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Title: Revealing Nanoscale Energy Flow Using Ultrafast THz to X-ray Beams (Final Technical Report)

Abstract

We developed novel spectroscopic methods and made use of them to study energy flow and material properties on nanometer length scales and ultrafast time scales. Access to short length scales was provided through the use of light beams with short wavelengths (EUV through hard x-ray spectral ranges) and/or fabricated structural elements with nanometer dimensions. Recent advances in tabletop high harmonic generation of extreme ultraviolet (EUV) pulses were exploited to measure thermal transport and acoustic vibrations using time-resolved diffraction from photoexcited periodic nanostructures, revealing new physics that arises at length scales of tens to hundreds of nm. The tabletop EUV sources as well as the FERMI free electron laser at FERMI-Elettra in Trieste were used to generate as well as measure nanoscale thermoelastic responses without the need for patterned nanostructures, with the short length scale coming from optical interference patterns formed by crossing pairs of beams in transient grating experiments. We also used EUV and optical sources to excite and monitor ultrahigh-frequency acoustic waves (coherent phonons) at ultraflat interfaces and multilayer structures, extending our measurements of the highest-frequency coherent acoustic waves observed to date. Our measurements of acoustic properties allowed direct calculation of thermal conductivities which can be compared with ourmore » measurements of thermal transport and with first-principles calculations. Terahertz-frequency acoustic measurements can also be used to reveal complex relaxation dynamics in glass-forming liquids and partially disordered solids. Acoustic measurements were used to investigate the confinement effect in ultrathin liquid layers and to characterize mechanical properties of ultrathin solid layers. The methods we developed have broad fundamental applications and may also enable new practical metrology for use in nanoelectronics, just as earlier methods we developed have found commercial applications in microelectronics metrology.« less

Authors:
 [1];  [2]
  1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  2. Univ. of Colorado, Boulder, CO (United States); National Inst. of Standards and Technology (NIST), Boulder, CO (United States)
Publication Date:
Research Org.:
Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1527143
Report Number(s):
Final_Technical_Report
DOE Contract Number:  
FG02-00ER15087
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English

Citation Formats

Nelson, Keith A., and Murnane, Margaret M. Revealing Nanoscale Energy Flow Using Ultrafast THz to X-ray Beams (Final Technical Report). United States: N. p., 2019. Web. doi:10.2172/1527143.
Nelson, Keith A., & Murnane, Margaret M. Revealing Nanoscale Energy Flow Using Ultrafast THz to X-ray Beams (Final Technical Report). United States. doi:10.2172/1527143.
Nelson, Keith A., and Murnane, Margaret M. Thu . "Revealing Nanoscale Energy Flow Using Ultrafast THz to X-ray Beams (Final Technical Report)". United States. doi:10.2172/1527143. https://www.osti.gov/servlets/purl/1527143.
@article{osti_1527143,
title = {Revealing Nanoscale Energy Flow Using Ultrafast THz to X-ray Beams (Final Technical Report)},
author = {Nelson, Keith A. and Murnane, Margaret M.},
abstractNote = {We developed novel spectroscopic methods and made use of them to study energy flow and material properties on nanometer length scales and ultrafast time scales. Access to short length scales was provided through the use of light beams with short wavelengths (EUV through hard x-ray spectral ranges) and/or fabricated structural elements with nanometer dimensions. Recent advances in tabletop high harmonic generation of extreme ultraviolet (EUV) pulses were exploited to measure thermal transport and acoustic vibrations using time-resolved diffraction from photoexcited periodic nanostructures, revealing new physics that arises at length scales of tens to hundreds of nm. The tabletop EUV sources as well as the FERMI free electron laser at FERMI-Elettra in Trieste were used to generate as well as measure nanoscale thermoelastic responses without the need for patterned nanostructures, with the short length scale coming from optical interference patterns formed by crossing pairs of beams in transient grating experiments. We also used EUV and optical sources to excite and monitor ultrahigh-frequency acoustic waves (coherent phonons) at ultraflat interfaces and multilayer structures, extending our measurements of the highest-frequency coherent acoustic waves observed to date. Our measurements of acoustic properties allowed direct calculation of thermal conductivities which can be compared with our measurements of thermal transport and with first-principles calculations. Terahertz-frequency acoustic measurements can also be used to reveal complex relaxation dynamics in glass-forming liquids and partially disordered solids. Acoustic measurements were used to investigate the confinement effect in ultrathin liquid layers and to characterize mechanical properties of ultrathin solid layers. The methods we developed have broad fundamental applications and may also enable new practical metrology for use in nanoelectronics, just as earlier methods we developed have found commercial applications in microelectronics metrology.},
doi = {10.2172/1527143},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2019},
month = {6}
}