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171.
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The low temperature (125K) X-ray crystal structures of (TMTSF)2X, X=C104-, PF6-, and AsF6- reveal decreases in the intermolecular interand intrastack Se-Se contact distances upon cooling (298K to 125K) which are highly anisotropic and different from one salt to another. The changes in the interstack distances, which are normal to the stacking direction, are approximately twice those involving intrastack Se-Se interactions. These observations establish that the anisotropic structural changes which accompany decreased temperature are common to numerous (TMTSF)2X radical cation conducting salts. 相似文献
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A convenient synthesis of arachno-6,9-C2B8H14, based on the reduction of nido-5,6-C2B8H12 with sodium tetrahydroborate, is reported. Electrophilic halogenation of the former carborane produced a series of 1-X-6,9-C2B8H13 (X = Cl, Br and I) derivatives whose constitution was established on the basis of their 1H and 11B NMR spectra. 相似文献
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S.?Kallush B.?Segev R.?C?téEmail author 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2005,35(1):3-14
We explore how atoms and polar molecules can be manipulated using
evanescent-wave mirrors (EWM). We review the simpler case
of ultracold atoms incident on EWM, and show that quantum effects
such as tunneling, above barrier reflection, and Casimir retardation
corrections, can be probed. We show that it is possible to
enhance significantly quantum effects by engineering
sharp features in the effective atom-EWM potential.
We illustrate the concept with a bichromatic EWM created
by using red and blue detuned lasers. Finally, we extend the
treatment to ultracold diatomic polar molecules. Quantum
reflection and molecular state selection are
demonstrated under attainable physical conditions. By facilitating the
manipulation and trapping of ultracold molecules, such molecular
mirrors could have several applications, e.g., as devices to filter
and select state for ultracold chemistry, or to manipulate states for
quantum information processing. 相似文献
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17O solid state NMR of organic materials is developing rapidly. This article provides a snapshot of the current state of development of this field. The NMR techniques and enrichment protocols that are driving this progress are outlined. The 17O parameters derived from solid-state NMR experiments are summarized and the structural sensitivity of the approach to effects such as hydrogen bonding highlighted. The prospects and challenges for 17O solid-state NMR of biomolecules are discussed. 相似文献
180.
Supported ionic liquids: ordered mesoporous silicas containing covalently linked ionic species 总被引:1,自引:0,他引:1
Ordered mesoporous silicas with hexagonal or lamellar architectures incorporating covalently bound ionic species were synthesized via a template directed hydrolysis-polycondensation of tetraethoxysilane (TEOS) with triethoxysilylated imidazole [(EtO)(3)Si(CH(2))(3)-Im] or alkylimidazolium halides [(EtO)(3)Si(CH(2))(3)-Im(+)-R Hal(-)]. 相似文献