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