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154.
One-dimensional nanostructures of metals: large-scale synthesis and some potential applications 总被引:2,自引:0,他引:2
We review recent developments in our group regarding the solution-phase synthesis of one-dimensional nanostructures of metals. The synthetic approaches include solution-liquid-solid growth for nanowires of low-melting-point metals such as Pb; seed-directed growth for Ag nanowires, nanobeams, and nanobelts; kinetically controlled growth for Pt nanorods, nanowires, and multipods; and galvanic replacement for nanotubes of Au, Pt, and Pd. Both characterization and mechanistic studies are presented for each nanostructure. Finally, we highlight the electrical and plasmonic properties of these metal nanostructures and discuss their potential applications in nanoscale devices. 相似文献
155.
John B. Wiley Shiou-Mei Huang Shinho Cho Franois Diederich Robert L. Whetten Kroly Holczer Richard B. Kaner 《Macromolecular Symposia》1992,59(1):389-397
Shielding diamagnetism and X-ray powder diffraction were used to characterize alkali-metal fullerides of sodium, potassium, rubidium, and cesium. The superconducting phase in both the potassium and rubidium systems has the composition A3C60 and a face centered cubic structure with alkali metal filling all octahedral and tetrahedral sites of close packed C60, layers. High pressure magnetic susceptibility measurements on K3C60 showed a negative pressure dependence on the superconducting transition temperature of −0.78 K/kbar. No evidence for superconductivity was observed in either the sodium or cesium systems, even though Na3C60 appears isostructural with K3C60 and Rb3C60. 相似文献
156.
Indium selenide thin films are important due to their applications in non-volatile memory and solar cells. In this work, we present an initial study of a new application of deposition-site selective laser back ablation (LBA) for making thin films of In2Se3. Invacuo annealing and subsequent characterization of the films by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) indicate that control of substrate temperature during deposition and post-deposition annealing temperature is critical in determining the phase and composition of the films. The initial laser fluence and target film thickness determine the amount of material deposited onto the substrate. 相似文献
157.
[reaction: see text] A new chiral aziridino alcohol ligand for zinc(II)-catalyzed azomethine ylide cycloadditions is described. In the presence of this catalyst, N-arylidene glycine methyl esters react with a variety of dipolarophiles to give substituted pyrrolidines in very good to excellent chemical yields and up to 95% ee. The absolute sense of asymmetric induction appears to be dipolarophile-dependent. 相似文献
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Theodore E. Wiley Brenden C. Arruda Nicholas A. Miller Michael Lenard Roseanne J. Sension 《中国化学快报》2015,26(4):439-443
Cyanocobalamin (CNCbl) is a paradigm system for the study of excited electronic states and biological cofactors including the B12 vitamers. The photophysics of CNCbl has been thoroughly investigated using both ultrafast spectroscopy and time dependent density functional theory (TD-DFT). Herewe review the spectroscopic and theoretical investigations of CNCbl with emphasis on the nature of S1, the lowest excited electronic state, and extend the spectroscopic measurements to include the ultraviolet region of the spectrum. Ultrafast transient absorption measurements in the visible αβ band region and in the midinfrared led to assignment of the S1 state to a ligand-to-metal charge transfer (LMCT) with lengthened axial bonds and a ~3 kcal/mol barrier for internal conversion to the ground state. The present measurements encompassing the γ band region of the spectrum provide further support for the assignment of the S1 state. The experiments are in good agreement with the results of TD-DFT calculations which confirm the expected lengthening of the axial bonds in S1 and account for the observed barrier for internal conversion back to the ground state. 相似文献
160.
Richard H. Wiley 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(10):1183-1190
Oligomers of 2 to 9 units having a diazinediylethene-1, 2-diol repeating unit have been prepared by a cyanide ion-catalyzed self-condensation of pyridazine-3, 6-, pyrazine-2, 5-, or pyrimidine-4, 6-dialdehyde. These are the first known representatives of a class of conjugated polymeric enediol materials derivable specifically from these three structurally related diazine dialdehydes. The oligomers, isolated as their potassium salts, are soluble in acid and base with an isoelectric point at pH 6.5. In base, they give dark red-brown solutions whose color, attributable to their semidione ion radical form, is rapidly discharged by oxygen (air) or by the addition of ferric ion, which gives an immediate precipitation of the black chelate. Of several possible methods evaluated for the preparation of the free dialdehydes, only that involving ozonization of the distyryldiazines was found to be of preparative value. 相似文献