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Title: Low-frequency dynamics of CO/Cu breakdown of Born--Oppenheimer approximation

Abstract

Synchrotron infrared studies of adsorbates on surfaces offer the possibility of probing low-frequency vibrational modes and dynamics at high resolution (1 cm[sup [minus]1], 125 [mu]eV). Extensive experiments have been performed for ordered submonolayers of CO on low index Cu surfaces [([radical]3[times][radical]3)[ital R]30[degree] CO/Cu(111), [ital c](2[times]2) CO/Cu(100) and (1[times]2) CO/Cu(110)], in the 100--2500 cm[sup [minus]1] ([similar to]12.5--312.5 meV) range. These are the first IR experiments to directly probe the adsorbate-substrate vibrations for this system. In addition, however, several surprising features are observed including the dipole-forbidden hindered rotation and an unexpected broadband absorption. Two theories have been motivated by this work, and will be compared to our experimental results. The first theory is a cluster calculation by Tully, Gomez, and Head-Gordon, which takes into account the breakdown of the Born--Oppenheimer approximation and predicts lifetimes and frequencies of the vibrational modes for CO/Cu(100). Another Drude-based theory, proposed by Persson, considers the coupling of the conduction electron current to the vibrations of the adsorbates, accounting for the observation of both the broadband absorption and dipole-forbidden peak.

Authors:
 [1];  [2];  [3];  [4]
  1. Yale University, New Haven, Connecticut 06520 (United States) NSLS, Brookhaven National Laboratory, Upton, New York 11973 (United States)
  2. AT T Bell Labs, Murray Hill, New Jersey 07974 (United States)
  3. EXXON Research and Engineering, Annandale, New Jersey 08801 (United States)
  4. NSLS, Brookhaven National Laboratory, Upton, New York 11973 (United States)
Publication Date:
OSTI Identifier:
7084995
DOE Contract Number:  
AC02-76CH00016
Resource Type:
Journal Article
Journal Name:
Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (United States)
Additional Journal Information:
Journal Volume: 12:4; Journal ID: ISSN 0734-2101
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CARBON MONOXIDE; ADSORPTION; COPPER; SORPTIVE PROPERTIES; ABSORPTION SPECTRA; BORN-OPPENHEIMER APPROXIMATION; INFRARED RADIATION; SYNCHROTRON RADIATION; VIBRATIONAL STATES; BREMSSTRAHLUNG; CARBON COMPOUNDS; CARBON OXIDES; CHALCOGENIDES; ELECTROMAGNETIC RADIATION; ELEMENTS; ENERGY LEVELS; EXCITED STATES; METALS; OXIDES; OXYGEN COMPOUNDS; RADIATIONS; SORPTION; SPECTRA; SURFACE PROPERTIES; TRANSITION ELEMENTS; 360606* - Other Materials- Physical Properties- (1992-)

Citation Formats

Hirschmugl, C J, Chabal, Y J, Hoffmann, F M, and Williams, G P. Low-frequency dynamics of CO/Cu breakdown of Born--Oppenheimer approximation. United States: N. p., 1994. Web. doi:10.1116/1.579120.
Hirschmugl, C J, Chabal, Y J, Hoffmann, F M, & Williams, G P. Low-frequency dynamics of CO/Cu breakdown of Born--Oppenheimer approximation. United States. https://doi.org/10.1116/1.579120
Hirschmugl, C J, Chabal, Y J, Hoffmann, F M, and Williams, G P. 1994. "Low-frequency dynamics of CO/Cu breakdown of Born--Oppenheimer approximation". United States. https://doi.org/10.1116/1.579120.
@article{osti_7084995,
title = {Low-frequency dynamics of CO/Cu breakdown of Born--Oppenheimer approximation},
author = {Hirschmugl, C J and Chabal, Y J and Hoffmann, F M and Williams, G P},
abstractNote = {Synchrotron infrared studies of adsorbates on surfaces offer the possibility of probing low-frequency vibrational modes and dynamics at high resolution (1 cm[sup [minus]1], 125 [mu]eV). Extensive experiments have been performed for ordered submonolayers of CO on low index Cu surfaces [([radical]3[times][radical]3)[ital R]30[degree] CO/Cu(111), [ital c](2[times]2) CO/Cu(100) and (1[times]2) CO/Cu(110)], in the 100--2500 cm[sup [minus]1] ([similar to]12.5--312.5 meV) range. These are the first IR experiments to directly probe the adsorbate-substrate vibrations for this system. In addition, however, several surprising features are observed including the dipole-forbidden hindered rotation and an unexpected broadband absorption. Two theories have been motivated by this work, and will be compared to our experimental results. The first theory is a cluster calculation by Tully, Gomez, and Head-Gordon, which takes into account the breakdown of the Born--Oppenheimer approximation and predicts lifetimes and frequencies of the vibrational modes for CO/Cu(100). Another Drude-based theory, proposed by Persson, considers the coupling of the conduction electron current to the vibrations of the adsorbates, accounting for the observation of both the broadband absorption and dipole-forbidden peak.},
doi = {10.1116/1.579120},
url = {https://www.osti.gov/biblio/7084995}, journal = {Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (United States)},
issn = {0734-2101},
number = ,
volume = 12:4,
place = {United States},
year = {Fri Jul 01 00:00:00 EDT 1994},
month = {Fri Jul 01 00:00:00 EDT 1994}
}