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11.
Palladium-catalyzed asymmetric allylic alkylation of 1,3-diphenyl-2-propenyl acetate (4) with a dimethyl malonate-BSA-LiOAc system has been successfully carried out in the presence of chiral phosphine-hydrazone ligands such as 3a in good yields with good enantioselectivities (up to 84% ee). 相似文献
12.
Low-temperature growth of ZnO epitaxial films by metal organic chemical vapor deposition 总被引:3,自引:0,他引:3
B.P.?ZhangEmail author N.T.?Binh K.?Wakatsuki N.?Usami Y.?Segawa 《Applied Physics A: Materials Science & Processing》2004,78(1):25-28
ZnO films were grown on Al2O3 (0001) substrates by metal organic chemical vapor deposition at temperatures of Tg=150300 °C. Epitaxial growth was obtained for Tg200 °C. The in-plane orientation of the ZnO unit cells was found to change from a no-twist one with respect to that of the substrate at Tg=200 °C to a 30°-twist one at Tg=300 °C. Absorption and photoluminescence were observed from the film grown at 150 °C, although there was no evidence of epitaxial growth. Films grown at Tg200 °C exhibited smoother surfaces. Moreover, all the films grown at Tg=150300 °C revealed acceptor-related emission peaks, indicating the incorporation of acceptors into the films. PACS 81.15.Gh; 78.55.Et; 78.66.Hf 相似文献
13.
B.P.?ZhangEmail author N.T.?Binh K.?Wakatsuki N.?Usami Y.?Segawa 《Applied Physics A: Materials Science & Processing》2004,79(7):1711-1714
Single-crystalline ZnO tubes were grown on sapphire(0001) substrates by metalorganic chemical vapor deposition at 400 °C. The growth temperature was much lower than that (900–1100 °C) used in previous reports. The tubes were grown along the substrate normal and were characterized by hexagon-shaped cross sections. All of the tubes possessed the same epitaxial relationships with respect to the substrate. Growth pressure was found to play an important role in the formation of ZnO tubes. PACS 61.46.+w; 78.67.-n; 81.15.Gh 相似文献
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Sasaki S Kriener M Segawa K Yada K Tanaka Y Sato M Ando Y 《Physical review letters》2011,107(21):217001
A topological superconductor (TSC) is characterized by the topologically protected gapless surface state that is essentially an Andreev bound state consisting of Majorana fermions. While a TSC has not yet been discovered, the doped topological insulator Cu(x)Bi(2)Se(3), which superconducts below ~3 K, has been predicted to possess a topological superconducting state. We report that the point-contact spectra on the cleaved surface of superconducting Cu(x)Bi(2)Se(3) present a zero-bias conductance peak (ZBCP) which signifies unconventional superconductivity. Theoretical considerations of all possible superconducting states help us conclude that this ZBCP is due to Majorana fermions and gives evidence for a topological superconductivity in Cu(x)Bi(2)Se(3). In addition, we found an unusual pseudogap that develops below ~20 K and coexists with the topological superconducting state. 相似文献
17.
In this paper, we theoretically and numerically investigate a new type of analytically solvable laser-driven systems inspired by electron-injection dynamics in dye-sensitized solar cells. The simple analytical expressions are found to be useful for understanding the difference between dye excitation and direct photo-injection occurring between dye molecule and semiconductor nanoparticles. More importantly, we propose a method for discriminating experimentally dye excitation and direct photo-injection using time-dependent fluorescence. We have found that dye excitation shows no significant quantum beat, whereas the direct photo-injection shows a significant quantum beat. 相似文献
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H. Segawa S. Yamaguchi Y. Yamazaki T. Yano S. Shibata H. Misawa 《Applied Physics A: Materials Science & Processing》2006,83(3):447-451
Two-dimensional (2D) pillar arrays with submicrometer to micrometer repetitions have been fabricated from hybrid organic–inorganic
material by mask lithography or multi-beam interference lithography. The type of array structure depends on structural parameters
such as the pillar height, diameter and distance between neighboring pillars. Two kinds of periodic arrays, 2D arrays and
‘top-gathering’ arrays, can be obtained by controlling the structural parameters. In the top-gathering arrays, the pillars
are gathered at the top by means of self-organization, and ‘top-gathering’ units composed of four pillars can be formed.
PACS 68.35.Gy; 81.20.Fw; 82.50.-m 相似文献