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31.
We have measured the nonlocal resistance of aluminum-iron spin-valve structures fabricated by e-beam lithography and shadow evaporation. The sample geometry consists of an aluminum bar with two or more ferromagnetic wires forming point contacts to the aluminum at varying distances from each other. In the normal state of aluminum, we observe a spin-valve signal which allows us to control the relative orientation of the magnetizations of the ferromagnetic contacts. In the superconducting state, at low temperatures and excitation voltages well below the gap, we observe a spin-dependent nonlocal resistance which decays on a smaller length scale than the normal-state spin-valve signal. The sign, magnitude, and decay length of this signal are consistent with predictions made for crossed Andreev reflection. 相似文献
32.
The first successful operation of an X-ray interferometer under conditions of non-planar three-beam diffraction for phase-contrast X-ray microtomography is reported. Intrinsic phase differences of the reflections used cancel from the three-dimensional phase image of the specimen. With simultaneous hkl and hkl reflections of a synchrotron radiation beam in a side-by-side geometry, the size of the usable field of view is doubled and the investigated specimen volume is increased by a factor of four. As an example, the reconstructed slice of a mouse kidney is shown in phase contrast at 71 keV. Optimized choices of three-beam reflections and matching interferometer geometries useful for applications are presented. 相似文献
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Uwe Klingebiel Stefan Schmatz Eike Gellermann Christian Drost Mathias Noltemeyer 《Monatshefte für Chemie / Chemical Monthly》2001,40(5):1105-1124
This review describes the synthesis and isomerization reactions of cyclic silylhydrazines. Topics of discussion are the ring
expansion of the three-membered Si(SiN2) to the four-membered (SiN)2 ring by lithiation of the (SiN2) ring and by thermal silyl group insertion into the N*N bond, the ring expansion of a three-membered (SiN2) to a five-membered (CSi2N2) ring by SiCH2 insertion into the Si*N bond, the formation of isomeric four- and six-membered (SiN2)2 rings, the synthesis of five- and six-membered silylhydrazine rings, and the expansion of a five-membered (N2Si2N)N ring to the isomeric six-membered (SiNN)2 ring. The mechanisms of the isomerizations are explained by quantum chemical calculations, and the results are verified by
crystal structure determinations. 相似文献
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We correlate an X-ray determination of the molecular and crystal structures of 2-tert-butylanthracene and 2-tert-butylanthraquinone reported here with the previously reported dynamical nuclear magnetic resonance determination of the motions of the tert-butyl groups and their resident methyl groups in the solid state [P.A. Beckmann, K.S. Burbank, M.M.W. Lau, J.N. Ree, T.L. Weber, Chem. Phys. 290 (2003) 241]. 相似文献
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E. Beckmann E. Bark N. Zuntz W. Lenz Berthelot Jungfleisch und A. A. Jakowkin 《Fresenius' Journal of Analytical Chemistry》1917,56(5):262-266
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