title: Ultrafast laser excitation of CO/Pt(111) probed by sum frequency generation: coverage dependent desorption efficiency.
abstract: CO photodesorption from Pt(111) induced by femtosecond laser pulses is probed by IR+visible sum frequency generation (SFG). Steady state analysis of SFG spectra at varying CO pressure and laser fluence allows one to measure a approximately 5 orders of magnitude decrease of the photodesorption rate constant when CO coverage decreases from 0.37 to 0.07 monolayer. We ascribe this effect in the framework of the Menzel-Gomer-Redhead mechanism to electron delocalization in the CO layer. The lifetime of electronic excitation decreases when coverage decreases.
authors.affiliation: Laboratoire de Photophysique Moléculaire, CNRS, Bâtiment 210, Université de Paris-Sud, 91405 Orsay Cedex, France.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Fournier
authors.forename: Wanquan
authors.initials: W
authors.lastname: Zheng
authors.forename: Serge
authors.initials: S
authors.lastname: Carrez
authors.forename: Henri
authors.initials: H
authors.lastname: Dubost
authors.forename: Bernard
authors.initials: B
authors.lastname: Bourguignon