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The nuclear spin conversion of CH(4) and CD(4) isolated in solid parahydrogen was investigated by high resolution Fourier transform infrared spectroscopy. From the analysis of the temporal changes of rovibrational absorption spectra, the nuclear spin conversion rates associated with the rotational relaxation from the J=1 state to the J=0 state for both species were determined at temperatures between 1 and 6 K. The conversion rate of CD(4) was found to be 2-100 times faster than that of CH(4) in this temperature range. The faster conversion in CD(4) is attributed to the quadrupole interaction of D atoms in CD(4), while the conversion in CH(4) takes place mainly through the nuclear spin-nuclear spin interaction. The conversion rates depend on crystal temperature strongly above 3.5 K for CH(4) and above 2 K for CD(4), while the rates were almost constant below these temperatures. The temperature dependence indicates that the one-phonon process is dominant at low temperatures, while two-phonon processes become important at higher temperatures as a cause of the nuclear spin conversion. 相似文献
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Otsuki J Shimizu S Fumino M 《Langmuir : the ACS journal of surfaces and colloids》2006,22(14):6056-6059
Tripod-type molecules with long alkyl chains, 1,1,1-tris(4-alkoxyphenyl)ethanes with octadecyloxy or docosyloxy chains, self-assemble into two-dimensional crystallites on drop-casting onto the surface of highly oriented pyrolytic graphite. In the two-dimensional crystalline domain, the molecules are organized in a mortise-and-tenon motif, as revealed by scanning tunneling microscopy. The time evolution of the crystallite formation has been followed by the dynamic force mode atomic force microscopy. The tripods may be used as a basis for the extension of a two-dimensional order into three-dimensional molecular architectures. 相似文献
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Akane Sato Mizuho Okada Kazuya Saito Michio Sorai 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(5):564-565
In the crystal structure of the title charge‐transfer complex, namely trans‐stilbene–2,2′‐(2,3,5,6‐tetrafluorobenzene‐1,4‐diylidene)propanedinitrile (1/1) (trans‐STB–TCNQF4), C14H12·C12F4N4, the planar STB and TCNQF4 molecules are stacked alternately. The structure is not isostructural with that of STB–TCNQ. No anomaly was found in the displacement parameters of any atoms, while the bond length of the central C=C moiety was shorter than the corresponding bond in ethylene. This suggests that the central C=C moiety of the STB molecule vibrates with a large amplitude, similar to the case in free STB and STB–TCNQ. 相似文献
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Mizuho Sugiuchi Dr. Yukatsu Shichibu Prof. Katsuaki Konishi 《Angewandte Chemie (International ed. in English)》2018,57(26):7855-7859
2,3‐bis(diphenylphosphino)butane enantiomers (chiraphos, L) used as chiral auxiliaries results in the preferential formation of an unprecedented Au24 framework with inherent chirality. The crystal structure of [Au24L6Cl4]2+ ( 1 ) has a square antiprism‐like octagold core twinned by two helicene‐like hexagold motifs, where the inherent chirality is associated with the helical arrangement. The clusters carrying (R,R)‐ and (S,S)‐ diphosphines had right‐ and left‐handed strands, respectively. Circular dichroism spectra showed peaks in the visible to near‐IR region, some of which did not coincide with absorption bands, suggesting the enantiomeric Au24 frameworks possess unique chiroptical properties. The Au24 frameworks were thermally robust, which could be attributed to the superatomic concept (18 e? system) and the steric constraint effects of the bridging ligand units. 相似文献
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Mizuho Nisizawa 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(4):701-705
The radiation protective effect of the breaking of secondary bonding in protein was examined with such amino acids as disodium inosine-5′ -monophosphate and disodium guanosine-5′ -monophosphate and vitamins such as thiamine and λ-ascorbic acid. The behavior of the viscosity change closely resembles that found with the sodium 1-glutamate as shown by a similar dependence on concentration. 相似文献