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Title: Coverage dependent non-adiabaticity of CO on a copper surface

We have studied the coverage-dependent energy transfer dynamics between hot electrons and CO on Cu(110) with femtosecond visible pump, sum frequency probe spectroscopy. We find that transients of the Cā€“O stretch frequency display a red shift, which increases from 3 cm{sup āˆ’1} at 0.1 ML to 9 cm{sup āˆ’1} at 0.77 ML. Analysis of the transients reveals that the non-adiabatic coupling between the adsorbate vibrational motion and the electrons becomes stronger with increasing coverage. This trend requires the frustrated rotational mode to be the cause of the non-adiabatic behavior, even for relatively weak laser excitation of the adsorbate. We attribute the coverage dependence to both an increase in the adsorbate electronic density of states and an increasingly anharmonic potential energy surface caused by repulsive interactions between neighboring CO adsorbates. This work thus reveals adsorbate-adsorbate interactions as a new way to control adsorbate non-adiabaticity.
Authors:
 [1] ;  [2] ;  [1]
  1. Surface Science Research Centre, University of Liverpool, Oxford Road, Liverpool L69 3BX (United Kingdom)
  2. (Japan)
Publication Date:
OSTI Identifier:
22413279
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 141; Journal Issue: 21; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CARBON MONOXIDE; COPPER; DENSITY OF STATES; ELECTRONS; ENERGY TRANSFER; EXCITATION; INTERACTIONS; SPECTROSCOPY; SURFACES; TRANSIENTS