Infrared response of chemisorbed CO to femtosecond metal substrate heating

Time resolved IR spectroscopy is used to monitor the stretch mode of CO on Cu(111) following femtosecond visible excitation. A time dependent shift in the stretch mode complex frequency is observed and is attributed to low frequency adsorbate-like modes becoming excited via coupling to substrate electrons and phonons. At low levels of excitation it is found that the frustrated translation is coupling to the bulk electron reservoir with a rate (gamma) eequals167(24) GHz, and to the bulk phonon reservoir with a rate (gamma) Lequals145(56) GHz. At higher excitation levels deviations from the model are observed.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.