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Uwe Bhme Ines C. Foehn 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(11):o613-o616
TBPY‐5‐34‐(Butane‐1,4‐diyl)(2‐{[1‐(2‐oxidophenyl)ethylidene‐κO]amino‐κN}ethanolato‐κO)silicon, C14H19NO2Si, crystallizes in two modifications. The monoclinic form, (IIm), was obtained by crystallization over a period of 2 d at room temperature; the orthorhombic form, (IIo), crystallized overnight at 248 K. The main difference between the two molecular structures involves the angles in the equatorial plane of the trigonal bipyramid around silicon. Form (IIm) has an O—Si—O angle of ca 121° and O—Si—C angles of ca 121 and 116°. In form (IIo), the corresponding angles are ∼123, 124 and 111°. There are also significant differences in the packing: (IIm) shows π stacking, whereas (IIo) does not. 相似文献
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S. Mathias M. Wessendorf S. Passlack M. Aeschlimann M. Bauer 《Applied Physics A: Materials Science & Processing》2006,82(3):439-445
Epitaxial ultra-thin Ag films grown on Cu(111) have been investigated by angle-resolved photoemission spectroscopy. The thickness
dependence of the binding energy for the Shockley surface state at 300 K could be determined accurately in films up to 5 ML
thick. Furthermore, we observe drastic changes in the film morphology after annealing to 450 K. Spectral modifications in
the shape of the quantum-well states (QWS), characteristic for these ultra-thin silver films, prove that the surface morphology
is homogeneous. The photoemission spectra also indicate that the silver film bifurcates to form a film exhibiting two distinct
film thicknesses. For all levels of silver coverage, we identify surface regions that are 2 ML thick, while the thickness
of the remaining surface depends on the amount of deposited silver. The almost purely Lorentzian line-shape of the spectral
features corresponding to the two different surface regions show that both surface areas are atomically flat.
PACS 68.55.Jk; 73.20.At; 73.21.Fg; 79.60.Dp 相似文献
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The hydrogen-deuterium exchange of H-2 in 4-pyrimidone, a number of 1- and 3-alkyl-4-pyrimidones and several of their thione analogs in deuterium oxide at moderate temperatures is reported. This reaction is apparently not susceptible to acid or base catalysis. Cations of the 4-pyrimidones were found not to exchange H-2 at all in acid media. Catalytic amounts of bases do not alter the exchange rates whereas more concentrated alkali decompose the pyrimidone. However, 1,4(3,4)-dihydro-1,3-dimethyl-4-oxopyrimidinium iodide (and its 6-methyl analog) exchange H-2 quite rapidly in neutral deuterium oxide, almost instantly when triethylamine is added as a catalyst, and very slowly in dilute solutions of deuterium chloride in deuterium oxide. Mechanisms are proposed to account for these phenomena. 相似文献
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I. Bauer 《Fresenius' Journal of Analytical Chemistry》1967,231(6):464
Ohne Zusammenfassung 相似文献