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991.
Wada E Shirahata Y Naito T Itoh M Yamaguchi M Taniyama T 《Physical review letters》2010,105(15):156601
We report on the inversion of spin-dependent photocurrent via interface localized states formed at the interface of an Fe/n-AlGaAs/GaAs quantum well heterostructure by means of an optical spin orientation technique. A careful adjustment of the excitation photon energy, which is determined by a separate analysis of electroluminescence spectra under a spin injection condition, enables us to explore the spin-dependent characteristics of photoelectron transmission from the quantum well into Fe. The bias dependence of the spin-dependent photocurrent shows clear spikelike features at the voltage which is compatible with the formation of the interface localized resonant states in the Schottky depletion layer. 相似文献
992.
We propose and demonstrate an all-optical analog-to-digital conversion system with a spatial coding method using a designed
filter. To make available codes more flexible, the design technique for a computer-generated hologram is introduced to our
spatial coding scheme. By designing the spatial coding filter appropriately, this coding scheme enables us to output various
digital signals as spatial patterns. By combining this coding method with the optical quantization method using soliton self-frequency
shifting in a fiber, the proposed system converts analog sampled signals into arbitrary digital signals. Preliminary experimental
results show that 3-bit Gray codes are successfully output as spatial patterns using the designed spatial coding filter. 相似文献
993.
Tsuda S Yokoya T Takano Y Kito H Matsushita A Yin F Itoh J Harima H Shin S 《Physical review letters》2003,91(12):127001
The superconducting-gap of MgB2 has been studied by high-resolution angle-resolved photoemission spectroscopy. The results show that superconducting gaps with values of 5.5 and 2.2 meV open on the sigma band and the pi band, respectively, but both the gaps close at the bulk transition temperature, providing a definitive experimental evidence for the two-band superconductivity with strong interband pairing interaction in MgB2. The experiments validate the role of k-dependent electron-phonon coupling as the origin of multiple-gap superconductivity as well as the high transition temperature of MgB2. 相似文献
994.
Mitsuru Nagasono Kazuhiko Mase Shin-ichiro Tanaka Tsuneo Urisu 《Surface science》1997,390(1-3):102-106
Photostimulated ion desorption at the 4a1 ← N 1s resonant transition of condensed NH3 was studied using electron emission spectroscopy and Auger-electron photoion coincidence (AEPICO) spectroscopy. The total ion yield divided by the Auger-electron yield exhibited a threshold peak at hν = 399 eV which is ascribed to the resonant transition from the N 1s to the N---H antibonding 4a1 orbital. The electron emission spectrum at the 4a1 ← N 1s resonance is decomposed into three components: a valence photoelectron emission spectrum, and normal- and resonant-Auger-electron emission spectra. We ascribe the resonant-Auger-electron emission spectrum mainly to spectator-Auger transitions on the basis of the peak assignment. A series of AEPICO spectra at the 4a1 ← N 1s resonance was also measured as a function of the Auger-electron kinetic energy. The electron kinetic energy dependence of the H+ AEPICO yield displays a shape approximately similar to that of the mixed spectrum of normal- and spectator-Auger-electron emission spectra. Based on this result the H+ desorption at the 4a1 ← N 1s resonance is concluded to originate from the spectator-Auger transitions and from the normal-Auger transitions following the delocalization of the excited electron. 相似文献
995.
Miura T Nakashima K Tada N Itoh A 《Chemical communications (Cambridge, England)》2011,47(6):1875-1877
Oxidation of alcohols in the presence of a catalytic amount of fluorous IBX and Oxone as a co-oxidant resulted in the corresponding carbonyl compounds in good to high yields. The fluorous IBX is readily recovered as insoluble fluorous IBA from the reaction mixture by simple filtration, and can be reused without significant loss of the catalytic activity. 相似文献
996.
A mesoporous silica FSM-16 was found to be a recyclable oxidizing promoter of arylmethyl bromides for the preparation the corresponding carboxylic acids, aldehydes, or ketones under photoirradiation conditions. 相似文献
997.
Wen P Itoh H Tang W Feng Q 《Langmuir : the ACS journal of surfaces and colloids》2007,23(23):11782-11790
Anatase-type TiO2 single nanocrystals with boatlike, comblike, sheetlike, leaflike, quadrate, rhombic, and wirelike particle morphologies were prepared by hydrothermal treatment of a layered titanate nanosheet colloidal solution. The formation reactions and surface properties of the TiO2 nanocrystals were investigated using XRD, TEM, TG-DTA analyses, and measurements of BET specific surface area, photocatalytic activity, and ruthenium dye (N719) adsorption. The crystal morphology can be controlled by reaction temperature, pH value of reaction solution, and exfoliating agent. The titanate nanosheets were transformed to the TiO2 nanocrystals by two types of reactions. One is an in situ topotactic structural transformation reaction, and the other is a dissolution-deposition reaction on the surface. The anatase nanocrystals formed by the in situ topotactic structural transformation reaction retain the sheetlike particle morphology of the precursor, and they preferentially expose the (010) plane of anatase structure. The crystal surface of anatase nanocrystals prepared in this study showed higher photocatalytic activity and higher ruthenium dye adsorption capacity than did the Ishihara ST-01 sample, a standard anatase nanocrystal sample. The results indicated the (010) plane of the anatase structure has high photocatalytic activity and high ruthenium dye adsorption ability. 相似文献
998.
Mitsutoshi Kimura Akiyuki Iwata Masahiro Itoh Kazuki Yamada Tsutomu Kimura Noriyuki Sugiura Masaru Ishida Shinzi Kato 《Helvetica chimica acta》2006,89(4):747-783
A series of [(thioacyl)thio]‐ and (acylseleno)antimony and [(thioacyl)thio]‐ and (acylseleno)bismuth, i.e., (RCSS)xMR and (RCOSe)xMR (M = Sb, Bi, R1 = aryl, x = 1–3), were synthesized in moderate to good yields by treating piperidinium or sodium carbodithioates and ‐selenoates with antimony and bismuth halides. Crystal structures of (4‐MeC6H4CSS)2Sb(4‐MeC6H4) ( 9b′ ), (4‐MeOC6H4COSe)2Sb(4‐MeC6H4) ( 12c′ ), (4‐MeOC6H4COS)2Bi(4‐MeC6H4) ( 15c′ ), and (4‐MeOC6H4CSS)2BiPh ( 18c ) along with (4‐MeC6H4COS)2SbPh ( 6b ) and (4‐MeC6H4COS)3Sb ( 7b ) were determined (Figs. 1 and 2). These compounds have a distorted square pyramidal structure, where the aryl or carbothioato (= acylthio) ligand at the central Sb‐ or Bi‐atom is perpendicular to the plane that includes the two carbodithioato (= (thioacyl)thio), carboselenato (= acylseleno), or carbothioato ligand and exist as an enantiomorph pair. Despite the large atomic radii, the C?S ??? Sb distances in (RCSS)2MR1 (M = As, Sb, Bi; R1 = aryl) and the C?O ??? Sb distances in (RCOS)xMR (M = As, Sb, Bi; x = 2, 3) are comparable to or shorter than those of the corresponding arsenic derivatives (Tables 2 and 3). A molecular‐orbital calculation performed on the model compounds (MeC(E)E1)3?xMMex (M = As, Sb, Bi; E = O, S; E1 = S, Se; x = 1, 2) at the RHF/LANL2DZ level supported this shortening of C?E ??? Sb distances (Table 4). Natural‐bond‐orbital (NBO) analyses of the model compounds also revealed that two types of orbital interactions nS → σ and nS → σ play a role in the (thioacyl)thio derivatives (MeCSS)3?xMMex (x = 1, 2) (Table 5). In the acylthio‐MeCOSMMe2 (M = As, Sb, Bi), nO → σ contributes predominantly to the orbital interactions, but in MeCOSeSbMe2, none of nO → σ and nO → σ contributes to the orbital interactions. The nS → σ and nS → σ orbital interactions in the (thioacyl)thio derivatives are greater than those of nO → σ and nO → σ in the acylthio and acylseleno derivatives (MeCOE)3?xMMex (E = S, Se; M = As, Sb, Bi; x = 1, 2). ?The reactions of RCOSeSbPh2 (R = 4‐MeC6H4) with piperidine led to the formation of piperidinium diphenylselenoxoantimonate(1?) (= piperidinium diphenylstibinoselenoite) (H2NC5H10)+Ph2SbSe?, along with the corresponding N‐acylpiperidine (Table 6). Similar reactions of the bis‐derivatives (RCOSe)2SbR1 (R, R1 = 4‐MeC6H4) with piperidine gave the novel di(piperidinium) phenyldiselenoxoantimonate(2?) (= di(piperidinium) phenylstibonodiselenoite), [(H2NC5H10)+]2(PhSbSe2)2?, in which the negative charges are delocalized on the SbSe2 moiety (Table 6). Treatment of RCOSeSbR (R, R1 = 4‐MeC6H4) with N‐halosuccinimides indicated the formation of Se‐(halocyclohexyl) arenecarboselenoates (Table 8). Pyrolysis of bis(acylseleno)arylbismuth at 150° gave Se‐aryl carboselenoates in moderate to good yields (Table 9). 相似文献
999.
A novel system using a potassium aluminosilicate electrolyte under applied potential that is able to split H2O (or OHˉ) into H2 and 1/2O2 (or O2
2-) with higher yields than the value deduced from Faraday"s law is presented. There were three steps by which H2 and O2 were generated stoichiometrically, and it was predicted that the high yields were due to the occurrence of chemically endothermic
reactions: dehydration of the catalytic cell at a temperature below 100°C (step I), disproportionation of KOH (2KOH→H2+K2O2) at a temperature around 200°C (step II), and disproportionation of K2O (2K2O→K2+K2O2) at a temperature above 500°C (step III). So-called Nemca might be caused in the course of step III, since the rate of H2 was ca 102 times larger than the value deduced from Faraday"s law.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
1000.
Reflection spectroscopy of deionized suspensions of the thermo-sensitive gels of poly (N-isopropylacrylamide) with various degrees of cross-linking were made in the sedimentation equilibrium at 20 °C. Rigidity of the crystals increased as sphere concentration increased and increased slightly as the degree of the cross-linking of the gel spheres increased. The fluctuation parameters of the gel crystals were between 0.05 and 0.07 and slightly larger than those of typical hard-sphere systems. These experimental results emphasize that the gel crystals are soft compared with those of typical hard-sphere systems and role of the extended electrical double layers for the crystallization of gel spheres is important but weak compared with that of hard colloidal spheres. 相似文献