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H. Barfuß G. Böhnlein H. Hohenstein W. Kreische H. Niedrig H. Appel R. Heidinger J. Raudies G. Then W. -G. Thies 《Zeitschrift für Physik B Condensed Matter》1982,47(2):99-102
The time differential perturbed angular correlation technique was applied to study the electric field gradient in the semiconductor CdSe and the insulator HfO2 at different temperatures. Whereas the semiconductor CdSe shows an increasing quadrupole coupling constant with increasing temperature, the insulator HfO2 exhibits no temperature dependence of the electric field gradient over the whole temperature range investigated. 相似文献
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A recent study of substituted face-to-face benzene dimers by Lewis and co-workers [J. Am. Chem. Soc. 2011, 133, 3854-3862] indicated a surprising enhancement of electrostatic interactions for both electron-withdrawing and electron-donating substituents. Here we demonstrate that charge penetration (an attractive electrostatic interaction arising from the overlap of the electron densities on the two monomers) is the cause of this counterintuitive effect. These charge penetration effects are significant at typical π-π interaction distances, and they are not easily described by multipole models. A simple measure of a substituent's electron-donating or electron-withdrawing character, such as the Hammett parameter σ(m), is unlikely to capture subtle charge penetration effects. Indeed, correlation of the relative total energies or relative electrostatic energies with ∑σ(m) breaks down for multiply substituted face-to-face benzene dimers. 相似文献
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H. Barfuß G. Böhnlein H. Hohenstein W. Kreische H. Niedrig A. Reimer 《Zeitschrift für Physik B Condensed Matter》1982,45(3):193-195
Using the TDPAC-method with the proble nucleus111Cd the electric quadrupole interaction (QI) in the trigonal semiconductor Te has been investigated in the temperature range 77 KT655 K. In contrast to most metals the quadrupole frequencyv
Q increases with increasing temperature. This is a consequence of the fact that in metals the charge carrier density is temperature independent, whereas in semiconductors it strongly increases with temperature. A comparison between the temperature variation of the quadrupole coupling constantv
Q and that of the charge carrier density leads to the conclusion that the QI in Te is governed by changes in the free electron density. 相似文献
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Hohenstein C Kadzimirsz D Ludwig R Kornath A 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(3):925-929
[Me4N]+[SO2F3]?, the first example of a [SO2F3]? salt, has been prepared from Me4NF and SO2F2. The colorless, microcrystalline solid was characterized by its infrared and Raman spectra. The trigonal bipyramidal structure of C2v symmetry of the [SO2F3]? anion is predicted by ab initio calculations. Two oxygen atoms with d(SO)=143.2 pm and one fluorine atom with d(SF)=157.9 pm occupy the equatorial plane. The two fluorine atoms in the axial position with d(SF)=168.5 pm are repulsed by the two oxygen atoms forming a bent axis with ?(FaxSFax)=165.2°. 相似文献
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E. Tournié O. Brandt K. H. Ploog M. Hohenstein 《Applied Physics A: Materials Science & Processing》1993,56(1):91-94
We show that surface stoichiometry and growth mode are intimately related for heteroepitaxy of InAs on GaO0.47In0.53As. Under As-stable conditions during molecular beam epitaxy, the high strain of the InAs film induces a morphological phase-transition from layer-by-layer to island nucleation. In contrast, under In-stable conditions without direct As4 flux, islanding is inhibited. The In-stabilized surface imposes limitations to the migration of both As and In adatoms and forces layer-by-layer nucleation, thus acting as a virtual surfactant. 相似文献
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