Two-photon photoelectron spectroscopy

Two-photon photoelectron spectroscopy is the method of forming the excited state of surfaces by laser beam irradiation, and observing the photoelectron emission from the excited state with another beam. In this method, the spectrometry of the excited state of valance electrons is the objective, but especially it is the feature that the level localized to surfaces is preferably observed. Since pulsed laser beam is used as the light source, it is also feasible to measure the relaxation process of the excited level by real time. In this paper, the typical examples of the measurement and the excited state of adsorbed molecules are reported. Photoelectron spectroscopy is the technique which is effective for examining the condition of electrons on surfaces, and there is the enormous accumulation of researches on the occupied level, but as for the unoccupied level, there are many undeveloped parts. Two-photon photoelectron spectrometry is the technique for observing the unoccupied level of solid surfaces. Relaxation and photoemission, the mirror image level of metal surfaces, the excitation level of semiconductor surfaces, the two-photon photoelectron spectroscopy of the surfaces, on which molecules were adsorbed, and the copper surface on which NO was adsorbed are reported. (K.I.)