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1.
New Ternary Clathrate Compounds in the Systems Barium–Indium/Zinc/Cadmium–Germanium: Zintl Compounds with Phase Width? By systematic investigations in the systems barium–indium/zinc/cadmium–germanium we found a couple of new electrovalent ternary compounds with A8X46 clathrate (I) type structures. They crystallize cubically in space-group Pm3n. For Ba8In16Ge30 (a = 1 075.8 pm), Ba8Zn8Ge38 (a = 1 082.0 pm) and Ba8Cd8Ge38 (a = 1 096.0 pm) the structures were verified by X-ray single crystal diffraction data. According to valence and bounding distances the new clathrates should be Zintl compounds. Measurements of the temperature dependence of the electrical resistivity proved, that they are indeed semiconductors. A part of the 2B/3B metal atoms can be substituted by germanium. Charge balance will be retained by creation of vacancies in the A8X46 type structures. By phase analysis the limits of the composition range were determined as Ba8In4Ge9[]3Ge30 (a = 1 084.9 pm), Ba8Zn4Ge10[]2Ge30 (a = 1 073.6 pm) and Ba8Cd4Ge10[]2Ge30 (a = 1 082.0 pm). 相似文献
2.
M. Renaud J. Le Bris M. Erman D. Schmitz M. Heyen H. Jürgensen I. Grant F. Schulte C. Steinberger 《Optical and Quantum Electronics》1991,23(3):391-404
Ga
x
In1–x
As
y
P1–y
alloys lattice matched to InP substrates are currently used to fabricate optoelectronic and integrated optics devices. To achieve devices with high performances and high fabrication yield, the uniformity and reproducibility of the Ga
x
In1–x
As
y
P1–y
epitaxial layers (composition, thickness, doping, etc.) have become key parameters. These problems have been addressed in the frame of ESPRIT project 2518 and are presented in this paper. Several aspects have been considered starting from the optimization of InP substrates, the MOVPE growth of uniform GalnAsP layers, the material characterization to the validation of material uniformity on passive optical waveguides. Both scanning photoluminescence analysis and waveguide losses measurements performed on 2 inch wafers with a high lateral resolution have shown that high quality uniform GalnAsP layers can be obtained reproducibly on 2 InP substrates using a commercially available LP-MOCVD growth process. In particular, more than 60% of 36 mm long, 3m wide and 100m spaced rib waveguides exhibit losses below 0.8dBcm–1. 相似文献
3.
H. Abramowicz F. Dydak J. G. H. de Groot J. Knobloch J. May P. Palazzi F. Ranjard W. D. Schlatter J. Steinberger H. Taureg W. von Rüden H. Wahl J. Wotschack P. Buchholz F. Eisele H. P. Klasen K. Kleinknecht B. Pszola B. Renk H. J. Willutzki T. Flottmann C. Geweniger J. Krolikowski K. Tittel C. Guyot J. P. Merlo A. Para B. Peyaud J. Rander J. Rothberg J. P. Schuller R. Turlay J. T. He T. Z. Ruan W. M. Wu 《Zeitschrift fur Physik C Particles and Fields》1982,12(3):225-227
Right handed weak quark currents coupled to the usual left handed weak lepton current would be seen in inclusive antineutrino scattering on nuclei as a contribution at largey with the quark (not antiquark) structure function. We do not see such a term, and can therefore put an upper limit on the relative strengths of such right handed currents: \(\varrho ^2 = \frac{{\sigma _R }}{{\sigma _L }}< 0.009\) , 90% confidence. This measurement puts limits on the mixing angle of left-right symmetric models. In distinction to similar limits derived from muon decay or β decay, our limits are also valid if the right handed neutrino is heavy. 相似文献
4.
On Organophosphorus Compounds. XV. Preparation and Reactions of Trimethylsilyl Esters of Phosphinic Acids Trimethylsilylesters of Phosphinic acids R2P(X)YSi(CH3)3 (R ? CH3, C2H5, C3H7, t?C4H9, C6H5; X, Y ? O, S) were prepared by 7 different methods as in some cases easily hydrolysable but thermally remarkably stable compounds. The properties and some reactions of these substances are reported, their structures confirmed by IR? as well as 1H- and 31P-NMR-spectroscopy. Dimethylsilylen-bis(phosphinic acid esters) were obtained according to \documentclass{article}\pagestyle{empty}\begin{document}$ 2{\rm R}_{2} {\rm P(\rm X)\rm ONH}_{4} + {\rm R}_{\rm 2} {\rm SiCl}_{2} \to 2{\rm E NH}_{4} {\rm Cl + R}_{2} {\rm P(X) - O - SiR}_{2} - {\rm O - P(X)R}_{2} ({\rm R = CH}_{3};{\rm X = O,S}) $\end{document}. 相似文献
5.
Manfred Meisel Hans-Uwe Steinberger Burkhard Ziemer Nguyen Huu Thong 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):291-293
Abstract A Guide to Organophosphorus Chemistry, by Louis D. Quin, an internationally recognized authority, published by John Wiley and Sons (http://www.wiley.com/chemistry) ISBN 0-471-31824-8, $94.95, 394pp. Aminophosphonic and Aminophosphinic Acids: Chemistry and Biological Activity. Editors: Valery P. Kukhar (Ukrainian Academy of Sciences) and Harry R Hudson (University of North London). Published by John Wiley and Sons Ltd., Chichester, UK, on 31 March, 2000. ISBN 0 471-89149-5, 175.00 Pounds sterling, 634 pages. Phosphorus Ylides. Chemistry and Application in Organic Synthesis, by Oleg I. Kolodiazhnyi. Published by Wiley-VCH, 1999, ISBN 3-527-29531-3, 220SF, 555 pages. 相似文献
6.
C. Geweniger S. Gjesdal G. Presser P. Steffen J. Steinberger F. Vanucci H. Wahl F. Eisele K. Kleinknecht G. Zech V. Lüth 《Physics letters. [Part B]》1975,57(2):193-196
A search for the decay Ξ0→pπ? has been performed in a neutral hyperon beam derived from the 24 GeV/c external proton beam at CERN. The experiment gives as a 90% confidence upper limit for the branching ratio . 相似文献
7.
Photoemission yield spectra of solid argon using synchrotron radiation for excitation in the photon energy range 11.7–16 eV show peaks closely following the known excitonic transitions, further peaks at 11.96 and 13.1 eV and also give an indication for band-gap photoconductivity. 相似文献
8.
A new method for computing the topological entropy of a piecewise monotonic transformation on the interval is presented. It uses a transition matrix associated with the transformation. For this matrix we give a spectral theorem. This can be used for an estimation of the accuracy of the algorithm. 相似文献
9.
S. Gjesdal G. Presser P. Steffen J. Steinberger F. Vannucci H. Wahl H. Filthuth K. Kleinknecht V. Lüth G. Zech 《Physics letters. [Part B]》1973,44(2):217-220
A search for the decay KS → 2μ has given negative results. The 90% confidence upper limit for the branching ratio of 3.1 × 10?7 excludes the models of Christ and Lee, and of Dass and Wolfenstein, designed to explain the KL → 2μ problem. 相似文献
10.
Mark Steinberger 《Inventiones Mathematicae》1988,91(1):61-104
Partially supported by the NSF and by the Graduate School of Northern Illinois University 相似文献