulations the hyperfine interaction is the dominant source of decoherence at short times for low fields, and competes with the dipole-dipole interactions at longer times. On the contrary, at high fields the main source of decay is due to the dipole-dipole interactions. In the latter regime an asymmetry in the echo is observed. Furthermore, the non-decaying fraction previously observed for zero field free induction decay simulations in quantum dots with only hyperfine interactions, is destroyed for longer times by the mean-field treatment of the dipolar interactions.

  4. Safety analysis report for packaging a DOT 7A specification container for tritiated liquid wastes

    SciTech Connect

    Alford, E.

    1980-08-01

    This Safety Analysis Report for Packaging (SARP) was prepared in accordance with ERDA (DOE) Appendix 5201 for DOE/ALO review and approval of packaging of tritiated liquid wastes to be shipped from Sandia National Laboratories, Livermore, (SNLL) California. This report presents information pertinent to the construction of tritiated liquid waste shipping containers. It contains design and development considerations, explains tests and evaluations required to prove the container can withstand normal transportation conditions, and demonstrates that the Sandia container-and-radioactive-material shipment package is in compliance with DOE and Department of Transportation (DOT) safety requirements. An internal review of this SARP has been performed in compliance with the ERDA (DOE) Manual, 5201 Appendix V.

  5. ostiblog_image_quantum_dots_smaller.png | OSTI, US Dept of Energy Office of

    Office of Scientific and Technical Information (OSTI)

    Scientific and Technical Information ostiblog_image_quantum_dots_smaller.png

  6. sci_showcase_quantum_dots.png | OSTI, US Dept of Energy Office of

    Office of Scientific and Technical Information (OSTI)

    Scientific and Technical Information sci_showcase_quantum_dots.png

  7. Coherent radiation by quantum dots and magnetic nanoclusters

    SciTech Connect

    Yukalov, V. I.; Yukalova, E. P.

    2014-03-31

    The assemblies of either quantum dots or magnetic nanoclusters are studied. It is shown that such assemblies can produce coherent radiation. A method is developed for solving the systems of nonlinear equations describing the dynamics of such assemblies. The method is shown to be general and applicable to systems of different physical nature. Despite mathematical similarities of dynamical equations, the physics of the processes for quantum dots and magnetic nanoclusters is rather different. In a quantum dot assembly, coherence develops due to the Dicke effect of dot interactions through the common radiation field. For a system of magnetic clusters, coherence in the spin motion appears due to the Purcell effect caused by the feedback action of a resonator. Self-organized coherent spin radiation cannot arise without a resonator. This principal difference is connected with the different physical nature of dipole forces between the objects. Effective dipole interactions between the radiating quantum dots, appearing due to photon exchange, collectivize the dot radiation. While the dipolar spin interactions exist from the beginning, yet before radiation, and on the contrary, they dephase spin motion, thus destroying the coherence of moving spins. In addition, quantum dot radiation exhibits turbulent photon filamentation that is absent for radiating spins.

  8. Carrier multiplication detected through transient photocurrent in device-grade films of lead selenide quantum dots

    DOE PAGES [OSTI]

    Gao, Jianbo; Fidler, Andrew F.; Klimov, Victor I.

    2015-09-08

    In carrier multiplication, the absorption of a single photon results in two or more electron–hole pairs. Quantum dots are promising materials for implementing carrier multiplication principles in real-life technologies. So far, however, most of research in this area has focused on optical studies of solution samples with yet to be proven relevance to practical devices. We report ultra-fast electro-optical studies of device-grade films of electronically coupled quantum dots that allow us to observe multiplication directly in the photocurrent. Our studies help rationalize previous results from both optical spectroscopy and steady-state photocurrent measurements and also provide new insights into effects ofmore » electric field and ligand treatments on multiexciton yields. Importantly, we demonstrate that using appropriate chemical treatments of the films, extra charges produced by carrier multiplication can be extracted from the quantum dots before they are lost to Auger recombination and hence can contribute to photocurrent of practical devices.« less

  9. Coupling capacitance between double quantum dots tunable by the number of electrons in Si quantum dots

    SciTech Connect

    Uchida, Takafumi Arita, Masashi; Takahashi, Yasuo; Fujiwara, Akira

    2015-02-28

    Tunability of capacitive coupling in the Si double-quantum-dot system is discussed by changing the number of electrons in quantum dots (QDs), in which the QDs are fabricated using pattern-dependent oxidation (PADOX) of a Si nanowire and multi-fine-gate structure. A single QD formed by PADOX is divided into multiple QDs by additional oxidation through the gap between the fine gates. When the number of electrons occupying the QDs is large, the coupling capacitance increases gradually and almost monotonically with the number of electrons. This phenomenon is attributed to the gradual growth in the effective QD size due to the increase in the number of electrons in the QDs. On the other hand, when the number of electrons changes in the few-electron regime, the coupling capacitance irregularly changes. This irregularity can be observed even up to 40 electrons. This behavior is attributable the rough structure of Si nano-dots made by PADOX. This roughness is thought to induce complicated change in the electron wave function when an electron is added to or subtracted from a QD.

  10. Zeno-logic applications of semiconductor quantum dots

    SciTech Connect

    Schneebeli, L.; Peyghambarian, N.; Feldtmann, T.; Kira, M.; Koch, S. W.

    2010-05-15

    Microscopic calculations show that CdSe-based semiconductor quantum dots with confined exciton and biexciton states are suitable candidates for Zeno-logic applications. The frequencies of the control and signal fields are chosen to guarantee very high transmission of the individual beams. If both fields are present simultaneously, they are strongly absorbed due to efficient ground-state-to-biexciton transitions. The optical Bloch equations for a three-level quantum-dot model with self-consistent light-matter coupling are solved numerically. The influence of dephasing and/or inhomogeneous dot distributions is analyzed and the conditions for satisfactory device operation are identified.

  11. Generation of even harmonics in coupled quantum dots

    SciTech Connect

    Guo Shifang; Duan Suqing; Yang Ning; Chu Weidong; Zhang Wei

    2011-07-15

    Using the spatial-temporal symmetry principle we developed recently, we propose an effective scheme for even-harmonics generation in coupled quantum dots. The relative intensity of odd and even harmonic components in the emission spectrum can be controlled by tuning the dipole couplings among the dots, which can be realized in experiments by careful design of the nanostructures. In particular, pure 2nth harmonics and (2n+1)th harmonics (where n is an integer) can be generated simultaneously with polarizations in two mutual perpendicular directions in our systems. An experimental design of the coupled dots system is presented.

  12. Greening Transportation

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Transportation Goal 2: Greening Transportation LANL supports and encourages employees to reduce their personal greenhouse gas emissions by offering various commuting and work schedule options. Our goal is to reduce emissions related to employee travel and commuting to and from work by 13 percent. Energy Conservation» Efficient Water Use & Management» High Performance Sustainable Buildings» Greening Transportation» Green Purchasing & Green Technology» Pollution Prevention» Science

  13. Charge sensing of a few-donor double quantum dot in silicon

    SciTech Connect

    Watson, T. F. Weber, B.; Büch, H.; Fuechsle, M.; Simmons, M. Y.

    2015-12-07

    We demonstrate the charge sensing of a few-donor double quantum dot precision placed with atomic resolution scanning tunnelling microscope lithography. We show that a tunnel-coupled single electron transistor (SET) can be used to detect electron transitions on both dots as well as inter-dot transitions. We demonstrate that we can control the tunnel times of the second dot to the SET island by ∼4 orders of magnitude by detuning its energy with respect to the first dot.

  14. Quantum Dot Tracers for Use in Engineered Geothermal | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)

    Quantum Dot Tracers for Use in Engineered Geothermal Quantum Dot Tracers for Use in Engineered Geothermal Quantum Dot Tracers for Use in Engineered Geothermal presentation at the April 2013 peer review meeting held in Denver, Colorado. quantum_dot_tracers_peer2013.pdf (1.08 MB) More Documents & Publications Tracer Methods for Characterizing Fracture Stimulation in Engineered Geothermal Systems (EGS) Quantum Dot Tracers for Use in Engineered Geothermal Systems Use of Tracers to Characterize

  15. Electron states in semiconductor quantum dots

    SciTech Connect

    Dhayal, Suman S.; Ramaniah, Lavanya M.; Ruda, Harry E.; Nair, Selvakumar V.

    2014-11-28

    In this work, the electronic structures of quantum dots (QDs) of nine direct band gap semiconductor materials belonging to the group II-VI and III-V families are investigated, within the empirical tight-binding framework, in the effective bond orbital model. This methodology is shown to accurately describe these systems, yielding, at the same time, qualitative insights into their electronic properties. Various features of the bulk band structure such as band-gaps, band curvature, and band widths around symmetry points affect the quantum confinement of electrons and holes. These effects are identified and quantified. A comparison with experimental data yields good agreement with the calculations. These theoretical results would help quantify the optical response of QDs of these materials and provide useful input for applications.

  16. Sustainable Transportation

    SciTech Connect

    2012-09-01

    This document highlights DOE's Office of Energy Efficiency and Renewable Energy's advancements in transportation technologies, alternative fuels, and fuel cell technologies.

  17. DOT Beyond Traffic Smart City Challenge

    Energy.gov [DOE]

    The U.S. Department of Transportation is accepting applications for the Smart City Challenge to one mid-sized city that can demonstrate how advanced data and intelligent transportation system technologies and applications can be used to reduce congestion, protect the environment, respond to climate change, and support economic vitality.

  18. NREL: Biomass Research - Facilities

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Facilities At NREL's state-of-the-art biomass research facilities, researchers design and optimize processes to convert renewable biomass feedstocks into transportation fuels and...

  19. A triple quantum dot based nano-electromechanical memory device

    SciTech Connect

    Pozner, R.; Lifshitz, E.; Peskin, U.

    2015-09-14

    Colloidal quantum dots (CQDs) are free-standing nano-structures with chemically tunable electronic properties. This tunability offers intriguing possibilities for nano-electromechanical devices. In this work, we consider a nano-electromechanical nonvolatile memory (NVM) device incorporating a triple quantum dot (TQD) cluster. The device operation is based on a bias induced motion of a floating quantum dot (FQD) located between two bound quantum dots (BQDs). The mechanical motion is used for switching between two stable states, “ON” and “OFF” states, where ligand-mediated effective interdot forces between the BQDs and the FQD serve to hold the FQD in each stable position under zero bias. Considering realistic microscopic parameters, our quantum-classical theoretical treatment of the TQD reveals the characteristics of the NVM.

  20. Quantum dot conjugates in a sub-micrometer fluidic channel

    DOEpatents

    Stavis, Samuel M.; Edel, Joshua B.; Samiee, Kevan T.; Craighead, Harold G.

    2008-07-29

    A nanofluidic channel fabricated in fused silica with an approximately 500 nm square cross section was used to isolate, detect and identify individual quantum dot conjugates. The channel enables the rapid detection of every fluorescent entity in solution. A laser of selected wavelength was used to excite multiple species of quantum dots and organic molecules, and the emission spectra were resolved without significant signal rejection. Quantum dots were then conjugated with organic molecules and detected to demonstrate efficient multicolor detection. PCH was used to analyze coincident detection and to characterize the degree of binding. The use of a small fluidic channel to detect quantum dots as fluorescent labels was shown to be an efficient technique for multiplexed single molecule studies. Detection of single molecule binding events has a variety of applications including high throughput immunoassays.

  1. Quantum dot conjugates in a sub-micrometer fluidic channel

    DOEpatents

    Stavis, Samuel M.; Edel, Joshua B.; Samiee, Kevan T.; Craighead, Harold G.

    2010-04-13

    A nanofluidic channel fabricated in fused silica with an approximately 500 nm square cross section was used to isolate, detect and identify individual quantum dot conjugates. The channel enables the rapid detection of every fluorescent entity in solution. A laser of selected wavelength was used to excite multiple species of quantum dots and organic molecules, and the emission spectra were resolved without significant signal rejection. Quantum dots were then conjugated with organic molecules and detected to demonstrate efficient multicolor detection. PCH was used to analyze coincident detection and to characterize the degree of binding. The use of a small fluidic channel to detect quantum dots as fluorescent labels was shown to be an efficient technique for multiplexed single molecule studies. Detection of single molecule binding events has a variety of applications including high throughput immunoassays.

  2. Comparison of quantum confinement effects between quantum wires and dots

    SciTech Connect

    Li, Jingbo; Wang, Lin-Wang

    2004-03-30

    Dimensionality is an important factor to govern the electronic structures of semiconductor nanocrystals. The quantum confinement energies in one-dimensional quantum wires and zero-dimensional quantum dots are quite different. Using large-scale first-principles calculations, we systematically study the electronic structures of semiconductor (including group IV, III-V, and II-VI) surface-passivated quantum wires and dots. The band-gap energies of quantum wires and dots have the same scaling with diameter for a given material. The ratio of band-gap-increases between quantum wires and dots is material-dependent, and slightly deviates from 0.586 predicted by effective-mass approximation. Highly linear polarization of photoluminescence in quantum wires is found. The degree of polarization decreases with the increasing temperature and size.

  3. TxDOT Access Management Manual | Open Energy Information

    OpenEI (Open Energy Information) [EERE & EIA]

    Access Management Manual Jump to: navigation, search OpenEI Reference LibraryAdd to library Legal Document- OtherOther: TxDOT Access Management ManualLegal Abstract Manual prepared...

  4. Synthesis of Non-blinking Semiconductor Quantum Dots Emitting...

    Office of Scientific and Technical Information (OSTI)

    Our previous work demonstrates that Quasi-Type II CdSeCdS core-shell quantum dots with ... synthesized to reduce cadmium exposure for applications in the biological environment. ...

  5. Quantum Dot Tracers for Use in Engineered Geothermal Systems

    Energy.gov [DOE]

    DOE Geothermal Peer Review 2010 - Presentation. Project objective: To develop and demonstrate a new class of tracers„semiconductor nanoparticles(quantum dots)„that offer great promise for use in characterizing fracture networks in EGS reservoirs.

  6. Pulsed Thermal Processing of Self-Assembled Quantum Dot Structures

    SciTech Connect

    2009-04-01

    This factsheet describes a study that will develop the quantum dot manufacturing system for roll-to-roll thin film processing for use in applications such as solid state lighting.

  7. Collective modes of quantum dot ensembles in microcavities

    SciTech Connect

    Averkiev, N. S.; Glazov, M. M. Poddubnyi, A. N.

    2009-05-15

    Emission spectra of quantum dot arrays in zero-dimensional microcavities are studied theoretically. It is shown that their form is determined by the competition between collective superradiant mode formation and inhomogeneous broadening. A random sources method is used to calculate the photoluminescence spectra from an nonresonant pumped microcavity, and a standard diagram technique is used to provide a microscopic justification for the random sources method. The emission spectra of a microcavity are analyzed taking into account the spread of exciton energy due to inhomogeneous distribution of quantum dots and tunneling between them. It is demonstrated that the luminescence spectra of strongly tunnel-coupled quantum dots are sensitive to the dot positions, and the collective mode can (under certain conditions) be stabilized by random tunneling links.

  8. Shiny quantum dots brighten future of solar cells

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Photovoltaic solar-panel windows could be next for your ... to recent quantum-dot work by Los Alamos National ... and guided towards the slab edge equipped with a solar cell. ...

  9. NREL and Partners Demonstrate Quantum Dots that Assemble Themselves - News

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Releases | NREL and Partners Demonstrate Quantum Dots that Assemble Themselves Surprising breakthrough could bolster quantum photonics, solar cell efficiency February 8, 2013 Scientists from the U.S. Department of Energy's National Renewable Energy Laboratory and other labs have demonstrated a process whereby quantum dots can self-assemble at optimal locations in nanowires, a breakthrough that could improve solar cells, quantum computing, and lighting devices. A paper on the new technology,

  10. Metal Halide Surface Treatment of Quantum Dots - Energy Innovation Portal

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Advanced Materials Advanced Materials Find More Like This Return to Search Metal Halide Surface Treatment of Quantum Dots National Renewable Energy Laboratory Contact NREL About This Technology Technology Marketing Summary Quantum dot (QD) solids are a solution-processed, composite thin film semiconductor system that is being developed for optoelectronics (display technology, solid state lighting, next generation photovoltaics, photodetector application, etc.). For photovoltaics, in addition to

  11. Deformation potentials of CdSe quantum dots

    SciTech Connect

    Li, Jingbo; Wang, Lin-Wang

    2004-06-02

    The size dependent deformation potentials of CdSe quantum dots are studied by first principle and semi-empirical pseudopotentials calculations. They find that the amplitude of the quantum dot deformation potential is only slightly larger than the bulk value, and this increase is mostly caused by the off {Lambda} point deformation potentials in the bulk, which are larger in amplitude than the {Lambda} point deformation potential.

  12. Los Alamos Quantum Dots for Solar, Display Technology

    SciTech Connect

    Klimov, Victor

    2015-04-13

    Quantum dots are ultra-small bits of semiconductor matter that can be synthesized with nearly atomic precision via modern methods of colloidal chemistry. Their emission color can be tuned by simply varying their dimensions. Color tunability is combined with high emission efficiencies approaching 100 percent. These properties have recently become the basis of a new technology – quantum dot displays – employed, for example, in the newest generation of e-readers and video monitors.

  13. Tunable Quantum Dot Solids: Impact of Interparticle Interactions on Bulk

    Office of Scientific and Technical Information (OSTI)

    Properties (Technical Report) | SciTech Connect Tunable Quantum Dot Solids: Impact of Interparticle Interactions on Bulk Properties Citation Details In-Document Search Title: Tunable Quantum Dot Solids: Impact of Interparticle Interactions on Bulk Properties QD-solids comprising self-assembled semiconductor nanocrystals such as CdSe are currently under investigation for use in a wide array of applications including light emitting diodes, solar cells, field effect transistors, photodetectors,

  14. Status report on the Small Secure Transportable Autonomous Reactor (SSTAR) /Lead-cooled Fast Reactor (LFR) and supporting research and development.

    SciTech Connect

    Sienicki, J. J.; Moisseytsev, A.; Yang, W. S.; Wade, D. C.; Nikiforova, A.; Hanania, P.; Ryu, H. J.; Kulesza, K. P.; Kim, S. J.; Halsey, W. G.; Smith, C. F.; Brown, N. W.; Greenspan, E.; de Caro, M.; Li, N.; Hosemann, P.; Zhang, J.; Yu, H.; Nuclear Engineering Division; LLNL; LANL; Massachusetts Inst. of Tech.; Ecole des Mines de Paris; Oregon State Univ.; Univ.of California at Berkley

    2008-06-23

    This report provides an update on development of a pre-conceptual design for the Small Secure Transportable Autonomous Reactor (SSTAR) Lead-Cooled Fast Reactor (LFR) plant concept and supporting research and development activities. SSTAR is a small, 20 MWe (45 MWt), natural circulation, fast reactor plant for international deployment concept incorporating proliferation resistance for deployment in non-fuel cycle states and developing nations, fissile self-sufficiency for efficient utilization of uranium resources, autonomous load following making it suitable for small or immature grid applications, and a high degree of passive safety further supporting deployment in developing nations. In FY 2006, improvements have been made at ANL to the pre-conceptual design of both the reactor system and the energy converter which incorporates a supercritical carbon dioxide Brayton cycle providing higher plant efficiency (44 %) and improved economic competitiveness. The supercritical CO2 Brayton cycle technology is also applicable to Sodium-Cooled Fast Reactors providing the same benefits. One key accomplishment has been the development of a control strategy for automatic control of the supercritical CO2 Brayton cycle in principle enabling autonomous load following over the full power range between nominal and essentially zero power. Under autonomous load following operation, the reactor core power adjusts itself to equal the heat removal from the reactor system to the power converter through the large reactivity feedback of the fast spectrum core without the need for motion of control rods, while the automatic control of the power converter matches the heat removal from the reactor to the grid load. The report includes early calculations for an international benchmarking problem for a LBE-cooled, nitride-fueled fast reactor core organized by the IAEA as part of a Coordinated Research Project on Small Reactors without Onsite Refueling; the calculations use the same neutronics

  15. New Research Projects > Research > The Energy Materials Center...

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    - Coates Research Initiative - Abrua Research Initiative - Schlom New Research Projects Transport Dynamics and Carbonation Tolerance in Solution Processable Ionomers: Enabling a...

  16. Magneto-optical absorption in semiconducting spherical quantum dots: Influence of the dot-size, confining potential, and magnetic field

    SciTech Connect

    Kushwaha, Manvir S.

    2014-12-15

    Semiconducting quantum dots – more fancifully dubbed artificial atoms – are quasi-zero dimensional, tiny, man-made systems with charge carriers completely confined in all three dimensions. The scientific quest behind the synthesis of quantum dots is to create and control future electronic and optical nanostructures engineered through tailoring size, shape, and composition. The complete confinement – or the lack of any degree of freedom for the electrons (and/or holes) – in quantum dots limits the exploration of spatially localized elementary excitations such as plasmons to direct rather than reciprocal space. Here we embark on a thorough investigation of the magneto-optical absorption in semiconducting spherical quantum dots characterized by a confining harmonic potential and an applied magnetic field in the symmetric gauge. This is done within the framework of Bohm-Pines’ random-phase approximation that enables us to derive and discuss the full Dyson equation that takes proper account of the Coulomb interactions. As an application of our theoretical strategy, we compute various single-particle and many-particle phenomena such as the Fock-Darwin spectrum; Fermi energy; magneto-optical transitions; probability distribution; and the magneto-optical absorption in the quantum dots. It is observed that the role of an applied magnetic field on the absorption spectrum is comparable to that of a confining potential. Increasing (decreasing) the strength of the magnetic field or the confining potential is found to be analogous to shrinking (expanding) the size of the quantum dots: resulting into a blue (red) shift in the absorption spectrum. The Fermi energy diminishes with both increasing magnetic-field and dot-size; and exhibits saw-tooth-like oscillations at large values of field or dot-size. Unlike laterally confined quantum dots, both (upper and lower) magneto-optical transitions survive even in the extreme instances. However, the intra-Landau level

  17. Steering microtubule shuttle transport with dynamically controlled magnetic fields

    DOE PAGES [OSTI]

    Mahajan, K. D.; Ruan, G.; Dorcéna, C. J.; Vieira, G.; Nabar, G.; Bouxsein, N. F.; Chalmers, J. J.; Bachand, G. D.; Sooryakumar, R.; Winter, J. O.

    2016-03-23

    Nanoscale control of matter is critical to the design of integrated nanosystems. Here, we describe a method to dynamically control directionality of microtubule (MT) motion using programmable magnetic fields. MTs are combined with magnetic quantum dots (i.e., MagDots) that are manipulated by external magnetic fields provided by magnetic nanowires. MT shuttles thus undergo both ATP-driven and externally-directed motion with a fluorescence component that permits simultaneous visualization of shuttle motion. This technology is used to alter the trajectory of MTs in motion and to pin MT motion. Ultimately, such an approach could be used to evaluate the MT-kinesin transport system andmore » could serve as the basis for improved lab-on-a-chip technologies based on MT transport.« less

  18. transportation-system-modeling-webinar

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Webinar Announcement Webinar for the Intelligent Transportation Society of the Midwest (ITS Midwest) May 16, 2011 1:00 PM(CST) Hubert Ley Director, TRACC Argonne National Laboratory Argonne, Illinois High Performance Computing in Transportation Research - High Fidelity Transportation Models and More The Role of High-Performance Computing Because ITS relies on a very diverse collection of technologies, including communication and control technologies, advanced computing, information management

  19. Sustainable Transportation | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)

    Home » Sustainable Transportation Sustainable Transportation Bioenergy Bioenergy Read more Hydrogen and Fuel Cells Hydrogen and Fuel Cells Read more Vehicles Vehicles Read more The Office of Energy Efficiency and Renewable Energy (EERE) leads U.S. researchers and other partners in making transportation cleaner and more efficient through solutions that put electric drive vehicles on the road and replace oil with clean domestic fuels. Through our Vehicle, Bioenergy, and Fuel Cell Technologies

  20. computational-hydraulics-for-transportation

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Transportation Workshop Sept. 23-24, 2009 Argonne TRACC Dr. Steven Lottes This email address is being protected from spambots. You need JavaScript enabled to view it. Announcement pdficon small The Transportation Research and Analysis Computing Center at Argonne National Laboratory will hold a workshop on the use of computational hydraulics for transportation applications. The goals of the workshop are: Bring together people who are using or would benefit from the use of high performance cluster

  1. Improving PbS Quantum Dot Solar Cell Power Conversion Efficiency to an NREL-Certified 4.4% (Fact Sheet)

    SciTech Connect

    Not Available

    2012-01-01

    Transition metal oxide improves overall efficiency and maintains performance with inexpensive metals. A research team at the National Renewable Energy Laboratory (NREL) has demonstrated that inserting a transition metal oxide (TMO) between the lead sulfide (PbS) quantum dot (QD) layer and the metal electrode eliminates the Schottky barrier that impedes efficient hole extraction and thereby improves the overall conversion efficiency. This allows for inexpensive metals such as Al to be employed without loss of performance. n-type TMOs consisting of molybdenum oxide (MoO{sub x}) and vanadium oxide (V{sub 2}O{sub x}) were used as an efficient hole extraction layer (HEL) in heterojunction ZnO/PbS QD solar cells. A 4.4% NREL-certified device was reported based on the MoO{sub x} HEL with Al as the back contact material, representing a more than 65% efficiency improvement compared with the case of Au contacting the PbS QD layer directly. The team finds the acting mechanism of the HEL to be a dipole formed at the MoO{sub x} and PbS interface, which enhances band bending to allow efficient hole extraction from the valence band of the PbS layer by MoO{sub x}. The carrier transport to the metal anode is likely enhanced through shallow gap states in the MoO{sub x} layer.

  2. Transportation Energy

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    ... Algae Raceway to speed path to biofuels News, Transportation Energy Algae Raceway to speed path to biofuels With the aim of transforming algae into a cost-competitive biofuel, ...

  3. Transportation Fuels

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Transportation Fuels DOE would invest $52 million to fund a major fleet transformation at Idaho National Laboratory, along with the installation of nine fuel management systems, purchase of additional flex fuel cars and one E85 ethanol fueling station. Transportation projects, such as the acquisition of highly efficient and alternative-fuel vehicles, are not authorized by ESPC legislation. DOE has twice proportion of medium vehicles and three times as many heavy vehicles as compared to the

  4. Transportation | NREL

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Transportation NREL's transportation infrastructure and programs are designed to significantly reduce petroleum use campus-wide. This infographic shows NREL's FY2015 fleet performance and fleet vehicle history compared to baseline FY 2005 and FY 2014. Petroleum fuel use decreased 28% from 2014 and increased 17% from baseline 2005. Alternative fuel use increased 53% from 2014 and increased 127% from baseline 2005. In baseline 2005, the fleet used 6,521 gasoline gallon equivalent (GGE) of E-85, in

  5. Effect of carrier dynamics and temperature on two-state lasing in semiconductor quantum dot lasers

    SciTech Connect

    Korenev, V. V. Savelyev, A. V.; Zhukov, A. E.; Omelchenko, A. V.; Maximov, M. V.

    2013-10-15

    It is analytically shown that the both the charge carrier dynamics in quantum dots and their capture into the quantum dots from the matrix material have a significant effect on two-state lasing phenomenon in quantum dot lasers. In particular, the consideration of desynchronization in electron and hole capture into quantum dots allows one to describe the quenching of ground-state lasing observed at high injection currents both qualitatevely and quantitatively. At the same time, an analysis of the charge carrier dynamics in a single quantum dot allowed us to describe the temperature dependences of the emission power via the ground- and excited-state optical transitions of quantum dots.

  6. Transportation and packaging resource guide

    SciTech Connect

    Arendt, J.W.; Gove, R.M.; Welch, M.J.

    1994-12-01

    The purpose of this resource guide is to provide a convenient reference document of information that may be useful to the U.S. Department of Energy (DOE) and DOE contractor personnel involved in packaging and transportation activities. An attempt has been made to present the terminology of DOE community usage as it currently exists. DOE`s mission is changing with emphasis on environmental cleanup. The terminology or nomenclature that has resulted from this expanded mission is included for the packaging and transportation user for reference purposes. Older terms still in use during the transition have been maintained. The Packaging and Transportation Resource Guide consists of four sections: Sect. 1, Introduction; Sect. 2, Abbreviations and Acronyms; Sect. 3, Definitions; and Sect. 4, References for packaging and transportation of hazardous materials and related activities, and Appendices A and B. Information has been collected from DOE Orders and DOE documents; U.S Department of Transportation (DOT), U.S. Environmental Protection Agency (EPA), and U.S. Nuclear Regulatory Commission (NRC) regulations; and International Atomic Energy Agency (IAEA) standards and other international documents. The definitions included in this guide may not always be a regulatory definition but are the more common DOE usage. In addition, the definitions vary among regulatory agencies. It is, therefore, suggested that if a definition is to be used in a regulatory or a legal compliance issue, the definition should be verified with the appropriate regulation. To assist in locating definitions in the regulations, a listing of all definition sections in the regulations are included in Appendix B. In many instances, the appropriate regulatory reference is indicated in the right-hand margin.

  7. Full counting statistics as a probe of quantum coherence in a side-coupled double quantum dot system

    SciTech Connect

    Xue, Hai-Bin

    2013-12-15

    We study theoretically the full counting statistics of electron transport through side-coupled double quantum dot (QD) based on an efficient particle-number-resolved master equation. It is demonstrated that the high-order cumulants of transport current are more sensitive to the quantum coherence than the average current, which can be used to probe the quantum coherence of the considered double QD system. Especially, quantum coherence plays a crucial role in determining whether the super-Poissonian noise occurs in the weak inter-dot hopping coupling regime depending on the corresponding QD-lead coupling, and the corresponding values of super-Poissonian noise can be relatively enhanced when considering the spins of conduction electrons. Moreover, this super-Poissonian noise bias range depends on the singly-occupied eigenstates of the system, which thus suggests a tunable super-Poissonian noise device. The occurrence-mechanism of super-Poissonian noise can be understood in terms of the interplay of quantum coherence and effective competition between fast-and-slow transport channels. -- Highlights: The FCS can be used to probe the quantum coherence of side-coupled double QD system. Probing quantum coherence using FCS may permit experimental tests in the near future. The current noise characteristics depend on the quantum coherence of this QD system. The super-Poissonian noise can be enhanced when considering conduction electron spin. The side-coupled double QD system suggests a tunable super-Poissonian noise device.

  8. UCSB researchers uncover fundamental limits on optical transparency in

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    conducting oxides | Center for Energy Efficient Materials researchers uncover fundamental limits on optical transparency in conducting oxides FOR IMMEDIATE RELEASE Contact information: Hartwin Peelaers, Materials Department, University of California, Santa Barbara, CA 93106-5050 peelaers [at] engineering [dot] ucsb [dot] edu UCSB researchers uncover fundamental limits on optical transparency in conducting oxides Santa Barbara, California, January 8, 2011 Conducting oxides are used as

  9. Suppression of dark current through barrier engineer for solution-processed colloidal quantum-dots infrared photodetectors

    SciTech Connect

    Jiang, Zhenyu E-mail: jianxu@engr.psu.edu; Liu, Yan; Mo, Chen; Wang, Li; Atalla, Mahmoud R. M.; Liu, Jie; Kurhade, Kandhar K.; Xu, Jian E-mail: jianxu@engr.psu.edu; Hu, Wenjia; Zhang, Wenjun; You, Guanjun; Zhang, Yu

    2015-08-31

    In an attempt to suppress the dark current, the barrier layer engineer for solution-processed PbSe colloidal quantum-dot (CQD) photodetectors has been investigated in the present study. It was found that the dark current can be significantly suppressed by implementing two types of carrier blocking layers, namely, hole blocking layer and electron blocking layer, sandwiched in between two active PbSe CQD layers. Meanwhile no adverse impact has been observed for the photo current. Our study suggests that this improvement resides on the transport pathway created via carrier recombination at intermediate layer, which provides wide implications for the suppression of dark current for infrared photodetectors.

  10. Single InAs quantum dot coupled to different 'environments' in one wafer for quantum photonics

    SciTech Connect

    Yu, Ying; Shang, Xiang-Jun; Li, Mi-Feng; Zha, Guo-Wei; Xu, Jian-Xing; Wang, Li-Juan; Wang, Guo-Wei; Ni, Hai-Qiao; Dou, Xiuming; Sun, Baoquan; Niu, Zhi-Chuan

    2013-05-20

    Self assembled small InAs quantum dots (SQDs) were formed in various densities and environments using gradient InAs deposition on a non-rotating GaAs substrate. Two SQD environments (SQD I and SQD II) were characterized. SQD I featured SQDs surrounded by large QDs, and SQD II featured individual SQDs in the wetting layer (WL). Micro-photoluminescence of single QDs embedded in a cavity under various excitation powers and electric fields gave insight into carrier transport processes. Potential fluctuations of the WL in SQD II, induced by charge redistribution, show promise for charge-tunable QD devices; SQD I shows higher luminescence intensity as a single-photon source.

  11. The impact of quantum dot filling on dual-band optical transitions via intermediate quantum states

    SciTech Connect

    Wu, Jiang; Passmore, Brandon; Manasreh, M. O.

    2015-08-28

    InAs/GaAs quantum dot infrared photodetectors with different doping levels were investigated to understand the effect of quantum dot filling on both intraband and interband optical transitions. The electron filling of self-assembled InAs quantum dots was varied by direct doping of quantum dots with different concentrations. Photoresponse in the near infrared and middle wavelength infrared spectral region was observed from samples with low quantum dot filling. Although undoped quantum dots were favored for interband transitions with the absence of a second optical excitation in the near infrared region, doped quantum dots were preferred to improve intraband transitions in the middle wavelength infrared region. As a result, partial filling of quantum dot was required, to the extent of maintaining a low dark current, to enhance the dual-band photoresponse through the confined electron states.

  12. R&D Magazine: Windows into Solar Power Sources with Quantum Dots

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    R&D Magazine: Windows into Solar Power Sources with Quantum Dots R&D Magazine: Windows into Solar Power Sources with Quantum Dots A luminescent solar concentrator is an emerging ...

  13. R&D Magazine: Windows into Solar Power Sources with Quantum Dots

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    R&D Magazine: Windows into Solar Power Sources with Quantum Dots August 30, 2015 R&D Magazine: Windows into Solar Power Sources with Quantum Dots A luminescent solar concentrator ...

  14. BA capped CdSe quantum dot sensitized solar cell (Conference...

    Office of Scientific and Technical Information (OSTI)

    BA capped CdSe quantum dot sensitized solar cell Citation Details In-Document Search Title: BA capped CdSe quantum dot sensitized solar cell Authors: Sykora, Milan 1 ; Koposov, ...

  15. CdSe Quantum-Dot-Sensitized Solar Cell with ~100% Internal Quantum...

    Office of Scientific and Technical Information (OSTI)

    CdSe Quantum-Dot-Sensitized Solar Cell with 100% Internal Quantum Efficiency Citation Details In-Document Search Title: CdSe Quantum-Dot-Sensitized Solar Cell with 100% Internal ...

  16. Overview of DOE - DOT December 2009 CNG and Hydrogen Fuels Workshop...

    Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)

    DOE - DOT December 2009 CNG and Hydrogen Fuels Workshop Overview of DOE - DOT December 2009 CNG and Hydrogen Fuels Workshop These slides were presented at the Onboard Storage Tank ...

  17. Thick-shell nanocrystal quantum dots (Patent) | SciTech Connect

    Office of Scientific and Technical Information (OSTI)

    Title: Thick-shell nanocrystal quantum dots Colloidal nanocrystal quantum dots comprising an inner core having an average diameter of at least 1.5 nm and an outer shell, where said ...

  18. PbSe Quantum Dot Solar Cells with More than 6% Efficiency Fabricated...

    Office of Scientific and Technical Information (OSTI)

    Journal Article: PbSe Quantum Dot Solar Cells with More than 6% Efficiency Fabricated in Ambient Atmosphere Citation Details In-Document Search Title: PbSe Quantum Dot Solar Cells ...

  19. Engineered CuInSexS2-x Quantum Dots for Sensitized Solar Cells...

    Office of Scientific and Technical Information (OSTI)

    Engineered CuInSexS2-x Quantum Dots for Sensitized Solar Cells Citation Details In-Document Search Title: Engineered CuInSexS2-x Quantum Dots for Sensitized Solar Cells Authors: ...

  20. Charge Generation in PbS Quantum Dot Solar Cells Characterized...

    Office of Scientific and Technical Information (OSTI)

    Dot Solar Cells Characterized by Temperature-Dependent Steady-State Photoluminescence Citation Details In-Document Search Title: Charge Generation in PbS Quantum Dot Solar Cells ...

  1. Surface Induced Magnetism in Quantum Dots

    SciTech Connect

    Meulenberg, R W; Lee, J I

    2009-08-20

    The study of nanometer sized semiconductor crystallites, also known as quantum dots (QDs), has seen rapid advancements in recent years in scientific disciplines ranging from chemistry, physics, biology, materials science, and engineering. QD materials of CdSe, ZnSe, InP, as well as many others, can be prepared in the size range of 1-10 nm producing uniform, nearly monodisperse materials that are typically coated with organic molecules [1-3]. The strength of charge carrier confinement, which dictates the size-dependent properties, in these QDs depends on the nature of the material and can be correlated to the Bohr radius for the system of interest. For instance, the Bohr radius for CdSe is {approx} 5 nm, while in the more covalent structure of InP, the Bohr radius approaches {approx} 10 nm. The study of CdSe QDs has been particularly extensive during the last decade because they exhibit unique and tunable optical properties and are readily synthesized with high-crystallinity and narrow size dispersions. Although the core electronic properties of CdSe are explained in terms of the quantum confinement model, experimental efforts to elucidate the surface structure of these materials have been limited. Typically, colloidal CdSe QDs are coated with an organic surfactant, which typically consists of an organo-phosphine, -thiol, or -amine, that has the function of energetically relaxing defect states via coordination to partially coordinated surface atoms. The organic surfactant also acts to enhance carrier confinement and prevent agglomeration of the particles. Chemically, it has been shown that the bonding of the surfactant to the CdSe QD occurs through Cd atoms resulting cleavage of the Se atoms and formation of a Cd-rich (i.e. non-stoichiometric) particle [5].

  2. Energy levels of double triangular graphene quantum dots

    SciTech Connect

    Liang, F. X.; Jiang, Z. T. Zhang, H. Y.; Li, S.; Lv, Z. T.

    2014-09-28

    We investigate theoretically the energy levels of the coupled double triangular graphene quantum dots (GQDs) based on the tight-binding Hamiltonian model. The double GQDs including the ZZ-type, ZA-type, and AA-type GQDs with the two GQDs having the zigzag or armchair boundaries can be coupled together via different interdot connections, such as the direct coupling, the chains of benzene rings, and those of carbon atoms. It is shown that the energy spectrum of the coupled double GQDs is the amalgamation of those spectra of the corresponding two isolated GQDs with the modification triggered by the interdot connections. The interdot connection is inclined to lift up the degeneracies of the energy levels in different degree, and as the connection changes from the direct coupling to the long chains, the removal of energy degeneracies is suppressed in ZZ-type and AA-type double GQDs, which indicates that the two coupled GQDs are inclined to become decoupled. Then we consider the influences on the spectra of the coupled double GQDs induced by the electric fields applied on the GQDs or the connection, which manifests as the global spectrum redistribution or the local energy level shift. Finally, we study the symmetrical and asymmetrical energy spectra of the double GQDs caused by the substrates supporting the two GQDs, clearly demonstrating how the substrates affect the double GQDs' spectrum. This research elucidates the energy spectra of the coupled double GQDs, as well as the mechanics of manipulating them by the electric field and the substrates, which would be a significant reference for designing GQD-based devices.

  3. Nonradiative recombination of excitons in semimagnetic quantum dots

    SciTech Connect

    Chernenko, A. V.

    2015-12-15

    The mechanisms of the nonradiative recombination of excitons in neutral and charged quantum dots based on II–VI semimagnetic semiconductors are investigated. It is shown that, along with the dipole–dipole and direct-exchange mechanisms, there is one more mechanism referred to as the indirect-exchange mechanism and related to sp–d mixing. The selection rules for nonradiative recombination by exchange mechanisms are subsequently derived. The dependence of the efficiency of all recombination mechanisms on the quantum-dot size is studied. The experimentally observed growth in the intracenter photoluminescence intensity with decreasing size of dots and nanocrystals is accounted for. Methods for experimental determination of the contributions of different mechanisms to nonradiative recombination are discussed.

  4. Quasi-periodic quantum dot arrays produced by electrochemical synthesis

    SciTech Connect

    Bandyopadhyay, S.; Miller, A.E.; Yue, D.F.; Banerjee, G.; Ricker, R.E.; Jones, S.; Eastman, J.A.; Baugher, E.; Chandrasekhar, M.

    1994-06-01

    We discuss a ``gentle`` electrochemical technique for fabricating quasi-periodic quantum dot arrays. The technique exploits a self-organizing phenomenon to produce quasi-periodic arrangement of dots and provides excellent control over dot size and interdot spacing. Unlike conventional nanolithography, it does not cause radiation damage to the structures during exposure to pattern delineating beams (e-beam, ion-beam or x-ray). Moreover, it does not require harsh processing steps like reactive ion etching, offers a minimum feature size of {approximately}40 {angstrom}, allows the fabrication of structures on nonplanar surfaces (e.g. spherical or cylindrical substrates), is amenable to mass production (millions of wafers can be processed simultaneously) and is potentially orders of magnitude cheaper than conventional nanofabrication. In this paper, we describe our initial results and show the promise of this technique for low-cost and high-yield nanosynthesis.

  5. Transportation Energy Futures Analysis Snapshot

    Energy.gov [DOE]

    Transportation currently accounts for 71% of total U.S. petroleum use and 33% of the nation's total carbon emissions. The TEF project explores how combining multiple strategies could reduce GHG emissions and petroleum use by 80%. Researchers examined four key areas – lightduty vehicles, non-light-duty vehicles, fuels, and transportation demand – in the context of the marketplace, consumer behavior, industry capabilities, technology and the energy and transportation infrastructure. The TEF reports support DOE long-term planning. The reports provide analysis to inform decisions about transportation energy research investments, as well as the role of advanced transportation energy technologies and systems in the development of new physical, strategic, and policy alternatives.

  6. International Conference on Surface Transportation System Resilience...

    Energy.gov [DOE] (indexed site)

    practices and state of the art research results on how to adapt surface transportation networks to the potential impacts of climate change and extreme weather events. Learn More......

  7. Self-organized formation of quantum dots of a material on a substrate

    DOEpatents

    Zhang, Zhenyu; Wendelken, John F.; Chang, Ming-Che; Pai, Woei Wu

    2001-01-01

    Systems and methods are described for fabricating arrays of quantum dots. A method for making a quantum dot device, includes: forming clusters of atoms on a substrate; and charging the clusters of atoms such that the clusters of atoms repel one another. The systems and methods provide advantages because the quantum dots can be ordered with regard to spacing and/or size.

  8. Analysis of the efficiency of intermediate band solar cells based on quantum dot supercrystals

    SciTech Connect

    Heshmati, S; Golmohammadi, S; Abedi, K; Taleb, H

    2014-03-28

    We have studied the influence of the quantum-dot (QD) width and the quantum-dot conduction band (QD-CB) offset on the efficiency of quantum-dot intermediate band solar cells (QD-IBSCs). Simulation results demonstrate that with increasing QD-CB offset and decreasing QD width, the maximum efficiency is achieved. (laser applications and other topics in quantum electronics)

  9. Quantum-dot based nanothermometry in optical plasmonic recording media

    SciTech Connect

    Maestro, Laura Martinez; Zhang, Qiming; Li, Xiangping; Gu, Min; Jaque, Daniel

    2014-11-03

    We report on the direct experimental determination of the temperature increment caused by laser irradiation in a optical recording media constituted by a polymeric film in which gold nanorods have been incorporated. The incorporation of CdSe quantum dots in the recording media allowed for single beam thermal reading of the on-focus temperature from a simple analysis of the two-photon excited fluorescence of quantum dots. Experimental results have been compared with numerical simulations revealing an excellent agreement and opening a promising avenue for further understanding and optimization of optical writing processes and media.

  10. Optical control of the emission direction of a quantum dot

    SciTech Connect

    Luxmoore, I. J.; Wasley, N. A.; Fox, A. M.; Skolnick, M. S.; Ramsay, A. J.; Thijssen, A. C. T.; Oulton, R.; Hugues, M.; CNRS-CRHEA, rue Bernard Grgory, 06560 Valbonne

    2013-12-09

    Using the helicity of a non-resonant excitation laser, control over the emission direction of an InAs/GaAs quantum dot is demonstrated. The quantum dot is located off-center in a crossed-waveguide structure, such that photons of opposite circular polarization are emitted into opposite waveguide directions. By preferentially exciting spin-polarized excitons, the direction of emission can therefore be controlled. The directional control is quantified by using the ratio of the intensity of the light coupled into the two waveguides, which reaches a maximum of 35%.

  11. CNEEC - Research Projects

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    ... recent successes in CNEEC on making and understanding quantum dot structures, including observing for the first time shape-induced bandgap variations in individual quantum dots. ...

  12. Fast gain and phase recovery of semiconductor optical amplifiers based on submonolayer quantum dots

    SciTech Connect

    Herzog, Bastian Owschimikow, Nina; Kaptan, Yücel; Kolarczik, Mirco; Switaiski, Thomas; Woggon, Ulrike; Schulze, Jan-Hindrik; Rosales, Ricardo; Strittmatter, André; Bimberg, Dieter; Pohl, Udo W.

    2015-11-16

    Submonolayer quantum dots as active medium in opto-electronic devices promise to combine the high density of states of quantum wells with the fast recovery dynamics of self-assembled quantum dots. We investigate the gain and phase recovery dynamics of a semiconductor optical amplifier based on InAs submonolayer quantum dots in the regime of linear operation by one- and two-color heterodyne pump-probe spectroscopy. We find an as fast recovery dynamics as for quantum dot-in-a-well structures, reaching 2 ps at moderate injection currents. The effective quantum well embedding the submonolayer quantum dots acts as a fast and efficient carrier reservoir.

  13. Few-hole double quantum dot in an undoped GaAs/AlGaAs heterostructure

    SciTech Connect

    Tracy, L. A.; Hargett, T. W.; Reno, J. L.

    2014-03-24

    We demonstrate a hole double quantum dot in an undoped GaAs/AlGaAs heterostructure. The interdot coupling can be tuned over a wide range, from formation of a large single dot to two well-isolated quantum dots. Using charge sensing, we show the ability to completely empty the dot of holes and control the charge occupation in the few-hole regime. The device should allow for control of individual hole spins in single and double quantum dots in GaAs.

  14. Increased InAs quantum dot size and density using bismuth as a surfactant

    SciTech Connect

    Dasika, Vaishno D.; Krivoy, E. M.; Nair, H. P.; Maddox, S. J.; Park, K. W.; Yu, E. T.; Bank, S. R.; Jung, D.; Lee, M. L.

    2014-12-22

    We have investigated the growth of self-assembled InAs quantum dots using bismuth as a surfactant to control the dot size and density. We find that the bismuth surfactant increases the quantum dot density, size, and uniformity, enabling the extension of the emission wavelength with increasing InAs deposition without a concomitant reduction in dot density. We show that these effects are due to bismuth acting as a reactive surfactant to kinetically suppress the surface adatom mobility. This mechanism for controlling quantum dot density and size has the potential to extend the operating wavelength and enhance the performance of various optoelectronic devices.

  15. Structure of droplet-epitaxy-grown InAs/GaAs quantum dots

    SciTech Connect

    Cohen, Eyal; Yochelis, Shira; Westreich, Ohad; Shusterman, Sergey; Kumah, Divine P.; Clarke, Roy; Yacoby, Yizhak; Paltiel, Yossi

    2011-09-06

    We have used a direct x-ray phasing method, coherent Bragg rod analysis, to obtain sub-angstrom resolution electron density maps of the InAs/GaAs dot system. The dots were grown by the droplet heteroepitaxy (DHE) technique and their structural and compositional properties are compared with those of dots grown by the strain-driven Stranski-Krastanov method. Our results show that the Ga diffusion into the DHE-grown dots is somewhat larger; however, other characteristics such as the composition of the dots uppermost layers, the interlayer spacing, and the bowing of the atomic layers are similar.

  16. An evaluation of Department of Transportation specification packages

    SciTech Connect

    Ratledge, J.E.; Rawl, R.R.

    1992-01-01

    Specification packages are broad families of package designs developed and authorized by the US Department of Transportation (DOT) and the Nuclear Regulatory Commission (NRC) for transport of certain Type B and fissile radioactive materials, with each specification containing a number of designs of various sizes. The specification package designs have remained essentially unchanged in a changing regulatory environment. Changes to package designs or authorized contents under the DOT system can be accomplished by rule making action, but there has been little updating of the designs over the years. Many of the individual package designs are no longer supported by reasonably current safety analyses. Since the publication of these specifications, there have been changes in regulatory requirements and improvements in methods of testing and analysis. Additionally, contemplated revisions to the DOT and NRC regulations to bring design requirements into accord with IAEA Safety Series No. 6, 1985 Edition would eliminate fissile classes and require resistance to a crush test for small Type B packages meeting certain criteria. The NRC has requested that the Oak Ridge National Laboratory (ORNL) staff review the safety documentation of the specification packages to determine the possible need for further testing and analysis, modifications to the designs, and, perhaps, elimination of any designs for which there is insufficient demonstration of compliance with current and proposed requirements. This paper will present a summary of the technical data and information concerning the use of the packages that has been received to date.

  17. An evaluation of Department of Transportation specification packages

    SciTech Connect

    Ratledge, J.E.; Rawl, R.R.

    1992-11-01

    Specification packages are broad families of package designs developed and authorized by the US Department of Transportation (DOT) and the Nuclear Regulatory Commission (NRC) for transport of certain Type B and fissile radioactive materials, with each specification containing a number of designs of various sizes. The specification package designs have remained essentially unchanged in a changing regulatory environment. Changes to package designs or authorized contents under the DOT system can be accomplished by rule making action, but there has been little updating of the designs over the years. Many of the individual package designs are no longer supported by reasonably current safety analyses. Since the publication of these specifications, there have been changes in regulatory requirements and improvements in methods of testing and analysis. Additionally, contemplated revisions to the DOT and NRC regulations to bring design requirements into accord with IAEA Safety Series No. 6, 1985 Edition would eliminate fissile classes and require resistance to a crush test for small Type B packages meeting certain criteria. The NRC has requested that the Oak Ridge National Laboratory (ORNL) staff review the safety documentation of the specification packages to determine the possible need for further testing and analysis, modifications to the designs, and, perhaps, elimination of any designs for which there is insufficient demonstration of compliance with current and proposed requirements. This paper will present a summary of the technical data and information concerning the use of the packages that has been received to date.

  18. Transportation Safety

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    and Application Center for Hydrogen Energy Research Programs ARPA-E Basic Energy Sciences ... Sea State Contour) Code Online Abstracts and Reports Water Power Personnel ...

  19. Research Highlight

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Arctic Haze: Effect of Anthropogenic and Biomass Burning Aerosols Transported from Europe to the Arctic Download a printable PDF Submitter: Fast, J. D., Pacific Northwest National Laboratory Area of Research: Aerosol Properties Working Group(s): Cloud-Aerosol-Precipitation Interactions Journal Reference: Marelle L, J Raut, JL Thomas, KS Law, B Quennehen, G Ancellet, J Pelon, A Schwarzenboeck, and JD Fast. 2015. "Transport of anthropogenic and biomass burning aerosols from Europe to the

  20. Height control of self-assembled quantum dots by strain engineering during capping

    SciTech Connect

    Grossi, D. F. Koenraad, P. M.; Smereka, P.; Keizer, J. G.; Ulloa, J. M.

    2014-10-06

    Strain engineering during the capping of III-V quantum dots has been explored as a means to control the height of strained self-assembled quantum dots. Results of Kinetic Monte Carlo simulations are confronted with cross-sectional Scanning Tunnel Microscopy (STM) measurements performed on InAs quantum dots grown by molecular beam epitaxy. We studied InAs quantum dots that are capped by In{sub x}Ga{sub (1−x)}As layers of different indium compositions. Both from our realistic 3D kinetic Monte Carlo simulations and the X-STM measurements on real samples, a trend in the height of the capped quantum dot is found as a function of the lattice mismatch between the quantum dot material and the capping layer. Results obtained on additional material combinations show a generic role of the elastic energy in the control of the quantum dot morphology by strain engineering during capping.

  1. Suppression of low-frequency charge noise in gates-defined GaAs quantum dots

    SciTech Connect

    You, Jie; Li, Hai-Ou E-mail: gpguo@ustc.edu.cn; Wang, Ke; Cao, Gang; Song, Xiang-Xiang; Xiao, Ming; Guo, Guo-Ping E-mail: gpguo@ustc.edu.cn

    2015-12-07

    To reduce the charge noise of a modulation-doped GaAs/AlGaAs quantum dot, we have fabricated shallow-etched GaAs/AlGaAs quantum dots using the wet-etching method to study the effects of two-dimensional electron gas (2DEG) underneath the metallic gates. The low-frequency 1/f noise in the Coulomb blockade region of the shallow-etched quantum dot is compared with a non-etched quantum dot on the same wafer. The average values of the gate noise are approximately 0.5 μeV in the shallow-etched quantum dot and 3 μeV in the regular quantum dot. Our results show the quantum dot low-frequency charge noise can be suppressed by the removal of the 2DEG underneath the metallic gates, which provides an architecture for noise reduction.

  2. Intermediate-band photosensitive device with quantum dots having tunneling barrier embedded in organic matrix

    DOEpatents

    Forrest, Stephen R.

    2008-08-19

    A plurality of quantum dots each have a shell. The quantum dots are embedded in an organic matrix. At least the quantum dots and the organic matrix are photoconductive semiconductors. The shell of each quantum dot is arranged as a tunneling barrier to require a charge carrier (an electron or a hole) at a base of the tunneling barrier in the organic matrix to perform quantum mechanical tunneling to reach the respective quantum dot. A first quantum state in each quantum dot is between a lowest unoccupied molecular orbital (LUMO) and a highest occupied molecular orbital (HOMO) of the organic matrix. Wave functions of the first quantum state of the plurality of quantum dots may overlap to form an intermediate band.

  3. Magnetic field induced quantum dot brightening in liquid crystal synergized magnetic and semiconducting nanoparticle composite assemblies

    DOE PAGES [OSTI]

    Amaral, Jose Jussi; Wan, Jacky; Rodarte, Andrea L.; Ferri, Christopher; Quint, Makiko T.; Pandolfi, Ronald J.; Scheibner, Michael; Hirst, Linda S.; Ghosh, Sayantani

    2014-10-22

    The design and development of multifunctional composite materials from artificial nano-constituents is one of the most compelling current research areas. This drive to improve over nature and produce ‘meta-materials’ has met with some success, but results have proven limited with regards to both the demonstration of synergistic functionalities and in the ability to manipulate the material properties post-fabrication and in situ. Here, magnetic nanoparticles (MNPs) and semiconducting quantum dots (QDs) are co-assembled in a nematic liquid crystalline (LC) matrix, forming composite structures in which the emission intensity of the quantum dots is systematically and reversibly controlled with a small appliedmore » magnetic field (<100 mT). This magnetic field-driven brightening, ranging between a two- to three-fold peak intensity increase, is a truly cooperative effect: the LC phase transition creates the co-assemblies, the clustering of the MNPs produces LC re-orientation at atypical low external field, and this re-arrangement produces compaction of the clusters, resulting in the detection of increased QD emission. These results demonstrate a synergistic, reversible, and an all-optical process to detect magnetic fields and additionally, as the clusters are self-assembled in a fluid medium, they offer the possibility for these sensors to be used in broad ranging fluid-based applications.« less

  4. Magnetic field induced quantum dot brightening in liquid crystal synergized magnetic and semiconducting nanoparticle composite assemblies

    SciTech Connect

    Amaral, Jose Jussi; Wan, Jacky; Rodarte, Andrea L.; Ferri, Christopher; Quint, Makiko T.; Pandolfi, Ronald J.; Scheibner, Michael; Hirst, Linda S.; Ghosh, Sayantani

    2014-10-22

    The design and development of multifunctional composite materials from artificial nano-constituents is one of the most compelling current research areas. This drive to improve over nature and produce meta-materials has met with some success, but results have proven limited with regards to both the demonstration of synergistic functionalities and in the ability to manipulate the material properties post-fabrication and in situ. Here, magnetic nanoparticles (MNPs) and semiconducting quantum dots (QDs) are co-assembled in a nematic liquid crystalline (LC) matrix, forming composite structures in which the emission intensity of the quantum dots is systematically and reversibly controlled with a small applied magnetic field (<100 mT). This magnetic field-driven brightening, ranging between a two- to three-fold peak intensity increase, is a truly cooperative effect: the LC phase transition creates the co-assemblies, the clustering of the MNPs produces LC re-orientation at atypical low external field, and this re-arrangement produces compaction of the clusters, resulting in the detection of increased QD emission. These results demonstrate a synergistic, reversible, and an all-optical process to detect magnetic fields and additionally, as the clusters are self-assembled in a fluid medium, they offer the possibility for these sensors to be used in broad ranging fluid-based applications.

  5. Nanocrystal quantum dots: building blocks for tunable optical amplifiers and lasers

    SciTech Connect

    Mikhailovsky, A. A.; Malko, A. V.; Klimov, V. I.; Leatherdale, C. A.; Eisler, H-J.; Bawendi, M.; Hollingsworth, J. A.

    2001-01-01

    We study optical processes relevant to optical amplification and lasing in CdSe nanocrystal quantum dots (NQD). NQDs are freestanding nanoparticles prepared using solution-based organometallic reactions originally developed for the Cd chalcogenides, CdS, CdSe and CdTe [J. Am. Chem. Soc. 115, 8706 (1993)]. We investigate NQDs with diameters ranging from 2 to 8 nm. Due to strong quantum confinement, they exhibit size-dependent spectral tunability over an energy range as wide as several hundred meV. We observe a strong effect of the matrix/solvent on optical gain properties of CdSe NQDs. In most of the commonly used solvents (such as hexane and toluene), gain is suppressed due to strong photoinduced absorption associated with carriers trapped at solvent-related interface states. In contrast, matrix-free close packed NQD films (NQD solids) exhibit large optical gain with a magnitude that is sufficiently high for the optical gain to successfully compete with multiparticle Auger recombination [Science 287, 10117 (2000)]. These films exhibit narrowband stimulated emission at both cryogenic and room temperature, and the emission color is tunable with dot size [Science 290, 314 (2000)]. Moreover, the NQD films can be incorporated into microcavities of different geometries (micro-spheres, wires, tubes) that produce lasing in whispering gallery modes. The facile preparation, chemical flexibility and wide-range spectral tunability due to strong quantum confinement are the key advantages that should motivate research into NQD applications in optical amplifiers and lasers.

  6. Revolutionary Method for Increasing the Efficiency of White Light Quantum Dot LEDs

    SciTech Connect

    Duty, Chad E [ORNL; Bennett, Charlee J C [ORNL; Sabau, Adrian S [ORNL; Jellison Jr, Gerald Earle [ORNL; Boudreaux, Philip R [ORNL; Walker, Steven C [ORNL; Ott, Ronald D [ORNL

    2011-01-01

    Covering a light-emitting diode (LED) with quantum dots (QDs) can produce a broad spectrum of white light. However, current techniques for applying QDs to LEDs suffer from a high density of defects and a non-uniform distribution of QDs, which respec-tively diminish the efficiency and quality of emitted light. Oak Ridge National Laboratory (ORNL) has the unique capability to thermally anneal QD structures at extremely high power densities for very short durations. This process, called pulse thermal proc-essing (PTP), reduces the number of point defects while main-taining the size and shape of the original QD nanostructure. Therefore, the efficiency of the QD wavelength conversion layer is improved without altering the emission spectrum defined by the size distribution of the quantum dot nanoparticles. The cur-rent research uses a thermal model to predict annealing tempera-tures during PTP and demonstrates up to a 300% increase in pho-toluminescence for QDs on passive substrates

  7. Development of an analysis capability for the National Transportation System

    SciTech Connect

    Anson, D.; Nelson, R.

    1997-10-24

    The purpose of this report is to examine the Department of Transportation`s (DOT) National Transportation System (NTS) initiative, to document what has been learned, and to outline a National Transportation Network Analysis Capability (NTNAC) based on a ``TRANSIMS-like`` approach. This study was conducted over a two month period at the end of FY1997. The scope of the effort was carefully defined to accommodate the short time horizon and to provide focus to a very large analytical problem. The objectives were to: (1) define the NTS and the NTS problem; (2) identify problem characteristics; (3) describe an analytical solution based on the TRANSIMS approach; (4) identify data requirements and availability; (5) develop criteria for a scenario to be used in a prototype demonstration; and (6) select a scenario for the prototype demonstration.

  8. Sustainable Transportation Success Stories | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)

    Sustainable Transportation Success Stories Sustainable Transportation Success Stories Sustainable Transportation Success Stories The Office of Energy Efficiency and Renewable Energy's (EERE) successes in converting tax dollars into sustainable transportation solutions are important steps in the drive toward cleaner vehicles for all purposes. Learn how EERE's investments in bioenergy, hydrogen and fuel cell research, and vehicle technologies are putting electric drive vehicles on the road and

  9. Transportation Infrastructure

    Office of Environmental Management (EM)

    09 Archive Transportation Fact of the Week - 2009 Archive #603 Where Does Lithium Come From? December 28, 2009 #602 Freight Statistics by Mode, 2007 Commodity Flow Survey December 21, 2009 #601 World Motor Vehicle Production December 14, 2009 #600 China Produced More Vehicles than the U.S. in 2008 December 7, 2009 #599 Historical Trend for Light Vehicle Sales November 30, 2009 #598 Hybrid Vehicle Sales by Model November 23, 2009 #597 Median Age of Cars and Trucks Rising in 2008 November 16, 2009

  10. NREL: Biomass Research - Capabilities

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    is then separated, purified, and recovered for use as a transportation fuel. NREL biomass researchers and scientists have strong capabilities in many facets of biomass...

  11. NETL Research Capabilities

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    ... of high-pressure, high-temperature hydrogen permeation testing. Researchers using the Advanced High Temperature, High-Pressure Transport Reactor have demonstrated acceptable ...

  12. InGaAs/GaAs (110) quantum dot formation via step meandering

    SciTech Connect

    Diez-Merino, Laura; Tejedor, Paloma

    2011-07-01

    InGaAs (110) semiconductor quantum dots (QDs) offer very promising prospects as a material base for a new generation of high-speed spintronic devices, such as single electron transistors for quantum computing. However, the spontaneous formation of InGaAs QDs is prevented by two-dimensional (2D) layer-by-layer growth on singular GaAs (110) substrates. In this work we have studied, by using atomic force microscopy and photoluminescence spectroscopy (PL), the growth of InGaAs/GaAs QDs on GaAs (110) stepped substrates by molecular beam epitaxy (MBE), and the modification of the adatom incorporation kinetics to surface steps in the presence of chemisorbed atomic hydrogen. The as-grown QDs exhibit lateral dimensions below 100 nm and emission peaks in the 1.35-1.37 eV range. It has been found that a step meandering instability derived from the preferential attachment of In adatoms to [110]-step edges relative to [11n]-type steps plays a key role in the destabilization of 2D growth that leads to 3D mound formation on both conventional and H-terminated vicinal substrates. In the latter case, the driving force for 3D growth via step meandering is enhanced by H-induced upward mass transport in addition to the lower energy cost associated with island formation on H-terminated substrates, which results in a high density array of InGaAs/GaAs dots selectively nucleated on the terrace apices with reduced lateral dimensions and improved PL efficiency relative to those of conventional MBE-grown samples.

  13. Quantitative Imaging and In Situ Concentration Measurements of Quantum Dot Nanomaterials in Variably Saturated Porous Media

    DOE PAGES [OSTI]

    Uyuşur, Burcu; Snee, Preston T.; Li, Chunyan; Darnault, Christophe J. G.

    2016-01-01

    Knowledge of the fate and transport of nanoparticles in the subsurface environment is limited, as techniques to monitor and visualize the transport and distribution of nanoparticles in porous media and measure their in situ concentrations are lacking. To address these issues, we have developed a light transmission and fluorescence method to visualize and measure in situ concentrations of quantum dot (QD) nanoparticles in variably saturated environments. Calibration cells filled with sand as porous medium and various known water saturation levels and QD concentrations were prepared. By measuring the intensity of the light transmitted through porous media exposed to fluorescent lightmore » and by measuring the hue of the light emitted by the QDs under UV light exposure, we obtained simultaneously in situ measurements of water saturation and QD nanoparticle concentrations with high spatial and temporal resolutions. Water saturation was directly proportional to the light intensity. A linear relationship was observed between hue-intensity ratio values and QD concentrations for constant water saturation levels. The advantages and limitations of the light transmission and fluorescence method as well as its implications for visualizing and measuring in situ concentrations of QDs nanoparticles in the subsurface environment are discussed.« less

  14. Panel 4 - applications to transportation

    SciTech Connect

    Nichols, F.; Au, J.; Bhattacharya, R.; Bhushan, B.; Blunier, D.; Boardman, B.; Brombolich, L.; Davidson, J.; Graham, M.; Hakim, N.; Harris, K.; Hay, R.; Herk, L.; Hojnacki, H.; Rourk, D.; Kamo, R.; Nieman, B.; O`Neill, D.; Peterson, M.B.; Pfaffenberger, G.; Pryor, R.W.; Russell, J.; Syniuta, W.; Tamor, M.; Vojnovich, T.; Yarbrough, W.; Yust, C.S.

    1993-01-01

    The aim of this group was to compile a listing of current and anticipated future problem areas in the transportation industry where the properties of diamond and DLC films make them especially attractive and where the panel could strongly endorse the establishment of DOE/Transportation Industry cooperative research efforts. This section identifies the problem areas for possible applications of diamond/DLC technology and presents indications of current approaches to these problems.

  15. transportation-systems-modeling-training

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Training Table of Contents Date Location Integrated Transportation Models Workshop at ITM 2012 April 29, 2012 Hyatt Regency Tampa, FL TRANSIMS Training Course April 14-15, 2011 James E. Clyburn University Transportation Center Orangeburg, SC TRANSIMS RTSTEP Guest Lecturer March 29, 2011 Argonne TRACC Argonne, IL TRANSIMS Training Course January 19-21 2011 Argonne TRACC Argonne, IL TRANSIMS Training Course September 7-8, 2010 Turner Fairbank Highway Research Center Washington D.C. Network

  16. Fabrication and optical properties of multishell InAs quantum dots on GaAs nanowires

    SciTech Connect

    Yan, Xin; Zhang, Xia Li, Junshuai; Cui, Jiangong; Ren, Xiaomin

    2015-02-07

    Hybrid nanostructures combining nanowires with quantum dots promote the development of nanoelectronic and nanophotonic devices with integrated functionalities. In this work, we present a complex nanostructure with multishell quantum dots grown on nanowires. 1–4 shells of Stranski-Krastanov InAs quantum dots are grown on the sidewalls of GaAs nanowires by metal organic chemical vapor deposition. Different dot shells are separated by 8 nm GaAs spacer shells. With increasing the number of shells, the quantum dots become sparser and tend to align in one array, which is caused by the shrinkage of facets on which dots prefer to grow as well as the strain fields produced by the lower set of dots which influences the migration of In adatoms. The size of quantum dots increases with the increase of shell number due to enhanced strain fields coupling. The spectra of multishell dots exhibit multiwavelength emission, and each peak corresponds to a dot shell. This hybrid structure may serve as a promising element in nanowire intermediate band solar cells, infrared nanolasers, and photodetectors.

  17. FINAL REPORT: Adopting Biophysics Methods in Pursuit of Biogeophysical Research: Advancing the Measurement and Modeling of Electrical Signatures of Microbe-Mineral Transformations Impacting Contaminant Transport

    SciTech Connect

    PRODAN, CAMELIA; SLATER, LEE; NTARLAGIANNIS, DIMITRIOS

    2012-09-01

    This exploratory project involved laboratory experiments to investigate three hypotheses: (H1) Physics-based modeling of low-frequency dispersions (henceforth referred to as alpha) measured in broadband dielectric spectroscopy (DS) data can quantify pore-scale geometric changes impacting contaminant transport resulting from biomineralization; (H2) Physics-based modeling of high-frequency dispersions (henceforth referred to as beta) measured in broadband dielectric spectroscopy data can quantify rates of mineral growth in/on the cell wall; (H3) Application of this measurement and modeling approach can enhance geophysical interpretation of bioremediation experiments conducted at the RIFLE IFC by providing constraints on bioremediation efficiency (biomass concentration, mineral uptake within the cell wall, biomineralization rate). We tested H1 by performing DS measurements (alpha and beta range) on iron (Fe) particles of dimensions similar to microbial cells, dispersed within agar gels over a range of Fe concentrations. We have tested the ability of the physics-based modeling to predict volume concentrations of the Fe particles by assuming that the Fe particles are polarizable inclusions within an otherwise nonpolarizable medium. We evaluated the smallest volume concentration that can be detected with the DS method. Similar experiments and modeling have been performed on the sulfate-reducing bacteria D. vulgaris. Synchrotron x-ray absorption measurements were conducted to determine the local structure of biominerals coatings on D. vulgaris which were grown in the presence of different Fe concentrations. We imaged the mineral growth on cell wall using SEM. We used dielectric spectroscopy to differentiate between iron sulfide precipitates of biotic and abiotic nature. Biotic measurements were made on D. vulgaris bacteria grown in the presence of different concentrations of iron to form different thicknesses of iron sulfide precipitates around themselves and abiotic

  18. Adopting Biophysics Methods in Pursuit of Biogeophysical Research: Advancing the measurement and modeling of electrical signatures of microbe-mineral transformations impacting contaminant transport

    SciTech Connect

    Prodan, Camelia

    2013-06-14

    This exploratory project involved laboratory experiments to investigate three hypotheses: (H1) Physics-based modeling of low-frequency dispersions (henceforth referred to as alpha) measured in broadband dielectric spectroscopy (DS) data can quantify pore-scale geometric changes impacting contaminant transport resulting from biomineralization; (H2) Physics-based modeling of high-frequency dispersions (henceforth referred to as beta) measured in broadband dielectric spectroscopy data can quantify rates of mineral growth in/on the cell wall; (H3) Application of this measurement and modeling approach can enhance geophysical interpretation of bioremediation experiments conducted at the RIFLE IFC by providing constraints on bioremediation efficiency (biomass concentration, mineral uptake within the cell wall, biomineralization rate). We tested H1 by performing DS measurements (alpha and beta range) on iron (Fe) particles of dimensions similar to microbial cells, dispersed within agar gels over a range of Fe concentrations. We have tested the ability of the physics-based modeling to predict volume concentrations of the Fe particles by assuming that the Fe particles are polarizable inclusions within an otherwise nonpolarizable medium. We evaluated the smallest volume concentration that can be detected with the DS method. Similar experiments and modeling have been performed on the sulfate-reducing bacteria D. vulgaris. Synchrotron x-ray absorption measurements were conducted to determine the local structure of biominerals coatings on D. vulgaris which were grown in the presence of different Fe concentrations. We imaged the mineral growth on cell wall using SEM. We used dielectric spectroscopy to differentiate between iron sulfide precipitates of biotic and abiotic nature. Biotic measurements were made on D. vulgaris bacteria grown in the presence of different concentrations of iron to form different thicknesses of iron sulfide precipitates around themselves and abiotic

  19. ADVANCED CUTTINGS TRANSPORT STUDY

    SciTech Connect

    Stefan Miska; Troy Reed; Ergun Kuru

    2004-09-30

    The Advanced Cuttings Transport Study (ACTS) was a 5-year JIP project undertaken at the University of Tulsa (TU). The project was sponsored by the U.S. Department of Energy (DOE) and JIP member companies. The objectives of the project were: (1) to develop and construct a new research facility that would allow three-phase (gas, liquid and cuttings) flow experiments under ambient and EPET (elevated pressure and temperature) conditions, and at different angle of inclinations and drill pipe rotation speeds; (2) to conduct experiments and develop a data base for the industry and academia; and (3) to develop mechanistic models for optimization of drilling hydraulics and cuttings transport. This project consisted of research studies, flow loop construction and instrumentation development. Following a one-year period for basic flow loop construction, a proposal was submitted by TU to the DOE for a five-year project that was organized in such a manner as to provide a logical progression of research experiments as well as additions to the basic flow loop. The flow loop additions and improvements included: (1) elevated temperature capability; (2) two-phase (gas and liquid, foam etc.) capability; (3) cuttings injection and removal system; (4) drill pipe rotation system; and (5) drilling section elevation system. In parallel with the flow loop construction, hydraulics and cuttings transport studies were preformed using drilling foams and aerated muds. In addition, hydraulics and rheology of synthetic drilling fluids were investigated. The studies were performed under ambient and EPET conditions. The effects of temperature and pressure on the hydraulics and cuttings transport were investigated. Mechanistic models were developed to predict frictional pressure loss and cuttings transport in horizontal and near-horizontal configurations. Model predictions were compared with the measured data. Predominantly, model predictions show satisfactory agreements with the measured data. As a

  20. Simulation of quantum dots size and spacing effect for intermediate band solar cell application based on InAs quantum dots arrangement in GaAs

    SciTech Connect

    Hendra, P. I. B. Rahayu, F. Darma, Y.

    2014-03-24

    Intermediate band solar cell (IBSC) has become a promising technology in increasing solar cell efficiency. In this work we compare absorption coefficient profile between InAs quantum dots with GaAs bulk. We calculate the efficiency of GaAs bulk and GaAs doped with 2, 5, and 10 nm InAs quantum dot. Effective distances in quantum dot arrangement based on electron tunneling consideration were also calculated. We presented a simple calculation method with low computing power demand. Results showed that arrangement of quantum dot InAs in GaAs can increase solar cell efficiency from 23.9 % initially up to 60.4%. The effective distance between two quantum dots was found 2 nm in order to give adequate distance to prevent electron tunneling and wave functions overlap.

  1. Now Find U.S. Department of Transportation Information in Science.gov |

    Office of Scientific and Technical Information (OSTI)

    OSTI, US Dept of Energy Office of Scientific and Technical Information Find U.S. Department of Transportation Information in Science.gov Back to the OSTI News Listing for 2009 Hundreds of thousands of records and full-text documents from the U. S. Department of Transportation can now be found in Science.gov. This means that when you launch a search at the Science.gov gateway, your single query can find science information from 14 government agencies, including the DOT National Transportation

  2. Combinatorial theory of the semiclassical evaluation of transport moments II: Algorithmic approach for moment generating functions

    SciTech Connect

    Berkolaiko, G.; Kuipers, J.

    2013-12-15

    Electronic transport through chaotic quantum dots exhibits universal behaviour which can be understood through the semiclassical approximation. Within the approximation, calculation of transport moments reduces to codifying classical correlations between scattering trajectories. These can be represented as ribbon graphs and we develop an algorithmic combinatorial method to generate all such graphs with a given genus. This provides an expansion of the linear transport moments for systems both with and without time reversal symmetry. The computational implementation is then able to progress several orders further than previous semiclassical formulae as well as those derived from an asymptotic expansion of random matrix results. The patterns observed also suggest a general form for the higher orders.

  3. Advanced method for increasing the efficiency of white light quantum dot LEDs

    SciTech Connect

    Duty, Chad E [ORNL; Bennett, Charlee J C [ORNL; Sabau, Adrian S [ORNL; Jellison Jr, Gerald Earle [ORNL; Boudreaux, Philip R [ORNL; Walker, Steven C [ORNL; Ott, Ronald D [ORNL

    2011-01-01

    Covering a light-emitting diode (LED) with quantum dots (QDs) can produce a broad spectrum of white light. However, current techniques for applying QDs to LEDs suffer from a high density of defects and a non-uniform distribution of QDs, which, respectively, diminish the efficiency and quality of emitted light. Oak Ridge National Laboratory (ORNL) has the unique capability to thermally anneal QD structures at extremely high power densities for very short durations. This process, called pulse thermal processing (PTP), reduces the number of point defects while maintaining the size and shape of the original QD nanostructure. Therefore, the efficiency of the QD wavelength conversion layer is improved without altering the emission spectrum defined by the size distribution of theQD nanoparticles. The current research uses a thermal model to predict annealing temperatures during PTP and demonstrates up to a 300% increase in photoluminescence for QDs on passive substrates.

  4. Facile synthesis and photoluminescence mechanism of graphene quantum dots

    SciTech Connect

    Yang, Ping; Zhou, Ligang; Zhang, Shenli; Pan, Wei Shen, Wenzhong; Wan, Neng

    2014-12-28

    We report a facile hydrothermal synthesis of intrinsic fluorescent graphene quantum dots (GQDs) with two-dimensional morphology. This synthesis uses glucose, concentrate sulfuric acid, and deionized water as reagents. Concentrated sulfuric acid is found to play a key role in controlling the transformation of as-prepared hydrothermal products from amorphous carbon nanodots to well-crystallized GQDs. These GQDs show typical absorption characteristic for graphene, and have nearly excitation-independent ultraviolet and blue intrinsic emissions. Temperature-dependent PL measurements have demonstrated strong electron-electron scattering and electron-phonon interactions, suggesting a similar temperature behavior of GQDs to inorganic semiconductor quantum dots. According to optical studies, the ultraviolet emission is found to originate from the recombination of electron-hole pairs localized in the C=C bonds, while the blue emission is from the electron transition of sp{sup 2} domains.

  5. Resonant scattering of surface plasmon polaritons by dressed quantum dots

    SciTech Connect

    Huang, Danhong; Cardimona, Dave; Easter, Michelle; Gumbs, Godfrey; Maradudin, A. A.; Lin, Shawn-Yu; Zhang, Xiang

    2014-06-23

    The resonant scattering of surface plasmon-polariton waves (SPP) by embedded semiconductor quantum dots above the dielectric/metal interface is explored in the strong-coupling regime. In contrast to non-resonant scattering by a localized dielectric surface defect, a strong resonant peak in the spectrum of the scattered field is predicted that is accompanied by two side valleys. The peak height depends nonlinearly on the amplitude of SPP waves, reflecting the feedback dynamics from a photon-dressed electron-hole plasma inside the quantum dots. This unique behavior in the scattered field peak strength is correlated with the occurrence of a resonant dip in the absorption spectrum of SPP waves due to the interband photon-dressing effect. Our result on the scattering of SPP waves may be experimentally observable and applied to spatially selective illumination and imaging of individual molecules.

  6. Optical, electronic, and structural properties of uncoupled and close-packed arrays of InP quantum dots

    SciTech Connect

    Micic, O.I.; Jones, K.M.; Cahill, A.; Nozik, A.J.

    1998-12-03

    Solid films consisting of close-packed arrays of InP quantum dots have been prepared by slowly evaporating colloidal solutions of InP quantum dots. The diameters of the quantum dots were controlled to be between about 30 to 60 {angstrom}; size-selective precipitation yielded a size distribution of about 10% about the mean diameter. The arrays show regions of hexagonal order, as well as disordered regions. Oxide layers can form irreversibly on the quantum dot surface and limit the effectiveness of the size-selective precipitation. Photoluminescence spectra obtained from close-packed films of InP quantum dots formed from quantum dots with a single mean diameter and from a mixture of two quantum dot sizes show that energy transfer occurs from the photoexcited smaller quantum dots to the larger quantum dots. The efficiency of this energy transfer process is high.

  7. QCAD simulation and optimization of semiconductor double quantum dots

    SciTech Connect

    Nielsen, Erik; Gao, Xujiao; Kalashnikova, Irina; Muller, Richard Partain; Salinger, Andrew Gerhard; Young, Ralph Watson

    2013-12-01

    We present the Quantum Computer Aided Design (QCAD) simulator that targets modeling quantum devices, particularly silicon double quantum dots (DQDs) developed for quantum qubits. The simulator has three di erentiating features: (i) its core contains nonlinear Poisson, e ective mass Schrodinger, and Con guration Interaction solvers that have massively parallel capability for high simulation throughput, and can be run individually or combined self-consistently for 1D/2D/3D quantum devices; (ii) the core solvers show superior convergence even at near-zero-Kelvin temperatures, which is critical for modeling quantum computing devices; (iii) it couples with an optimization engine Dakota that enables optimization of gate voltages in DQDs for multiple desired targets. The Poisson solver includes Maxwell- Boltzmann and Fermi-Dirac statistics, supports Dirichlet, Neumann, interface charge, and Robin boundary conditions, and includes the e ect of dopant incomplete ionization. The solver has shown robust nonlinear convergence even in the milli-Kelvin temperature range, and has been extensively used to quickly obtain the semiclassical electrostatic potential in DQD devices. The self-consistent Schrodinger-Poisson solver has achieved robust and monotonic convergence behavior for 1D/2D/3D quantum devices at very low temperatures by using a predictor-correct iteration scheme. The QCAD simulator enables the calculation of dot-to-gate capacitances, and comparison with experiment and between solvers. It is observed that computed capacitances are in the right ballpark when compared to experiment, and quantum con nement increases capacitance when the number of electrons is xed in a quantum dot. In addition, the coupling of QCAD with Dakota allows to rapidly identify which device layouts are more likely leading to few-electron quantum dots. Very efficient QCAD simulations on a large number of fabricated and proposed Si DQDs have made it possible to provide fast feedback for design

  8. Exploring Competing Kinetic Processes in Quantum Dots Linked to Electrode

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Surfaces | MIT-Harvard Center for Excitonics Competing Kinetic Processes in Quantum Dots Linked to Electrode Surfaces March 14, 2012 at 2:30pm/4-349 Mark Hybertsen Brookhaven National Laboratory, Columbia University Mark_Hybertsen001_000 Abstract: Exploiting the unique properties of nanostructured chromophores for light harvesting applications relies on the balance between competing kinetic processes including energy transfer, carrier relaxation and carrier tunneling. In the first part of

  9. Fossil and synthetic fuels: miscellaneous. Part 1. Hearings before the Subcommittee on Fossil and Synthetic Fuels of the Committee on Energy and Commerce, House of Representatives, Ninety-Seventh Congress, First Session on Extension of IEA antitrust defense authorities, February 26, 1981, H. R. 2166, Department of Transportation authorization request, April 8, 1981, Gasohol usage in federal vehicles, July 30, 1981

    SciTech Connect

    Not Available

    1981-01-01

    Part I of the hearing record covers testimony relating to the extension of antitrust defense availability to the International Energy Agency (IEA); an authorization request by the Department of Transportation (DOT) to comply with pipeline safety regulations; and the administration's reluctance to promote gasohol use in federal vehicles. The first day's hearing included discussion of H.R. 2166, which extended the IEA authority by amending the Energy Policy and Conservation Act, and the testimony of four witnesses representing federal agencies involved in international affairs. On the second day, three DOT witnesses described pipeline-safety programs, enforcement, and procedures, with emphasis on the transport of liquefied natural gas. On the third day, nine witnesses representing gasohol-producing states, the US Army Equipment Research and Development Command, federal fleet services, and DOE examined the appropriateness and compliance record of Executive Order 12261 mandating gasohol for federally owned or leased vehicles. At issue was the need to convert Midwest grains to fuel at a time when oil is plentiful, the performance of alcohol fuels, and the administration's preference for working through the marketplace. Additional material submitted for the record follows each day's testimony. (DCK)

  10. Excited-state spectroscopy of InP quantum dots

    SciTech Connect

    Bertram, D.; Micic, O.I.; Nozik, A.J.

    1998-02-01

    We have measured low-temperature size-selective photoluminescence excitation spectra of high-quality InP quantum dots prepared by collodial chemistry. A set of samples with mean emission energies in the range from 1.9 to 2.2 eV was investigated. All samples have a size distribution of about 10{percent}, resulting in an inhomogeneously broadened photoluminescence lineshape. Due to the finite size distribution, spectra were collected at different detection wavelengths to reveal the energies of the excited excitonic states. The size dependence of the quantization energies of InP nanoparticles was determined by measuring photoluminescence excitation at different detection energies within one sample. Up to eight excited-state transitions in a set of seven samples were observed, as the estimated quantum dot size was scanned from 1.8 to 4.0 nm. A comparison of the observed peaks with a six-band {bold k}{center_dot}{bold p} calculation is given. In contrast to the successful interpretation in the case of CdSe, no agreement between the calculated and the observed excited-state energies is achieved. {copyright} {ital 1998} {ital The American Physical Society}

  11. Task 3: PNNL Visit by JAEA Researchers to Participate in TODAM Code Applications to Fukushima Rivers and to Evaluate the Feasibility of Adaptation of FLESCOT Code to Simulate Radionuclide Transport in the Pacific Ocean Coastal Water Around Fukushima

    SciTech Connect

    Onishi, Yasuo

    2013-03-29

    Four JAEA researchers visited PNNL for two weeks in February, 2013 to learn the PNNL-developed, unsteady, one-dimensional, river model, TODAM and the PNNL-developed, time-dependent, three dimensional, coastal water model, FLESCOT. These codes predict sediment and contaminant concentrations by accounting sediment-radionuclide interactions, e.g., adsorption/desorption and transport-deposition-resuspension of sediment-sorbed radionuclides. The objective of the river and coastal water modeling is to simulate • 134Cs and 137Cs migration in Fukushima rivers and the coastal water, and • their accumulation in the river and ocean bed along the Fukushima coast. Forecasting the future cesium behavior in the river and coastal water under various scenarios would enable JAEA to assess the effectiveness of various on-land remediation activities and if required, possible river and coastal water clean-up operations to reduce the contamination of the river and coastal water, agricultural products, fish and other aquatic biota. PNNL presented the following during the JAEA visit to PNNL: • TODAM and FLESCOT’s theories and mathematical formulations • TODAM and FLESCOT model structures • Past TODAM and FLESCOT applications • Demonstrating these two codes' capabilities by applying them to simple hypothetical river and coastal water cases. • Initial application of TODAM to the Ukedo River in Fukushima and JAEA researchers' participation in its modeling. PNNL also presented the relevant topics relevant to Fukushima environmental assessment and remediation, including • PNNL molecular modeling and EMSL computer facilities • Cesium adsorption/desorption characteristics • Experiences of connecting molecular science research results to macro model applications to the environment • EMSL tour • Hanford Site road tour. PNNL and JAEA also developed future course of actions for joint research projects on the Fukushima environmental and remediation assessments.

  12. Density functional calculation of the structural and electronic properties of germanium quantum dots

    SciTech Connect

    Anas, M. M.; Gopir, G.

    2015-04-24

    We apply first principles density functional computational methods to study the structures, densities of states (DOS), and higher occupied molecular orbital (HOMO) – lowest unoccupied molecular orbital (LUMO) gaps of selected free-standing Ge semiconductor quantum dots up to 1.8nm. Our calculations are performed using numerical atomic orbital approach where linear combination of atomic orbital was applied. The surfaces of the quantum dots was passivized by hydrogen atoms. We find that surface passivation does affect the electronic properties associated with the changes of surface state, electron localization, and the energy gaps of germanium nanocrystals as well as the confinement of electrons inside the quantum dots (QDs). Our study shows that the energy gaps of germanium quantum dots decreases with the increasing dot diameter. The size-dependent variations of the computed HOMO-LUMO gaps in our quantum dots model were found to be consistent with the effects of quantum confinement reported in others theoretical and experimental calculation.

  13. Fabrication and evaluation of series-triple quantum dots by thermal oxidation of silicon nanowire

    SciTech Connect

    Uchida, Takafumi Jo, Mingyu; Tsurumaki-Fukuchi, Atsushi; Arita, Masashi; Takahashi, Yasuo; Fujiwara, Akira

    2015-11-15

    Series-connected triple quantum dots were fabricated by a simple two-step oxidation technique using the pattern-dependent oxidation of a silicon nanowire and an additional oxidation of the nanowire through the gap of the fine gates attached to the nanowire. The characteristics of multi-dot single-electron devices are obtained. The formation of each quantum dot beneath an attached gate is confirmed by analyzing the electrical characteristics and by evaluating the gate capacitances between all pairings of gates and quantum dots. Because the gate electrode is automatically attached to each dot, the device structure benefits from scalability. This technique promises integrability of multiple quantum dots with individual control gates.

  14. Antimony mediated growth of high-density InAs quantum dots for photovoltaic cells

    SciTech Connect

    Tutu, F. K.; Wu, J.; Lam, P.; Tang, M.; Liu, H.; Miyashita, N.; Okada, Y.; Wilson, J.; Allison, R.

    2013-07-22

    We report enhanced solar cell performance using high-density InAs quantum dots. The high-density quantum dot was grown by antimony mediated molecular beam epitaxy. In-plane quantum dot density over 1 × 10{sup 11} cm{sup −2} was achieved by applying a few monolayers of antimony on the GaAs surface prior to quantum dot growth. The formation of defective large clusters was reduced by optimization of the growth temperature and InAs coverage. Comparing with a standard quantum dot solar cell without the incorporation of antimony, the high-density quantum dot solar cell demonstrates a distinct improvement in short-circuit current from 7.4 mA/cm{sup 2} to 8.3 mA/cm{sup 2}.

  15. Spectral and dynamical properties of single excitons, biexcitons, and trions in cesium-lead-halide perovskite quantum dots

    DOE PAGES [OSTI]

    Makarov, Nikolay Sergeevich; Guo, Shaojun; Isaienko, Oleksandr; Liu, Wenyong; Robel, Istvan; Klimov, Victor Ivanovich

    2016-02-16

    Organic–inorganic lead-halide perovskites have been the subject of recent intense interest due to their unusually strong photovoltaic performance. A new addition to the perovskite family is all-inorganic Cs–Pb-halide perovskite nanocrystals, or quantum dots, fabricated via a moderate-temperature colloidal synthesis. While being only recently introduced to the research community, these nanomaterials have already shown promise for a range of applications from color-converting phosphors and light-emitting diodes to lasers, and even room-temperature single-photon sources. Knowledge of the optical properties of perovskite quantum dots still remains vastly incomplete. Here we apply various time-resolved spectroscopic techniques to conduct a comprehensive study of spectral andmore » dynamical characteristics of single- and multiexciton states in CsPbX3 nanocrystals with X being either Br, I, or their mixture. Specifically, we measure exciton radiative lifetimes, absorption cross-sections, and derive the degeneracies of the band-edge electron and hole states. We also characterize the rates of intraband cooling and nonradiative Auger recombination and evaluate the strength of exciton–exciton coupling. The overall conclusion of this work is that spectroscopic properties of Cs–Pb-halide quantum dots are largely similar to those of quantum dots of more traditional semiconductors such as CdSe and PbSe. At the same time, we observe some distinctions including, for example, an appreciable effect of the halide identity on radiative lifetimes, considerably shorter biexciton Auger lifetimes, and apparent deviation of their size dependence from the “universal volume scaling” previously observed for many traditional nanocrystal systems. The high efficiency of Auger decay in perovskite quantum dots is detrimental to their prospective applications in light-emitting devices and lasers. Furthermore, this points toward the need for the development of approaches for effective

  16. Research and development of Proton-Exchange-Membrane (PEM) fuel cell system for transportation applications. Fuel cell infrastructure and commercialization study

    SciTech Connect

    1996-11-01

    This paper has been prepared in partial fulfillment of a subcontract from the Allison Division of General Motors under the terms of Allison`s contract with the U.S. Department of Energy (DE-AC02-90CH10435). The objective of this task (The Fuel Cell Infrastructure and Commercialization Study) is to describe and prepare preliminary evaluations of the processes which will be required to develop fuel cell engines for commercial and private vehicles. This report summarizes the work undertaken on this study. It addresses the availability of the infrastructure (services, energy supplies) and the benefits of creating public/private alliances to accelerate their commercialization. The Allison prime contract includes other tasks related to the research and development of advanced solid polymer fuel cell engines and preparation of a demonstration automotive vehicle. The commercialization process starts when there is sufficient understanding of a fuel cell engine`s technology and markets to initiate preparation of a business plan. The business plan will identify each major step in the design of fuel cell (or electrochemical) engines, evaluation of the markets, acquisition of manufacturing facilities, and the technical and financial resources which will be required. The process will end when one or more companies have successfully developed and produced fuel cell engines at a profit. This study addressed the status of the information which will be required to prepare business plans, develop the economic and market acceptance data, and to identify the mobility, energy and environment benefits of electrochemical or fuel cell engines. It provides the reader with information on the status of fuel cell or electrochemical engine development and their relative advantages over competitive propulsion systems. Recommendations and descriptions of additional technical and business evaluations that are to be developed in more detail in Phase II, are included.

  17. The emission wavelength dependent photoluminescence lifetime of the N-doped graphene quantum dots

    SciTech Connect

    Deng, Xingxia; Sun, Jing; Yang, Siwei; Ding, Guqiao; Shen, Hao; Zhou, Wei; Lu, Jian; Wang, Zhongyang

    2015-12-14

    Aromatic nitrogen doped graphene quantum dots were investigated by steady-state and time-resolved photoluminescence (PL) techniques. The PL lifetime was found to be dependent on the emission wavelength and coincident with the PL spectrum, which is different from most semiconductor quantum dots and fluorescent dyes. This result shows the synergy and competition between the quantum confinement effect and edge functional groups, which may have the potential to guide the synthesis and expand the applications of graphene quantum dots.

  18. Formation of long-range ordered quantum dots arrays in amorphous matrix by ion beam irradiation

    SciTech Connect

    Buljan, M.; Bogdanovic-Radovic, I.; Karlusic, M.; Desnica, U. V.; Radic, N.; Dubcek, P.; Drazic, G.; Salamon, K.; Bernstorff, S.; Holy, V.

    2009-08-10

    We demonstrate the production of a well ordered three-dimensional array of Ge quantum dots in amorphous silica matrix. The ordering is achieved by ion beam irradiation and annealing of a multilayer film. Structural analysis shows that quantum dots nucleate along the direction of the ion beam used for irradiation, while the mutual distance of the quantum dots is determined by the diffusion properties of the multilayer material rather than the distances between traces of ions that are used for irradiation.

  19. Coupling single giant nanocrystal quantum dots to the fundamental mode of

    Office of Scientific and Technical Information (OSTI)

    patch nanoantennas through fringe field (Journal Article) | SciTech Connect Coupling single giant nanocrystal quantum dots to the fundamental mode of patch nanoantennas through fringe field Citation Details In-Document Search Title: Coupling single giant nanocrystal quantum dots to the fundamental mode of patch nanoantennas through fringe field Through single dot spectroscopy and numerical simulation studies, we demonstrate that the fundamental mode of gold patch nanoantennas have

  20. Supertruck - Improving Transportation Efficiency through Integrated

    Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)

    Vehicle, Engine and Powertrain Research | Department of Energy Supertruck - Improving Transportation Efficiency through Integrated Vehicle, Engine and Powertrain Research Supertruck - Improving Transportation Efficiency through Integrated Vehicle, Engine and Powertrain Research 2012 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Program Annual Merit Review and Peer Evaluation Meeting ace058_sisken_2012_o.pdf (1.87 MB) More Documents & Publications SuperTruck Program: Engine

  1. Feasibility study for a transportation operations system cask maintenance facility

    SciTech Connect

    Rennich, M.J.; Medley, L.G.; Attaway, C.R.

    1991-01-01

    The US Department of Energy (DOE), Office of Civilian Radioactive Waste Management (OCRWM) is responsible for the development of a waste management program for the disposition of spent nuclear fuel (SNF) and high-level waste (HLW). The program will include a transportation system for moving the nuclear waste from the sources to a geologic repository for permanent disposal. Specially designed casks will be used to safely transport the waste. The cask systems must be operated within limits imposed by DOE, the Nuclear Regulatory Commission (NRC), and the Department of Transportation (DOT). A dedicated facility for inspecting, testing, and maintaining the cask systems was recommended by the General Accounting Office (in 1979) as the best means of assuring their operational effectiveness and safety, as well as regulatory compliance. In November of 1987, OCRWM requested a feasibility study be made of a Cask Maintenance Facility (CMF) that would perform the required functions. 46 refs., 16 figs., 13 tabs.

  2. Current density fluctuations and ambipolarity of transport

    SciTech Connect

    Shen, W.; Dexter, R.N.; Prager, S.C.

    1991-10-01

    The fluctuation in the plasma current density is measured in the MIST reversed field pinch experiment. Such fluctuations, and the measured radial profile of the k spectrum of magnetic fluctuations, supports the view and that low frequency fluctuations (f < 30 kHz) are tearing modes and high frequency fluctuations (30 kHz < f < 250 kHz) are localized turbulence in resonance with the local equilibrium magnetic field (i.e., k {center_dot} B = 0). Correlation of current density and magnetic fluctuations (< {tilde j}{parallel}{tilde B}{sub r} >) demonstrates that radial particle transport from particle motion parallel to a fluctuating magnetic field is ambipolar over the full frequency range.

  3. Current density fluctuations and ambipolarity of transport

    SciTech Connect

    Shen, W.; Dexter, R.N.; Prager, S.C.

    1991-10-01

    The fluctuation in the plasma current density is measured in the MIST reversed field pinch experiment. Such fluctuations, and the measured radial profile of the k spectrum of magnetic fluctuations, supports the view and that low frequency fluctuations (f < 30 kHz) are tearing modes and high frequency fluctuations (30 kHz < f < 250 kHz) are localized turbulence in resonance with the local equilibrium magnetic field (i.e., k {center dot} B = 0). Correlation of current density and magnetic fluctuations (< {tilde j}{parallel}{tilde B}{sub r} >) demonstrates that radial particle transport from particle motion parallel to a fluctuating magnetic field is ambipolar over the full frequency range.

  4. Excited-State Relaxation in PbSe Quantum Dots

    SciTech Connect

    An, J. M.; Califano, M.; Franceschetti, A.; Zunger, A.

    2008-01-01

    In solids the phonon-assisted, nonradiative decay from high-energy electronic excited states to low-energy electronic excited states is picosecond fast. It was hoped that electron and hole relaxation could be slowed down in quantum dots, due to the unavailability of phonons energy matched to the large energy-level spacings ('phonon-bottleneck'). However, excited-state relaxation was observed to be rather fast ({le}1 ps) in InP, CdSe, and ZnO dots, and explained by an efficient Auger mechanism, whereby the excess energy of electrons is nonradiatively transferred to holes, which can then rapidly decay by phonon emission, by virtue of the densely spaced valence-band levels. The recent emergence of PbSe as a novel quantum-dot material has rekindled the hope for a slow down of excited-state relaxation because hole relaxation was deemed to be ineffective on account of the widely spaced hole levels. The assumption of sparse hole energy levels in PbSe was based on an effective-mass argument based on the light effective mass of the hole. Surprisingly, fast intraband relaxation times of 1-7 ps were observed in PbSe quantum dots and have been considered contradictory with the Auger cooling mechanism because of the assumed sparsity of the hole energy levels. Our pseudopotential calculations, however, do not support the scenario of sparse hole levels in PbSe: Because of the existence of three valence-band maxima in the bulk PbSe band structure, hole energy levels are densely spaced, in contradiction with simple effective-mass models. The remaining question is whether the Auger decay channel is sufficiently fast to account for the fast intraband relaxation. Using the atomistic pseudopotential wave functions of Pb{sub 2046}Se{sub 2117} and Pb{sub 260}Se{sub 249} quantum dots, we explicitly calculated the electron-hole Coulomb integrals and the P {yields} S electron Auger relaxation rate. We find that the Auger mechanism can explain the experimentally observed P {yields} S

  5. Charging dynamics of a floating gate transistor with site-controlled quantum dots

    SciTech Connect

    Maier, P. Hartmann, F.; Emmerling, M.; Schneider, C.; Höfling, S.; Kamp, M.; Worschech, L.

    2014-08-04

    A quantum dot memory based on a GaAs/AlGaAs quantum wire with site-controlled InAs quantum dots was realized by means of molecular beam epitaxy and etching techniques. By sampling of different gate voltage sweeps for the determination of charging and discharging thresholds, it was found that discharging takes place at short time scales of μs, whereas several seconds of waiting times within a distinct negative gate voltage range were needed to charge the quantum dots. Such quantum dot structures have thus the potential to implement logic functions comprising charge and time dependent ingredients such as counting of signals or learning rules.

  6. Red shift in the photoluminescence of colloidal carbon quantum dots induced by photon reabsorption

    SciTech Connect

    Zhang, Wenxia; Dai, Dejian; Chen, Xifang; Guo, Xiaoxiao; Fan, Jiyang

    2014-03-03

    We synthesize the colloidal carbon/graphene quantum dots 1–9 nm in diameter and study their photoluminescence properties. Surprisingly, the luminescence properties of a fixed collection of colloidal carbon quantum dots can be systematically changed as the concentration varies. A model based on photon reabsorption is proposed which explains well the experiment. Infrared spectral study indicates that the surfaces of the carbon quantum dots are substantially terminated by oxygen atoms, which causes their ultra-high hydrophilicity. Our result clarifies the mystery of distinct emission colors in carbon quantum dots and indicates that photon reabsorption can strongly affect the luminescence properties of colloidal nanocrystals.

  7. Improvement of plasmonic enhancement of quantum dot emission via an intermediate silicon-aluminum oxide interface

    SciTech Connect

    Wing, Waylin J.; Sadeghi, Seyed M. Campbell, Quinn

    2015-01-05

    We studied the emission of quantum dots in the presence of plasmon-metal oxide substrates, which consist of arrays of metallic nanorods embedded in amorphous silicon coated with a nanometer-thin layer of aluminum oxide on the top. We showed that the combined effects of plasmons and the silicon-aluminum oxide interface can lead to significant enhancement of the quantum efficiency of quantum dots. Our results show that such an interface can significantly enhance plasmonic effects of the nanorods via quantum dot-induced exciton-plasmon coupling, leading to partial polarization of the quantum dots' emission.

  8. R&D Magazine: Windows into Solar Power Sources with Quantum Dots

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    R&D Magazine: Windows into Solar Power Sources with Quantum Dots A luminescent solar concentrator is an emerging sunlight harvesting technology that has the potential to disrupt ...

  9. Giant Nanocrystal Quantum Dots as Stable and Efficient Down-Conversion...

    Office of Scientific and Technical Information (OSTI)

    State Lighting Citation Details In-Document Search Title: Giant Nanocrystal Quantum Dots as Stable and Efficient Down-Conversion Phosphor for LED based Solid State Lighting You ...

  10. In the OSTI Collections: Quantum Dots | OSTI, US Dept of Energy...

    Office of Scientific and Technical Information (OSTI)

    ... Strongly Coupled Quantum Dot Solids"SciTech Connect, in which electrical noise, and the effects on electrical conductivity of magnetic fields and chemical modifications, were ...

  11. Giant Nanocrystal Quantum Dots as Stable and Efficient Down-Conversion

    Office of Scientific and Technical Information (OSTI)

    Dots as Stable and Efficient Down-Conversion Phosphor for LED based Solid State Lighting Kundu, Janardan Los Alamos National Laboratory; Ghosh, Yagnaseni Los Alamos...

  12. UltraDots Inc formely UltraPhotonics | Open Energy Information

    OpenEI (Open Energy Information) [EERE & EIA]

    ) Place: Fremont, California Zip: CA 94539 Product: Nanotechnology company developing "quantum dot" technology for a range of energy, communications and medical applications....

  13. Quantum Dots Promise to Significantly Boost Photovoltaic Efficiencies; The Spectrum of Clean Energy Innovation (Fact Sheet)

    SciTech Connect

    Not Available

    2010-06-01

    Fact sheet describing NREL's discovery that quantum dots--semiconductor nanocrystals--can dramatically increase the efficiency of converting sunlight to electricity.

  14. Observation of the Kondo effect in a spin-3/2 hole quantum dot (Journal

    Office of Scientific and Technical Information (OSTI)

    Article) | SciTech Connect Observation of the Kondo effect in a spin-3/2 hole quantum dot Citation Details In-Document Search Title: Observation of the Kondo effect in a spin-3/2 hole quantum dot We report the observation of the Kondo effect in a spin-3/2 hole quantum dot formed near pinch-off in a GaAs quantum wire. We clearly observe two distinctive hallmarks of quantum dot Kondo physics. First, the zero-bias peak in the differential conductance splits an in-plane magnetic field and the

  15. Development of Onsite Transportation Safety Documents for Nevada Test Site

    SciTech Connect

    Frank Hand, Willard Thomas, Frank Sciacca, Manny Negrete, Susan Kelley

    2008-05-08

    Department of Energy (DOE) Orders require each DOE site to develop onsite transportation safety documents (OTSDs). The Nevada Test Site approach divided all onsite transfers into two groups with each group covered by a standalone OTSD identified as Non-Nuclear and Nuclear. The Non-Nuclear transfers involve all radioactive hazardous material in less than Hazard Category (HC)-3 quantities and all chemically hazardous materials. The Nuclear transfers involve all radioactive material equal to or greater than HC-3 quantities and radioactive material mated with high explosives regardless of quantity. Both OTSDs comply with DOE O 460.1B requirements. The Nuclear OTSD also complies with DOE O 461.1A requirements and includes a DOE-STD-3009 approach to hazard analysis (HA) and accident analysis as needed. All Nuclear OTSD proposed transfers were determined to be non-equivalent and a methodology was developed to determine if “equivalent safety” to a fully compliant Department of Transportation (DOT) transfer was achieved. For each HA scenario, three hypothetical transfers were evaluated: a DOT-compliant, uncontrolled, and controlled transfer. Equivalent safety is demonstrated when the risk level for each controlled transfer is equal to or less than the corresponding DOT-compliant transfer risk level. In this comparison the typical DOE-STD-3009 risk matrix was modified to reflect transportation requirements. Design basis conditions (DBCs) were developed for each non-equivalent transfer. Initial DBCs were based solely upon the amount of material present. Route-, transfer-, and site-specific conditions were evaluated and the initial DBCs revised as needed. Final DBCs were evaluated for each transfer’s packaging and its contents.

  16. Transporting particulate material

    DOEpatents

    Aldred, Derek Leslie; Rader, Jeffrey A.; Saunders, Timothy W.

    2011-08-30

    A material transporting system comprises a material transporting apparatus (100) including a material transporting apparatus hopper structure (200, 202), which comprises at least one rotary transporting apparatus; a stationary hub structure (900) constraining and assisting the at least one rotary transporting apparatus; an outlet duct configuration (700) configured to permit material to exit therefrom and comprising at least one diverging portion (702, 702'); an outlet abutment configuration (800) configured to direct material to the outlet duct configuration; an outlet valve assembly from the material transporting system venting the material transporting system; and a moving wall configuration in the material transporting apparatus capable of assisting the material transporting apparatus in transporting material in the material transporting system. Material can be moved from the material transporting apparatus hopper structure to the outlet duct configuration through the at least one rotary transporting apparatus, the outlet abutment configuration, and the outlet valve assembly.

  17. International Conference on Surface Transportation System Resilience to Climate Change and Extreme Weather Events

    Energy.gov [DOE]

    The conference will provide transportation professionals with information on emerging best practices and state of the art research results on how to adapt surface transportation networks to the...

  18. Transportation Beamline at the Advanced Photon Source | Argonne National

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Laboratory Transportation Beamline at the Advanced Photon Source Argonne's dedicated transportation research beamline at Argonne's Advanced Photon Source (APS) allows researchers to use the powerful X-ray beams created by the APS to penetrate materials and reveal details that cannot otherwise be seen. Transportation researchers use this tool to peer inside liquid sprays from fuel injectors for diesel engines. With a greater understanding of fuel spray composition, researchers have the

  19. Electrofuels: Versatile Transportation Energy Solutions

    SciTech Connect

    2010-07-01

    Electrofuels Project: ARPA-E’s Electrofuels Project is using microorganisms to create liquid transportation fuels in a new and different way that could be up to 10 times more energy efficient than current biofuel production methods. ARPA-E is the only U.S. government agency currently funding research on Electrofuels.

  20. Transportation Data Programs:Transportation Energy Data Book...

    Office of Energy Efficiency and Renewable Energy (EERE) (indexed site)

    Transportation Data Programs:Transportation Energy Data Book,Vehicle Technologies Market Report, and VT Fact of the Week Transportation Data Programs:Transportation Energy Data ...

  1. Grazing-incidence small-angle X-ray scattering: application to the study of quantum dot lattices

    SciTech Connect

    Buljan, Maja Radi?, Nikola; Bernstorff, Sigrid; Drai?, Goran; Bogdanovi?-Radovi?, Iva; Hol, Vclav

    2012-01-01

    The modelling of grazing-incidence small-angle X-ray scattering (GISAXS) from three-dimensional quantum dot lattices is described. The ordering of quantum dots in three-dimensional quantum dot lattices is investigated by grazing-incidence small-angle X-ray scattering (GISAXS). Theoretical models describing GISAXS intensity distributions for three general classes of lattices of quantum dots are proposed. The classes differ in the type of disorder of the positions of the quantum dots. The models enable full structure determination, including lattice type, lattice parameters, the type and degree of disorder in the quantum dot positions and the distributions of the quantum dot sizes. Applications of the developed models are demonstrated using experimentally measured data from several types of quantum dot lattices formed by a self-assembly process.

  2. Layered insulator hexagonal boron nitride for surface passivation in quantum dot solar cell

    SciTech Connect

    Shanmugam, Mariyappan; Jain, Nikhil; Jacobs-Gedrim, Robin; Yu, Bin; Xu, Yang

    2013-12-09

    Single crystalline, two dimensional (2D) layered insulator hexagonal boron nitride (h-BN), is demonstrated as an emerging material candidate for surface passivation on mesoporous TiO{sub 2}. Cadmium selenide (CdSe) quantum dot based bulk heterojunction (BHJ) solar cell employed h-BN passivated TiO{sub 2} as an electron acceptor exhibits photoconversion efficiency ?46% more than BHJ employed unpassivated TiO{sub 2}. Dominant interfacial recombination pathways such as electron capture by TiO{sub 2} surface states and recombination with hole at valence band of CdSe are efficiently controlled by h-BN enabled surface passivation, leading to improved photovoltaic performance. Highly crystalline, confirmed by transmission electron microscopy, dangling bond-free 2D layered h-BN with self-terminated atomic planes, achieved by chemical exfoliation, enables efficient passivation on TiO{sub 2}, allowing electronic transport at TiO{sub 2}/h-BN/CdSe interface with much lower recombination rate compared to an unpassivated TiO{sub 2}/CdSe interface.

  3. Quality Assurance Program Plan for the Hazardous Materials Transportation and Packaging Program. Revision 1

    SciTech Connect

    Calihan, T.W. III; Votaw, E.F.

    1995-05-01

    This QAPP covers only the implementation accomplished through Level I and II manuals. It covers the quality affecting activities identified in USDOE orders (both HQ and Richland Operations Office), US DOT, US EPA, and NRC regulations, IAEA guidelines, and the WHC manuals. It covers activities related to hazardous materials transportation performed on and off the Hanford site under the jurisdictional authority of WHC. (Hazardous materials include radioactive, hazardous waste, and mixed waste.)

  4. Single-charge transport in ambipolar silicon nanoscale field-effect transistors

    SciTech Connect

    Mueller, Filipp; Konstantaras, Georgios; Wiel, Wilfred G. van der; Zwanenburg, Floris A.

    2015-04-27

    We report single-charge transport in ambipolar nanoscale MOSFETs, electrostatically defined in near-intrinsic silicon. We use the ambipolarity to demonstrate the confinement of either a few electrons or a few holes in exactly the same crystalline environment underneath a gate electrode. We find similar electron and hole quantum dot properties while the mobilities differ quantitatively like in microscale devices. The understanding and control of individual electrons and holes are essential for spin-based quantum information processing.

  5. Packaging and Transportation for Offsite Shipment of Materials of National Security Interest

    Directives, Delegations, and Other Requirements [Office of Management (MA)]

    2010-12-20

    The purpose of this Order is to make clear that the packaging and transportation of all offsite shipments of materials of national security interest for DOE must be conducted in accordance with DOT and Nuclear Regulatory Commission (NRC) regulations that would be applicable to comparable commercial shipments, except where an alternative course of action is identified in this Order. Supersedes DOE O 461.1A.

  6. The Complex Systems Landscape of Future Urban Transportation | Argonne

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    National Laboratory The Complex Systems Landscape of Future Urban Transportation In an effort "to examine the nexus of energy and mobility for future transportation systems," the U.S. Department of Energy (DOE) has launched the Systems and Modeling for Accelerated Research in Transportation (SMART) Mobility consortium. By studying mobility as a system researchers can predict future trends, an invaluable asset to policymakers as they prepare for the future of transportation. This

  7. National Transportation Stakeholders Forum

    Office of Environmental Management (EM)

    National Transportation Stakeholders Forum OSRP * NNSA Contractors transporting in commerce, are required law to comply with applicable regulations required law to comply with ...

  8. Transportation sector energy consumption

    Annual Energy Outlook

    Chapter 8 Transportation sector energy consumption Overview In the International Energy Outlook 2016 (IEO2016) Reference case, transportation sector delivered energy consumption ...

  9. Negative circular polarization as a universal property of quantum dots

    SciTech Connect

    Taylor, Matthew W.; Spencer, Peter; Murray, Ray

    2015-03-23

    This paper shows that negative circular polarization, a spin flip of polarized carriers resulting in emission of opposite helicity, can be observed in undoped, n-doped, and p-doped InAs/GaAs quantum dots. These results contradict the usual interpretation of the effect. We show using power dependent and time resolved spectroscopy that the generation of negative circular polarization correlates with excited state emission. Furthermore, a longer spin lifetime of negatively polarized excitons is observed where emission is largely ground state in character.

  10. A nonlinear Bloch model for Coulomb interaction in quantum dots

    SciTech Connect

    Bidegaray-Fesquet, Brigitte Keita, Kole

    2014-02-15

    In this paper, we first derive a Coulomb Hamiltonian for electron–electron interaction in quantum dots in the Heisenberg picture. Then we use this Hamiltonian to enhance a Bloch model, which happens to be nonlinear in the density matrix. The coupling with Maxwell equations in case of interaction with an electromagnetic field is also considered from the Cauchy problem point of view. The study is completed by numerical results and a discussion about the advisability of neglecting intra-band coherences, as is done in part of the literature.

  11. Computational modeling of electrophotonics nanomaterials: Tunneling in double quantum dots

    SciTech Connect

    Vlahovic, Branislav Filikhin, Igor

    2014-10-06

    Single electron localization and tunneling in double quantum dots (DQD) and rings (DQR) and in particular the localized-delocalized states and their spectral distributions are considered in dependence on the geometry of the DQDs (DQRs). The effect of violation of symmetry of DQDs geometry on the tunneling is studied in details. The cases of regular and chaotic geometries are considered. It will be shown that a small violation of symmetry drastically affects localization of electron and that anti-crossing of the levels is the mechanism of tunneling between the localized and delocalized states in DQRs.

  12. Electronic structure of nanocrystal quantum-dot quantumwells

    SciTech Connect

    Schrier, Joshua; Wang, Lin-Wang

    2006-06-26

    The electronic states of CdS/CdSe/CdS colloidal nanocrystalquantum-dot quantum wells are studied by large-scale pseudopotentiallocal density approximation (LDA) calculations. Using this approach, wedetermine the effects of CdS core size, CdSe well thickness, and CdSshell thickness on the band-edge wave functions, band-gap, andelectron-hole Coulomb interactions. We find the conduction-band wavefunction to be less confined to the CdSe well layer than predicted by kcdot p effective-mass theory, which accounts for the previous underestimation of the electron g factor.

  13. Photoluminescence-enhanced biocompatible quantum dots by phospholipid functionalization

    SciTech Connect

    Shi Yunfeng; He Peng Zhu Xinyuan

    2008-10-02

    A simple two-step strategy using phospholipid (PPL) to functionalize core/shell CdSe/ZnS quantum dots (QDs) has been described. The experimental data show that the use of S-H terminated PPL results not only in the high colloidal stability of core/shell CdSe/ZnS QDs in the aqueous phase, but also in the significant enhancement of photoluminescence. The degree of the enhancement is a function of the PPL-CdSe/ZnS QDs sample concentration. These results might be promising for future biological platform in new devices ranging from photovoltaic cells to biosensors and other devices.

  14. Activation of molecular catalysts using semiconductor quantum dots

    DOEpatents

    Meyer, Thomas J.; Sykora, Milan; Klimov, Victor I.

    2011-10-04

    Photocatalytic materials based on coupling of semiconductor nanocrystalline quantum dots (NQD) and molecular catalysts. These materials have capability to drive or catalyze non-spontaneous chemical reactions in the presence of visible radiation, ultraviolet radiation, or both. The NQD functions in these materials as a light absorber and charge generator. Following light absorption, the NQD activates a molecular catalyst adsorbed on the surface of the NQD via transfer of one or more charges (either electrons or electron-holes) from the NQD to the molecular catalyst. The activated molecular catalyst can then drive a chemical reaction. A photoelectrolytic device that includes such photocatalytic materials is also described.

  15. Prediction of a strain-induced conduction-band minimum in embedded quantum dots

    SciTech Connect

    Williamson, A.J.; Zunger, A.; Canning, A.

    1998-02-01

    Free-standing InP quantum dots have previously been theoretically and experimentally shown to have a direct band gap across a large range of experimentally accessible sizes. We demonstrated that when these dots are embedded coherently within a GaP barrier material, the effects of quantum confinement in conjunction with coherent strain suggest there will be a critical diameter of dot ({approx}60 {Angstrom}), above which the dot is direct, type I, and below which it is indirect, type II. However, the strain in the system acts to produce another conduction state with an even lower energy, in which electrons are localized in small pockets at the interface between the InP dot and the GaP barrier. Since this conduction state is GaP X{sub 1c} derived and the highest occupied valence state is InP, {Gamma} derived, the fundamental transition is predicted to be indirect in both real and reciprocal space ({open_quotes}type II{close_quotes}) for all dot sizes. This effect is peculiar to the strained dot, and is absent in the freestanding dot. {copyright} {ital 1998} {ital The American Physical Society}

  16. Probing the size and environment induced phase transformation in CdSe quantum dots

    SciTech Connect

    Karakoti, Ajay S.; Sanghavi, Shail P.; Nachimuthu, Ponnusamy; Yang, Ping; Thevuthasan, Suntharampillai

    2011-11-17

    The structural and electronic properties of CdSe quantum dots in toluene and drop-casted on Si wafer were investigated by in-situ micro X-ray diffraction, X-ray photoelectron spectroscopy and UV-Vis absorption and emission spectroscopy. The in-situ micro diffraction data show that the CdSe quantum dots capped with TOPO or hexadecylamine (HDA) in toluene exhibit predominantly wurtzite crystal structure, which undergoes a phase transformation to zinc blende crystal structure following drop casting on Si and this phase transition increases with decreasing the size of the CdSe quantum dots. Decreasing the size of quantum dots also increases the Se vacancies that facilitate the phase transformation. The X-ray photoelectron spectra show a systematic increase in the core level binding energies of Cd 3d and Se 3d, the band gap and the Cd/Se ratio as the size of the quantum dots decreases from 6.6nm to 2.1nm. This is attributed to the quantum confinement of CdSe crystallites by the capping ligands in toluene which increases with decreasing the size of the quantum dots. However, drop-casting quantum dots on Si alter the density and arrangement of capping ligands and solvent molecules on the quantum dots which causes significant phase transformation.

  17. Statistical theory of Coulomb blockade oscillations: Quantum chaos in quantum dots

    SciTech Connect

    Jalabert, R.A.; Stone, A.D.; Alhassid, Y. (Center for Theoretical Physics, Sloane Physics Laboratory, Yale University, New Haven, Connecticut 06511 (United States))

    1992-06-08

    We develop a statistical theory of the amplitude of Coulomb blockade oscillations in semiconductor quantum dots based on the hypothesis that chaotic dynamics in the dot potential leads to behavior described by random-matrix theory. Breaking time-reversal symmetry is predicted to cause an experimentally observable change in the distribution of amplitudes. The theory is tested numerically and good agreement is found.

  18. NREL: Transportation Research - Fuel Combustion Laboratory

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Combustion Laboratory NREL's Fuel Combustion Laboratory focuses on characterizing fuels at the molecular level. This information can then be used to understand and predict a fuel's effect on engine performance and emissions. By understanding the effects of fuel chemistry on ignition, as well as the potential emissions impacts, we can develop fuels that enable more efficient engine designs, using both today's technology and future advanced combustion concepts. This lab supports the Renewable

  19. NREL: Transportation Research - Future Automotive Systems Technology

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Simulator Future Automotive Systems Technology Simulator FASTSim icon The FASTSim simulation tool evaluates the impact of technology improvements on efficiency, performance, cost, and battery life in conventional and advanced vehicles. Developed by NREL, the Future Automotive Systems Technology Simulator (FASTSim) evaluates the impact of technology improvements on efficiency, performance, cost, and battery life in conventional vehicles, hybrid electric vehicles (HEVs), plug-in hybrid

  20. NREL: Transportation Research - Truck Platooning Testing

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Truck Platooning Testing Photo of two tractor trailer trucks driving in close proximity. NREL conducted track testing of platooned tractors with 53-ft trailers at the 8.5-mile Uvalde track in San Antonio, Texas. Photo courtesy of Peloton NREL's fleet test and evaluation team assesses the fuel savings potential of semiautomated truck platooning of line-haul sleeper cabs with modern aerodynamics. Platooning reduces aerodynamic drag by grouping vehicles together and safely decreasing the distance

  1. NREL: Transportation Research - Alternative Fuel Fleet Vehicle...

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Although biodiesel is the most commonly used alternative fuel in medium- and heavy-duty ... fuel cell buses. Renewable Diesel and Biodiesel Renewable diesel is a conventional ...

  2. NREL: Transportation Research - News Release Archives

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    fuels, including electricity, natural gas, biodiesel, e85 Ethanol, propane and hydrogen. ... NREL Survey Shows Dramatic Improvement in B100 Biodiesel Quality The latest national ...

  3. NREL: Transportation Research - Vehicle Thermal Management Publication...

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    ... Fuel Use from Cabin Ventilation, Solar-Reflective Paint, and New Solar-Reflective Glazing. ... Kogler, R. Presented at the 2007 SAE World Congress April 16-19, 2007, Detroit, Michigan. ...

  4. NREL: Transportation Research - News Release Archives

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    5 December 16, 2015 Helping Electric-Drive Vehicle Power Electronics Keep Their Cool Conventional thermal interface materials can pose a significant bottleneck to heat removal from ...

  5. NREL: Transportation Research - Electric Vehicle Technologies...

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Electric Vehicle Technologies and Targets The U.S. Department of Energy and the cross-agency EV Everywhere Grand Challenge initiative have set goals for plug-in electric vehicles ...

  6. NREL: Transportation Research - News Release Archives

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    1 December 13, 2011 NREL Adds Electric Vehicle to its Advanced Vehicle Fleet NREL will use the new electric vehicle for studies related to charge management and performance, ...

  7. NREL: Transportation Research - Fleet Test and Evaluation

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Fleet Test and Evaluation Photo of medium-duty truck with the words plug-in all electric vehicle on its side. NREL evaluates the real-world performance of advanced medium- and ...

  8. NREL: Transportation Research - Hybrid Electric Fleet Vehicle...

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Hybrid Electric Fleet Vehicle Testing How Hybrid Electric Vehicles Work Hybrid electric vehicles combine a primary power source, an energy storage system, and an electric motor to ...

  9. NREL: Transportation Research - Electric Vehicle Grid Integration

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Electric Vehicle Grid Integration Illustration of a house with a roof-top photovoltaic system. A wind turbine and utility towers appear in the background. A car, parked in the ...

  10. TRANSFORUM News from Argonne's Transportation Research Program

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    adoption of these vehicles, particularly in more difficult markets, and a rapidly growing charging infrastructure is taking hold. But like the Chinese concept of yin and yang, with...

  11. NREL: Transportation Research - Systems Analysis and Integration...

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Sun Matt Thornton Lijuan Wang Eric Wood Stan Young Lei Zhu All of the above Keywords: Battery wear Connected and automated vehicles Drive cycles Electric vehicles Fuel cell ...

  12. NREL: Transportation Research - Power Electronics and Electric...

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    ... Paper Source: Bennion, Kevin; Moreno, Gilberto. (2015). Presented at the International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic ...

  13. NREL: Transportation Research - Systems Analysis and Integration

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    NREL's systems analysis and integration team evaluates the impact of emerging technologies on efficiency, performance, cost, and battery life for a full range of ...

  14. Polymer matrix composites research: A survey of federally sponsored programs

    SciTech Connect

    Not Available

    1990-06-01

    This report identifies research conducted by agencies of the federal government other than the Department of Energy (DOE) in the area of advanced polymer matrix composites (PMCs). DOE commissioned the report to avoid duplicating other agencies' efforts in planning its own research program for PMCs. PMC materials consist of high-strength, short or continuous fibers fused together by an organic matrix. Compared to traditional structural metals, PMCs provide greater strength and stiffness, reduced weight and increased heat resistance. The key contributors to PMC research identified by the survey are the Department of Defense (DOD), the National Aeronautics and Space Administration (NASA), the National Science Foundation (NSF), and the Department of Transportation (DOT). The survey identified a total of 778 projects. More than half of the total projects identified emphasize materials research with a goal toward developing materials with improved performance. Although an almost equal number of identified materials projects focus on thermosets and thermoplastics receive more attention because of their increased impact resistance and their easy formability and re-formability. Slightly more than one third of projects identified target structures research. Only 15 percent of the projects identified focus on manufacturing techniques, despite the need for efficient, economical methods manufacturing products constructed of PMCs--techniques required for PMCs to gain widespread acceptance. Three issues to be addressed concerning PMCs research are economy of use, improvements in processing, and education and training. Five target technologies have been identified that could benefit greatly from increased use of PMCs: aircraft fuselages, automobile frames, high-speed machinery, electronic packaging, and construction.

  15. Water-soluble luminescent quantum dots and biomolecular conjugates thereof and related compositions and methods of use

    DOEpatents

    Nie, Shuming; Chan, Warren C. W.; Emory, Stephen

    2007-03-20

    The present invention provides a water-soluble luminescent quantum dot, a biomolecular conjugate thereof and a composition comprising such a quantum dot or conjugate. Additionally, the present invention provides a method of obtaining a luminescent quantum dot, a method of making a biomolecular conjugate thereof, and methods of using a biomolecular conjugate for ultrasensitive nonisotopic detection in vitro and in vivo.

  16. Water-soluble luminescent quantum dots and biomolecular conjugates thereof and related compositions and method of use

    DOEpatents

    Nie, Shuming; Chan, Warren C. W.; Emory, Steven R.

    2002-01-01

    The present invention provides a water-soluble luminescent quantum dot, a biomolecular conjugate thereof and a composition comprising such a quantum dot or conjugate. Additionally, the present invention provides a method of obtaining a luminescent quantum dot, a method of making a biomolecular conjugate thereof, and methods of using a biomolecular conjugate for ultrasensitive nonisotopic detection in vitro and in vivo.

  17. Single photon emission from site-controlled InGaN/GaN quantum dots

    SciTech Connect

    Zhang, Lei; Hill, Tyler A.; Deng, Hui; Teng, Chu-Hsiang; Lee, Leung-Kway; Ku, Pei-Cheng

    2013-11-04

    Single photon emission was observed from site-controlled InGaN/GaN quantum dots. The single-photon nature of the emission was verified by the second-order correlation function up to 90 K, the highest temperature to date for site-controlled quantum dots. Micro-photoluminescence study on individual quantum dots showed linearly polarized single exciton emission with a lifetime of a few nanoseconds. The dimensions of these quantum dots were well controlled to the precision of state-of-the-art fabrication technologies, as reflected in the uniformity of their optical properties. The yield of optically active quantum dots was greater than 90%, among which 13%–25% exhibited single photon emission at 10 K.

  18. Engineering the hole confinement for CdTe-based quantum dot molecules

    SciTech Connect

    Kłopotowski, Ł. Wojnar, P.; Kret, S.; Fronc, K.; Wojtowicz, T.; Karczewski, G.

    2015-06-14

    We demonstrate an efficient method to engineer the quantum confinement in a system of two quantum dots grown in a vertical stack. We achieve this by using materials with a different lattice constant for the growth of the outer and inner barriers. We monitor the resulting dot morphology with transmission electron microscopy studies and correlate the results with ensemble quantum dot photoluminescence. Furthermore, we embed the double quantum dots into diode structures and study photoluminescence as a function of bias voltage. We show that in properly engineered structures, it is possible to achieve a resonance of the hole states by tuning the energy levels with electric field. At the resonance, we observe signatures of a formation of a molecular state, hybridized over the two dots.

  19. Phonon bottleneck in p-type Ge/Si quantum dots

    SciTech Connect

    Yakimov, A. I.; Kirienko, V. V.; Armbrister, V. A.; Bloshkin, A. A.; Dvurechenskii, A. V.

    2015-11-23

    We study the effect of quantum dot size on the mid-infrared photo- and dark current, photoconductive gain, and hole capture probability in ten-period p-type Ge/Si quantum dot heterostructures. The dot dimensions are varied by changing the Ge coverage and the growth temperature during molecular beam epitaxy of Ge/Si(001) system in the Stranski-Krastanov growth mode. In all samples, we observed the general tendency: with decreasing the size of the dots, the dark current and hole capture probability are reduced, while the photoconductive gain and photoresponse are enhanced. Suppression of the hole capture probability in small-sized quantum dots is attributed to a quenched electron-phonon scattering due to phonon bottleneck.

  20. Formation of strain-induced quantum dots in gated semiconductor nanostructures

    SciTech Connect

    Thorbeck, Ted; Zimmerman, Neil M.

    2015-08-15

    A long-standing mystery in the field of semiconductor quantum dots (QDs) is: Why are there so many unintentional dots (also known as disorder dots) which are neither expected nor controllable. It is typically assumed that these unintentional dots are due to charged defects, however the frequency and predictability of the location of the unintentional QDs suggests there might be additional mechanisms causing the unintentional QDs besides charged defects. We show that the typical strains in a semiconductor nanostructure from metal gates are large enough to create strain-induced quantum dots. We simulate a commonly used QD device architecture, metal gates on bulk silicon, and show the formation of strain-induced QDs. The strain-induced QD can be eliminated by replacing the metal gates with poly-silicon gates. Thus strain can be as important as electrostatics to QD device operation operation.

  1. Charge-transfer dynamics in multilayered PbS and PbSe quantum dot architectures

    SciTech Connect

    Xu, F.; Ma, X.; Haughn, C. R.; Doty, M. F.; Cloutier, S. G.

    2014-02-03

    We demonstrate control of the charge transfer process in PbS and PbSe quantum dot assemblies. We first demonstrate efficient charge transfer from donor quantum dots to acceptor quantum dots in a multi-layer PbSe cascade structure. Then, we assemble type-I and type-II heterostructures using both PbS and PbSe quantum dots via careful control of the band alignment. In type-I structures, photo-generated carriers are transferred and localized in the smaller bandgap (acceptor) quantum dots, resulting in a significant luminescence enhancement. In contrast, a significant luminescence quenching and shorter emission lifetime confirms an efficient separation of photo-generated carriers in the type-II architecture.

  2. Intermediate-band photosensitive device with quantum dots embedded in energy fence barrier

    DOEpatents

    Forrest, Stephen R.; Wei, Guodan

    2010-07-06

    A plurality of layers of a first semiconductor material and a plurality of dots-in-a-fence barriers disposed in a stack between a first electrode and a second electrode. Each dots-in-a-fence barrier consists essentially of a plurality of quantum dots of a second semiconductor material embedded between and in direct contact with two layers of a third semiconductor material. Wave functions of the quantum dots overlap as at least one intermediate band. The layers of the third semiconductor material are arranged as tunneling barriers to require a first electron and/or a first hole in a layer of the first material to perform quantum mechanical tunneling to reach the second material within a respective quantum dot, and to require a second electron and/or a second hole in a layer of the first semiconductor material to perform quantum mechanical tunneling to reach another layer of the first semiconductor material.

  3. Analysis Insights, August 2015: Sustainable Transportation; NREL (National Renewable Energy Laboratory)

    SciTech Connect

    2015-08-01

    NREL Analysis Insights mines our body of analysis work to synthesize topical insights and key findings. In this issue, we examine transportation systems, alternative fuels, and implications of increasing electrification of transit. Moving people and goods from point A to B has never been easier, but our current transportation systems also take a toll on our environment. Transportation currently accounts for 71% of total U.S. petroleum use and 33% of the nation’s total carbon emissions. With new technology, can we make our transportation system cleaner and more cost effective? NREL is applying its analytical expertise and imagination to do just that. Solutions start with systems thinking. Connecting the dots between physical components - vehicles, fueling stations, and highways - and institutional components - traffic laws, regulations, and vehicle standards - helps illuminate solutions that address the needs of the transportation system's many stakeholders.

  4. Transportation Organization and Functions

    Energy.gov [DOE]

    Office of Packaging and Transportation list of organizations and functions, with a list of acronyms.

  5. Colloidal quantum dot solar cells on curved and flexible substrates

    SciTech Connect

    Kramer, Illan J.; Moreno-Bautista, Gabriel; Minor, James C.; Kopilovic, Damir; Sargent, Edward H.

    2014-10-20

    Colloidal quantum dots (CQDs) are semiconductor nanocrystals synthesized with, processed in, and deposited from the solution phase, potentially enabling low-cost, facile manufacture of solar cells. Unfortunately, CQD solar cell reports, until now, have only explored batch-processing methods—such as spin-coating—that offer limited capacity for scaling. Spray-coating could offer a means of producing uniform colloidal quantum dot films that yield high-quality devices. Here, we explore the versatility of the spray-coating method by producing CQD solar cells in a variety of previously unexplored substrate arrangements. The potential transferability of the spray-coating method to a roll-to-roll manufacturing process was tested by spray-coating the CQD active layer onto six substrates mounted on a rapidly rotating drum, yielding devices with an average power conversion efficiency of 6.7%. We further tested the manufacturability of the process by endeavoring to spray onto flexible substrates, only to find that spraying while the substrate was flexed was crucial to achieving champion performance of 7.2% without compromise to open-circuit voltage. Having deposited onto a substrate with one axis of curvature, we then built our CQD solar cells onto a spherical lens substrate having two axes of curvature resulting in a 5% efficient device. These results show that CQDs deposited using our spraying method can be integrated to large-area manufacturing processes and can be used to make solar cells on unconventional shapes.

  6. LANL, LLNL researchers among Early Career Research Program award...

    National Nuclear Security Administration (NNSA)

    Program awards for 2013. LLNL physicist Yuan Ping's project, selected by the Office of Fusion Research, aims to provide high quality data on critical energy transport properties of...

  7. Supernova Simulations with Boltzmann Neutrino Transport: A Comparison of Methods

    SciTech Connect

    Liebendoerfer, M.; Rampp, M.; Janka, H.-Th.; Mezzacappa, Anthony

    2005-02-01

    Accurate neutrino transport has been built into spherically symmetric simulations of stellar core collapse and postbounce evolution. The results of such simulations agree that spherically symmetric models with standard microphysical input fail to explode by the delayed, neutrino-driven mechanism. Independent groups implemented fundamentally different numerical methods to tackle the Boltzmann neutrino transport equation. Here we present a direct and detailed comparison of such neutrino radiation-hydrodynamics simulations for two codes, AGILE-BOLTZTRAN of the Oak Ridge-Basel group and VERTEX of the Garching group. The former solves the Boltzmann equation directly by an implicit, general relativistic discrete-angle method on the adaptive grid of a conservative implicit hydrodynamics code with second-order TVD advection. In contrast, the latter couples a variable Eddington factor technique with an explicit, moving-grid, conservative high-order Riemann solver with important relativistic effects treated by an effective gravitational potential. The presented study is meant to test our neutrino radiation-hydrodynamics implementations and to provide a data basis for comparisons and verifications of supernova codes to be developed in the future. Results are discussed for simulations of the core collapse and postbounce evolution of a 13 M{sub {circle_dot}} star with Newtonian gravity and a 15 M{sub {circle_dot}} star with relativistic gravity.

  8. Effect of the length of ligands passivating quantum dots on the electrooptical characteristics of organic light-emitting diodes

    SciTech Connect

    Kurochkin, N. S.; Vashchenko, A. A. Vitukhnovsky, A. G.; Tananaev, P. N.

    2015-07-15

    The electrooptical characteristics of organic light-emitting diodes with quantum dots passivated with organic ligands of different lengths as emitting centers are investigated. It is established that the thickness of the ligand coating covering the quantum dots has little effect on the Förster energy transfer in the diodes, but significantly affects the direct injection of charge carriers into the quantum-dot layer. It is shown that the thickness of the passivation coating covering the quantum dots in a close-packed nanoparticle layer is deter- mined both by the length of passivating ligands and the degree of quantum-dot coverage with ligands.

  9. Research Highlight

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Pollution Hitches Ride to Arctic Download a printable PDF Submitter: Zelenyuk-Imre, A., Pacific Northwest National Laboratory Area of Research: Aerosol Properties Working Group(s): Aerosol Life Cycle Journal Reference: Zelenyuk A, D Imre, J Beranek, E Abramson, J Wilson, and M Shrivastava. 2012. "Synergy between secondary organic aerosols and long-range transport of polycyclic aromatic hydrocarbons." Environmental Science & Technology, 46(22), doi:10.1021/es302743z. When airborne

  10. Research Highlight

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Profiling Capability of High-Resolution Oxygen A-band Spectroscopy for Stratus Cloud Cover Submitter: Davis, A. B., Jet Propulsion Laboratory Area of Research: Cloud Distributions/Characterizations Working Group(s): Cloud Properties Journal Reference: Davis AB, IN Polonsky, and A Marshak. 2009. Space-Time Green Functions for Diffusive Radiation Transport, in Application to Active and Passive Cloud Probing. In Light Scattering Reviews, Volume 4, pp. 169-292. Ed. by A.A. Kohkanovsky, Heidelberg,

  11. Transportation technology R&D-Steve Ciatti | Argonne National...

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    technology R&D-Steve Ciatti Share Description Argonne researcher Steve Ciatti talks about emerging technologies in transportation, as well as the current technology being developed...

  12. National Alliance for Advanced Transportation Battery Cell Manufacture...

    OpenEI (Open Energy Information) [EERE & EIA]

    Manufacture Product: US-based consortium formed to research, develop, and mass produce lithium ion batteries. References: National Alliance for Advanced Transportation Battery Cell...

  13. Transportation technology R&D—Steve Ciatti

    ScienceCinema

    Steve Ciatti

    2016-07-12

    Argonne researcher Steve Ciatti talks about the emerging technologies in transportation, as well as the current technology being developed at the lab and placed on the market.

  14. Influence of Topological Spin Fluctuations on Charge Transport

    U.S. Department of Energy (DOE) - all webpages (Extended Search)

    Influence of Topological Spin Fluctuations on Charge Transport Print Layered transition metal oxides are the focus of intense research efforts because they might clarify the...

  15. Transport and Phase Equilibria Properties for Steam Flooding...

    Office of Scientific and Technical Information (OSTI)

    The objectives of this research included experimental determination and rigorous modeling and computation of phase equilibrium diagrams, volumetric, and transport properties of ...

  16. Nonlinear transport in ionic liquid gated strontium titanate nanowires

    SciTech Connect

    Bretz-Sullivan, Terence M.; Goldman, A. M.

    2015-09-14

    Measurements of the current-voltage (I–V) characteristics of ionic liquid gated nanometer scale channels of strontium titanate have been carried out. At low gate voltages, the I–V characteristics exhibit a large voltage threshold for conduction and a nonlinear power law behavior at all temperatures measured. The source-drain current of these nanowires scales as a power law of the difference between the source-drain voltage and the threshold voltage. The scaling behavior of the I–V characteristic is reminiscent of collective electronic transport through an array of quantum dots. At large gate voltages, the narrow channel acts as a quasi-1D wire whose conductance follows Landauer's formula for multichannel transport.

  17. Interagency cooperation in the development of a cost-effective transportation and disposal solution for vitrified radium bearing material

    SciTech Connect

    Smith, M.L.; Nixon, D.A.; Stone, T.J.; Tope, W.G.; Vogel, R.A.; Allen, R.B.; Schofield, W.D.

    1996-02-01

    Fernald radium bearing ore residue waste, stored within Silos 1 and 2 (K-65) and Silo 3 waste, will be vitrified for disposal at the Nevada Test Site (NTS). A comprehensive, parametric evaluation of waste form, shielding requirements, packaging, and transportation alternatives was completed to identify the safest, most cost-effective approach. The impacts of waste loading, waste form, regulatory requirements, NTS waste acceptance criteria, as-low-as-resonably-achievable principles, and material handling costs were factored into the recommended approach. Through cooperative work between the U.S. Department of Energy (DOE) and the U.S. Department of Transportation (DOT), the vitrified K-65 and Silo 3 radioactive material will be classified consistent with the regulations promulgated by DOT in the September 28, 1995 Federal Register. These new regulations adopt International Atomic Energy Agency language to promote a consistent approach for the transportation and management of radioactive material between the international community and the DOT. Use of the new regulations allows classification of the vitrified radioactive material from the Fernald silos under the designation of low specific activity-II and allows the development of a container that is optimized to maximize payload while minimizing internal void space, external surface radiation levels, and external volume. This approach minimizes the required number of containers and shipments, and the related transportation and disposal costs.

  18. Effect of swift heavy ion irradiation on bare and coated ZnS quantum dots

    SciTech Connect

    Chowdhury, S. Hussain, A.M.P.; Ahmed, G.A.; Singh, F.; Avasthi, D.K.; Choudhury, A.

    2008-12-01

    The present study compares structural and optical modifications of bare and silica (SiO{sub 2}) coated ZnS quantum dots under swift heavy ion (SHI) irradiation. Bare and silica coated ZnS quantum dots were prepared following an inexpensive chemical route using polyvinyl alcohol (PVA) as the dielectric host matrix. X-ray diffraction (XRD) and transmission electron microscopy (TEM) study of the samples show the formation of almost spherical ZnS quantum dots. The UV-Vis absorption spectra reveal blue shift relative to bulk material in absorption energy while photoluminescence (PL) spectra suggests that surface state and near band edge emissions are dominating in case of bare and coated samples, respectively. Swift heavy ion irradiation of the samples was carried out with 160 MeV Ni{sup 12+} ion beam with fluences 10{sup 12} to 10{sup 13} ions/cm{sup 2}. Size enhancement of bare quantum dots after irradiation has been indicated in XRD and TEM analysis of the samples which has also been supported by optical absorption spectra. However similar investigations on irradiated coated quantum dots revealed little change in quantum dot size and emission. The present study thus shows that the coated ZnS quantum dots are stable upon SHI irradiation compared to the bare one.

  19. Tuning the properties of Ge-quantum dots superlattices in amorphous silica matrix through deposition conditions

    SciTech Connect

    Pinto, S. R. C.; Ramos, M. M. D.; Gomes, M. J. M.; Buljan, M.; Chahboun, A.; Roldan, M. A.; Molina, S. I.; Bernstorff, S.; Varela, M.; Pennycook, S. J.; Barradas, N. P.; Alves, E.

    2012-04-01

    In this work, we investigate the structural properties of Ge quantum dot lattices in amorphous silica matrix, prepared by low-temperature magnetron sputtering deposition of (Ge+SiO{sub 2})/SiO{sub 2} multilayers. The dependence of quantum dot shape, size, separation, and arrangement type on the Ge-rich (Ge + SiO{sub 2}) layer thickness is studied. We show that the quantum dots are elongated along the growth direction, perpendicular to the multilayer surface. The size of the quantum dots and their separation along the growth direction can be tuned by changing the Ge-rich layer thickness. The average value of the quantum dots size along the lateral (in-plane) direction along with their lateral separation is not affected by the thickness of the Ge-rich layer. However, the thickness of the Ge-rich layer significantly affects the quantum dot ordering. In addition, we investigate the dependence of the multilayer average atomic composition and also the quantum dot crystalline quality on the deposition parameters.

  20. Enhanced performance of branched TiO{sub 2} nanorod based Mn-doped CdS and Mn-doped CdSe quantum dot-sensitized solar cell

    SciTech Connect

    Kim, Soo-Kyoung; Gopi, Chandu V. V. M.; Lee, Jae-Cheol; Kim, Hee-Je

    2015-04-28

    TiO{sub 2} branched nanostructures could be efficient as photoanodes for quantum dot-sensitized solar cells (QDSCs) due to their large surface area for QD deposition. In this study, Mn-doped CdS/Mn-doped CdSe deposited branched TiO{sub 2} nanorods were fabricated to enhance the photovoltaic performance of QDSCs. Mn doping in CdS and CdSe retards the recombination losses of electrons, while branched TiO{sub 2} nanorods facilitate effective electron transport and compensate for the low surface area of the nanorod structure. As a result, the charge-transfer resistance (R{sub CT}), electron lifetime (?{sub e}), and the amount of QD deposition were significantly improved with branched TiO{sub 2} nanorod based Mn-doped CdS/Mn-doped CdSe quantum dot-sensitized solar cell.