Ultrafast laser excitation of CO/Pt(111) probed by sum frequency generation: coverage dependent desorption efficiency.
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.
Fournier
Frédéric
F
Laboratoire de Photophysique Moléculaire, CNRS, Bâtiment 210, Université de Paris-Sud, 91405 Orsay Cedex, France.
Zheng
Wanquan
W
Carrez
Serge
S
Dubost
Henri
H
Bourguignon
Bernard
B