Dynamics of Phdto stimulated Desorption from Solid Surfaces

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Photo-stimulated desorption from solid surfaces has been investigated by the main use of electron-ion coincidence spectroscopy combined with the synchrotron radiation. Results are as follows;1. The site-specific phenomena, where the excitation on different atoms (including the difference in the chemical environment) caused different bond-breaking, was found. It suggested that the control of the photo-chemical reaction will be possible by using the soft-X-ray, 2. Photo-stimulated desorption induced 9by the metal-core excitation on transition and non-transition metal oxide surfaces has been investigated, and it was found that the conventional KF model was not sufficiently applicable. A new model of the charge transfer (Kotani-Toyozawa mechanism) was proposed for explaining the experimental results, 3. Photo-stimulated desorption induced by the Ols-excitation on the metal oxide surfaces and molecular-adsorbed semiconductor surfaces have been investigated. It was found that the ion desorption took place as a result of the formation of the multiple-hole final state produced by the shake-up/off excitation accompanying the core-excitation and the Auger decay, and 4. Electron-ion coincidence spectroscopy was used for a analysis of the ice surface, and it was shown that this technique can be used as an extremely surface sensitive ESCA.Photoelectron spectroscopy was also used for investigating the decay dynamics of the core-excited state, and 5. It was found that the lifetime of the surface core exciton is longer than that of the bulk one on the Xe film. Moreover, 6. The instrumental system of the time-resolved two-photon photoelectron spectroscopy using the femto-second laser was constructed. The preliminary results are now obtained.