skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Electron Probes of Nanoscale and Subnanoscale Structures and their Dynamics


Substantial progress was made by these visitors on the subject of electron probes of the dynamics of nanoscale and subnanoscale structures.

  1. Univ. of California, Irvine, CA (United States)
Publication Date:
Research Org.:
Univ. of California, Irvine, CA (United States)
Sponsoring Org.:
OSTI Identifier:
Report Number(s):
DOE Contract Number:
Resource Type:
Technical Report
Country of Publication:
United States

Citation Formats

White, Steven. Electron Probes of Nanoscale and Subnanoscale Structures and their Dynamics. United States: N. p., 2015. Web. doi:10.2172/1169304.
White, Steven. Electron Probes of Nanoscale and Subnanoscale Structures and their Dynamics. United States. doi:10.2172/1169304.
White, Steven. 2015. "Electron Probes of Nanoscale and Subnanoscale Structures and their Dynamics". United States. doi:10.2172/1169304.
title = {Electron Probes of Nanoscale and Subnanoscale Structures and their Dynamics},
author = {White, Steven},
abstractNote = {Substantial progress was made by these visitors on the subject of electron probes of the dynamics of nanoscale and subnanoscale structures.},
doi = {10.2172/1169304},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2015,
month = 2

Technical Report:

Save / Share:
  • Dominant research results on adsorption on gold clusters are reviewed, including adsorption of H{sub 2}O and O{sub 2} on gold cluster cations and anions, kinetics of CO adsorption to middle sized gold cluster cations, adsorption of CO on Au{sub n}{sup +} with induced changes in structure, and H{sub 2}O enhancement of CO adsorption.
  • The inability to remove heat efficiently is currently one of the stumbling blocks toward further miniaturization and advancement of electronic, optoelectronic, and micro-electro-mechanical devices. In order to formulate better heat removal strategies and designs, it is first necessary to understand the fundamental mechanisms of heat transport in semiconductor thin films. Modeling techniques, based on first principles, can play the crucial role of filling gaps in our understanding by revealing information that experiments are incapable of. Heat conduction in crystalline semiconductor films occurs by lattice vibrations that result in the propagation of quanta of energy called phonons. If the mean freemore » path of the traveling phonons is larger than the film thickness, thermodynamic equilibrium ceases to exist, and thus, the Fourier law of heat conduction is invalid. In this scenario, bulk thermal conductivity values, which are experimentally determined by inversion of the Fourier law itself, cannot be used for analysis. The Boltzmann Transport Equation (BTE) is a powerful tool to treat non-equilibrium heat transport in thin films. The BTE describes the evolution of the number density (or energy) distribution for phonons as a result of transport (or drift) and inter-phonon collisions. Drift causes the phonon energy distribution to deviate from equilibrium, while collisions tend to restore equilibrium. Prior to solution of the BTE, it is necessary to compute the lifetimes (or scattering rates) for phonons of all wave-vector and polarization. The lifetime of a phonon is the net result of its collisions with other phonons, which in turn is governed by the conservation of energy and momentum during the underlying collision processes. This research project contributed to the state-of-the-art in two ways: (1) by developing and demonstrating a calibration-free simple methodology to compute intrinsic phonon scattering (Normal and Umklapp processes) time scales with the inclusion of optical phonons, and (2) by developing a suite of numerical algorithms for solution of the BTE for phonons. The suite of numerical algorithms includes Monte Carlo techniques and deterministic techniques based on the Discrete Ordinates Method and the Ballistic-Diffusive approximation of the BTE. These methods were applied to calculation of thermal conductivity of silicon thin films, and to simulate heat conduction in multi-dimensional structures. In addition, thermal transport in silicon nanowires was investigated using two different first principles methods. One was to apply the Green-Kubo formulation to an equilibrium system. The other was to use Non-Equilibrium Molecular Dynamics (NEMD). Results of MD simulations showed that the nanowire cross-sectional shape and size significantly affects the thermal conductivity, as has been found experimentally. In summary, the project clarified the role of various phonon modes - in particular, optical phonon - in non-equilibrium transport in silicon. It laid the foundation for the solution of the BTE in complex three-dimensional structures using deterministic techniques, paving the way for the development of robust numerical tools that could be coupled to existing device simulation tools to enable coupled electro-thermal modeling of practical electronic/optoelectronic devices. Finally, it shed light on why the thermal conductivity of silicon nanowires is so sensitive to its cross-sectional shape.« less
  • Sequence-specific polymers are the basis of the most promising approaches to bottom-up programmed assembly of nanoscale materials. Examples include artificial peptides and nucleic acids. Another class is oligo(N-functional glycine)s, also known as peptoids, which permit greater sidegroup diversity and conformational control, and can be easier to synthesize and purify. We have developed a set of peptoids that can be used to make inorganic nanoparticles more compatible with biological sequence-specific polymers so that they can be incorporated into nucleic acid or other biologically based nanostructures. Peptoids offer degrees of modularity, versatility, and predictability that equal or exceed other sequence-specific polymers, allowingmore » for rational design of oligomers for a specific purpose. This degree of control will be essential to the development of arbitrarily designed nanoscale structures.« less
  • Our efforts in the past three and a half years have been directed towards providing the ground work for applying REMPI detection to the dynamics of surface oxidation and desorption reactions. Our initial efforts addressed the oxidation of carbon films that had been prepared on metal supports. The photolysis of adsorbed N{sub 2}O was chosen as the initial oxygen atom source. However, a number of alternative O atom precursors were also evaluated. Results from Auger electron spectroscopy (AES), temperature programmed desorption (TPD), and state-resolved studies of the photochemistry of N{sub 2}O, NO{sub 2}, or O{sub 2} coadsorbed with carbon onmore » Pt(111) have been obtained. In the last eighteen months, we have focused on a stringent test of current theories of femtosecond laser-induced desorption of CO/Cu(100). The results indicate that an electronic friction model is sufficient to account for essentially all of the results in this system, indicating that a predictive tool for femtosecond laser-induced surface chemistry may be in hand.« less