Elementary surface photo-induced reactions : Study by laser and surface spectroscopy

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Surface photochemistry concerns photoinduced processes at gas-solid interfaces. This year, we have investigated desorption, dissociation, and reaction of adsorbed molecules initiated by ultraviolet photoirradiation. Especially we compare the experimental results between gas- and surface-phase. Since carbon monoxide has been a pet molecule to surface scientists, CO was detected by laser-induced fluorescence technique, which came from the 230 nm photodissociation of OCS.Our results are different from those reported by our counter scientist Prof.Houston of Cornell Univcersity. Based on discussion, our conclusion is that a) we have to determine the electronic state and molecular structure of the photoprepared OCS,and b) photodissociation of OCS adsorbed on a surface will be helpful to interpret the discrepancy between our and their results. In Hokkaido, we have constructed a surface photodissociation machine to continue the OCS photodissociation. In cooperation with Prof. Ho of Cornell University, we have studied photoirradiation effect on Cl-atom-etched GaAs substrates and found significant wavelength effect.