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1.
Tada H Soejima T Ito S Kobayashi H 《Journal of the American Chemical Society》2004,126(49):15952-15953
We now report photoinduced sulfur desorption from the surfaces of Au nanoparticles loaded on metal oxides. This reaction occurs in water at ordinary temperature and pressure. Nanometer-sized Au particles have been formed on the surfaces of various metal oxides by deposition-precipitation (Au/oxides). Elemental sulfur (S8) is selectively adsorbed on the Au nanoparticle surfaces of Au/oxides in an atomic state at a coverage of (theta) = 1/3 and in both atomic and molecular states at theta > 1/3. Irradiation (lambdaex > 300 nm) of the sulfur adsorbed Au/anatase TiO2 in water has led to reductive desorption of the sulfurs at room temperature. Electrochemical measurements using Au/oxides indicate that the driving force for this reaction is the photoinduced upward shift of Fermi energy of the metal oxide-supported Au nanoprticles. This study will open up a novel and wide application of heterogeneous photocatalysis for thermal catalysts. 相似文献
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Using two synchronously pumped dye lasers and a high-frequency lock-in detection system, resonance inverse Raman spectroscopy has been performed in solutions of rhodamine-B. Linear and circular polarization modulation experiments and variation of the Raman band-shape according to the probe frequency tuning are reported. 相似文献
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Using the CARS Maker fringe technique, the nonresonant third-order nonlinear susceptibility was measured in several liquids. 相似文献
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TiO2 nanocrystalline films were prepared from titanium tetra-n-butoxide modified with double hydrolysis inhibitors, acetylacetone and polyethylene glycol (PEG), in mixture of methanol
and ethanol. The correlation among surface structure of the TiO2 films, preparation conditions, and photovoltaic properties of the solar cells using the TiO2 films was investigated. The particle size of the obtained TiO2 films was decreased as the PEG content increased. The nanostructured films with the narrow distribution of particle size
could be prepared. The amounts of adsorbed dyes for these TiO2 films were larger than that without PEG. The performance of the solar cell fabricated using the TiO2 film improved as the amount of the PEG increased, and the solar cell using the TiO2 film prepared from the solution with 30 wt% PEG exhibited the highest performance. 相似文献
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Hiroaki Tada Tetsuji Ishida Ayako Takao Seishiro Ito Sudip Mukhopadhyay Tomoki Akita Koji Tanaka Hisayoshi Kobayashi 《Chemphyschem》2005,6(8):1537-1543
TiO2 particles loaded with silver nanoparticles with a mean diameter of 1.5 nm exhibit a high photocatalytic activity (84 % conversion after 1 h irradiation) for the reduction of nitrobenzene to aniline with 100 % selectivity in the presence of CH3OH (concentration=100 mM). High-resolution transmission electron microscopic studies of Pt-photodeposited Ag/TiO2 demonstrate that the Ag nanoparticles act as reduction sites in the photocatalytic reaction. Both spectroscopic measurements and density functional theory (DFT) calculations reveal that nitrobenzene is selectively adsorbed onto the Ag surfaces of Ag/TiO2 via partial electron transfer from Ag to nitrobenzene, whereas the interaction between aniline and Ag/TiO2 is weak. The kinetic analysis indicates that the recombination between the electrons flowing into the Ag nanoparticle and the holes left in the TiO2 valence band is significantly suppressed, particularly in the presence of CH3OH. The high activity and selectivity in the present Ag/TiO2-photocatalyzed reduction are rationalized in terms of the charge separation efficiency, the selective adsorption of the reactants on the catalyst surfaces, and the restriction of the product readsorption. 相似文献
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S. Saikan 《Applied Physics A: Materials Science & Processing》1978,16(3):235-237
J-dependence of intensity-dependent polarization change of the elliptically polarized light in atomic resonance lines is studied
both theoretically and experimentally. 相似文献
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Stimulated Raman scattering (SRS) spectra in several mixed liquids with a large optical Kerr constant are studied with nanosecond and picosecond light pulses. These spectra show a dependence of the SRS intensity on the relaxation times T2 of Raman active modes. 相似文献
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Intensity dependent polarization change and rotation of elliptically polarized light are observed and analyzed in the D1 and D2 resonance lines of sodium. The characteristics of these effects in terms of the difference between self- and cross- saturation coefficients are discussed for transitions with arbitrary values of total angular momentum J. 相似文献
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Gold nanoparticles were fabricated by reduction of highly concentrated Au(III) ions (200 mM) with casein proteins from milk. The gold nanoparticles were converted to nanoparticle-powders after washing and subsequent vacuum drying without aggregation. The nanoparticle-powders completely re-dispersed in aqueous solution, and stable colloidal gold nanoparticles were obtained. UV-vis extinction spectra and dynamic light scattering (DLS) measurements revealed that large assemblies (size, ca. 3 μm) and subaggregates (size, <0.5 μm) composed of gold nanoparticle-casein protein chain-Au(III) ion were dynamically formed and disintegrated over the course of the growth of the gold nanoparticles. Fourier transform infrared (FT-IR) spectra indicated conformational changes of casein proteins induced by the interaction of casein protein-Au(III) ion and -gold nanoparticle. Finally, rapid, one-pot, and highly concentrated synthetic procedures of gold and silver nanoparticle powders protected by casein (mean diameters below 10 nm) were successfully developed using 3-amino-1-propanol aqueous solutions as reaction media. Dense colloidal gold (40 g L(-1)) and silver (22 g L(-1)) nanoparticle aqueous solutions were obtained by re-dispersing the metal nanoparticle powders. 相似文献