抄録
Photo-induced desorption of molecules from metal surfaces is discussed. First, we present potential energy surfaces as a function of the distance between the adsorbate and the surface for CO and NO on Pt, which have been calculated using three-atom clusters to model the chemisorption systems, and discuss the desorption processes in terms of the Menzel-Gomer-Redhead (MGR) model. In the MGR model, the initial excitation by photons is assumed to be localized around the adsorbate, but a calculation with an extended slab to represent CO/Pt(111) suggests that states derived from the adsorbates are extended over the substrate, implying that this assumption is not always valid. A desorption mechanism via the nonadiabatic coupling is then illustrated that describes desorption processes in which the initial excitation is extended over the substrate. Finally, several important issues remaining to be solved are presented.
