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41.
Stulz E Scott SM Ng YF Bond AD Teat SJ Darling SL Feeder N Sanders JK 《Inorganic chemistry》2003,42(20):6564-6574
The synthesis of linear multiporphyrin arrays with mono- and bisphosphine-substituted porphyrins as ligand donors and ruthenium(II) or rhodium(III) porphyrins as ligand acceptors is described. With appropriate amounts of the building blocks mixed, linear dimeric and trimeric arrays have been synthesized and analyzed by (1)H NMR and (31)P NMR spectroscopy. The Ru/Rh acceptor porphyrins can be located either at the periphery or in the center of the array. Likewise, the monophosphine porphyrins can be positioned at the periphery, thus allowing a high degree of freedom in the overall composition of the arrays. This way, both donor and acceptor porphyrins can act as chain extenders or terminators. One of the trimeric complexes with two nickel and one ruthenium porphyrin has also been analyzed by X-ray crystallography. Attempts have also been made to synthesize higher order arrays by mixing appropriate amounts of the porphyrins; however, from the NMR data it cannot be concluded if monodisperse five, seven, or nine porphyrin arrays are present or if the solutions are composed of a statistical mixture of smaller and larger arrays. 相似文献
42.
CuAl2O4, NiAl2O4, and three ternary spinels CuxNi1?xAl2O3 have been prepared, in polycrystalline form, by solid-state reaction of mixtures of CuO, NiO, and Al2O3 at 1223 K. X-Ray powder diffractometry, coupled with adequate computational methods, allowed determination of the unit-cell length, oxygen positional parameter, and cation distribution for each compound. Interdependence of these structural parameters is closely analyzed on the ternary oxide spinels. The one-electron difference between the Cu2+ and Ni2+ ions was found to be enough to render them distinguishable by X-ray powder diffraction. 相似文献
43.
44.
A systematic study of the bulk and surface geometrical and electronic properties of a series of transition-metal carbides (TMC with TM = Ti, V, Zr, Nb, Mo, Hf, Ta, and W) by first-principles methods is presented. It is shown that in these materials the chemical bonding is strongly covalent, the cohesive energies being directly related to the bonding-antibonding gap although the shift of the center of the C(2s) band related peak in the density of states with respect to diamond indicates that some metal to carbon charge transfer does also take place. The (001) face of these metal carbides exhibits a noticeable surface rumpling which grows along the series. It is shown that neglecting surface relaxation results in very large errors on the surface energy and work function. The surface formation induces a significant shift of electronic energy levels with respect to the corresponding values in the bulk. The extent and nature of the shift can be understood from simple bonding-antibonding arguments and is enhanced by the structural rippling of this surface. 相似文献
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46.
Š. Višňovský 《Czechoslovak Journal of Physics》1987,37(12):1377-1393
The paper presents the classification of the electronic empty lattice eigenvalues and the classification of the Bloch sums for the garnet structureIa3d (O
h
10
) at the symmetry points, H, P, andN of the Brillouin zone. This provides a starting point for the energy band studies of these technologically important materials.The author thanks Dr. V. Frei for useful comments. 相似文献
47.
Abachi S Akerlof C Baringer P Blockus D Brabson B Brom J Bylsma BG Chapman J Cork B DeBonte R Derrick M Errede D Gan KK Jung C Ken MT Koltick D Kooijman P Loeffler FJ Loos JS Low EH McIlwain RL Meyer DI Miller DH Musgrave B Neal H Ng CR Nitz D Ogren H Paik HW Price LE Rangan LK Repond J Rust DR Shibata EI Sugano K Thun R Tschirhart R 《Physical review letters》1987,59(22):2519-2522
48.
Abachi S Baringer P Bylsma BG DeBonte R Koltick D Loeffler FJ Low EH McIlwain RL Miller DH Ng CR Rangan LK Shibata EI Derrick M Gan KK Kooijman P Loos JS Musgrave B Price LE Repond J Sugano K Weiss JM Wood DE Blockus D Brabson B Brom J Jung C Ogren H Rust DR Akerlof C Chapman J Errede D Kesten P Meyer DI Nitz D Seidl AA Thun R Willutzky M Cork B 《Physical review letters》1986,57(16):1990-1993
49.
50.
We study quantitatively the reactions \(e^ + e^ - \to W^ + e\bar \nu _e \) ,e R ? e + and the rare decay \(Z^0 \to W^ \pm l^ \mp \mathop {\nu _e }\limits^{( - )} \) forl=e, μ and τ, as a test for anomalous γW + W ? andZ 0 W + W ? structure. If κ denotes the anomalous magnetic moment of theW-boson and ω its anomalous coupling to theZ 0, values of |ω|>2.5 and |κ|>1.5 can be ruled out at LEP and SLC rather easily. This will put constraints on composite model building. 相似文献