Ag loaded Ga2O3 (Ag/Ga2O3) photocatalysts were prepared by an impregnation method, and examined for photocatalytic reduction of CO2 with water where CO, H2 and O2 were formed as products. TEM and X-ray absorption near edge structure (XANES) measurements revealed that around 1 nm sized Ag clusters were formed predominantly in an active Ag/Ga2O3 sample while partially oxidized large Ag particles with the size of several -several tens nm were observed in a less active Ag/Ga2O3 samples. Both Ag L3-edge and O K-edge XANES analysis suggested that the small Ag clusters accepted more electrons in the d-orbitals as the result of the strong interaction with the Ga2O3 surface. In-situ FT-IR measurements for the Ag/Ga2O3 samples showed CO3 stretching vibration bands assignable to monodentate bicarbonate and bidentate carbonate species chemisorbed on the Ga2O3 surface, and to monodentate carbonate species on the large Ag particles. Among these chemisorbed species, the monodentate bicarbonate and/or the bidentate carbonate species changed to bidentate formate species, as the reaction intermediate, under the UV light irradiation. The bidentate formate species was formed not by the plasmonic excitation of the Ag nanoparticles but by the photoexcitation of the Ga2O3 semiconductor, and the formation process would be promoted at the perimeter of the Ag clusters on the Ga2O3 surface by the effective separation of electronholes pairs. Catalysts preparation.Ag/Ga 2 O 3 samples were prepared by an impregnation method. A mixture of a Ga 2 O 3 powder (Kojundo Chemical Laboratory Co. Ltd. purity 99.99 %) and an aqueous solution of AgNO 3 (Kishida Chemical Co. Ltd. purity 99.8 %) was magnetically stirred and dried up, followed by calcination at 673 K for 2 h, which provided the Ag/Ga 2 O 3 samples. The loading amounts of Ag were 0.1, 0.2, 0.5 and 1.0 wt%.

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A size and condensation controlled Pd nanoparticle is reported. The Pd nanoparticles are prepared by a gas condensation method with He gas, so called dry process. A fabrication of the nanoparticle by means of the dry process is an excellent way, because there are little contaminations on the most lateral surface of the nanoparticle than the nanoparticle by the wet process. Characterizations by TEM and AFM show that the fabricated Pd nanoparticle has a spherical shape, a few nm size in diameter and highly dispersed on the substrate. It is found that there are two chemical states in the Pd nanoparticle. One is an oxidized part at the surface and the other is a bulk part.

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The evolution of silicon carbide ͑0001͒ surface reconstruction upon annealing has been studied by Si K-edge near-edge x-ray-absorption fine structure ͑NEXAFS͒. With the increase in annealing temperature, the fluorescence yield of Si K-edge NEXAFS clearly indicates an increase in disorder of Si atoms in the much deeper interior beneath the surface due to out diffusion of Si atoms to the surface forming increased Si vacancies. The concentration of Si vacancies beneath the epitaxial graphene formed by high-temperature annealing of SiC is estimated to be as high as 15% to a depth of several micrometers. As acceptors in SiC, the high concentration of Si vacancies could have a significant impact on the electronic properties of epitaxial graphene by chargetransfer doping from the substrate and the introduction of interface states.