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排序方式: 共有369条查询结果,搜索用时 31 毫秒
41.
U. Wahl J. G. Correia E. Rita E. Alves J. C. Soares B. De Vries V. Matias A. Vantomme 《Hyperfine Interactions》2004,159(1-4):363-372
We present results of recent emission channeling experiments on the lattice location of implanted Fe and rare earths in wurtzite
GaN and ZnO. In both cases the majority of implanted atoms are found on substitutional cation sites. The root mean square
displacements from the ideal substitutional Ga and Zn sites are given and the stability of the Fe and rare earth lattice location
against thermal annealing is discussed. 相似文献
42.
Charlotte Wahl 《Proceedings of the American Mathematical Society》2007,135(12):4063-4073
A general integral formula for the spectral flow of a path of unbounded selfadjoint Fredholm operators subject to certain summability conditions is derived from the interpretation of the spectral flow as a winding number.
43.
M. Wahl D. Koch W. Berthold A. Wucher 《Fresenius' Journal of Analytical Chemistry》1995,353(3-4):354-359
Using a reflectron time-of-flight mass spectrometer, the ionization process in non-resonant Laser postionization Secondary Neutral Mass Spectrometry (SNMS) has been investigated. In particular, the postionization efficiencies (PIE) achieved by multi photon and single photon absorption have been compared by ionizing ten elements sputtered from a NIST standard reference material by excimer laser radiation of 248 nm, 193 nm and 157 nm. Only in the case of single photon ionization (SPI) the measured laser intensity dependence of the PIE can be understood quantitatively in terms of corresponding theory. From the results, absolute values of the SPI cross sections have been evaluated for atoms of nine elements, which show a total variation over about two orders of magnitude. Furthermore, even in the regime of high laser intensity, where the ionization of all atoms is completely saturated, different elements have been detected with relative sensitivity factors which scatter over about one order of magnitude. This has been attributed to element dependent variations of the effective ionization volume which are caused by the different kinetic energy and angular distributions of different sputtered atoms. 相似文献
44.
Let Ω be a bounded domain in ?3 with a connected Lipschitz boundary ?Ω. Consider the Navier-Stokes system. 相似文献
45.
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
46.
47.
J.G.H. de Groot T. Hansl M. Holder J. Knobloch J. May P. Palazzi A. Para F. Ranjard A. Savoy-Navarro D. Schlatter J. Steinberger W. von Rüden H. Wahl F. Eisele K. Kleinknecht H. Lierl H.J. Willutzki F. Dydak F.L. Navarria 《Physics letters. [Part B]》1979,86(1):103-107
290 events of the type νFe→μ?μ?X and 53 events from the reaction and muon momenta pμ>6.5GeV/c have been observed in the CDHS detector. After subtracting the background from charged-current processes with one π or K meson of the hadronic shower decaying into , we obtain for neutrinos a rate of prompt like- sign dimuon production of (3.4±1.8)×10?5 relative to the rate of charged-current events with the same cuts, or (4.1 ± 2.2)% relative to the prompt μ?μ+ rate, and for antineutrinos the corresponding relative rates (4.3±2.3)×10?5 and (4.2 ± 2.3)%. A possible explanation for the events is charm pair production at a level of 10?3 relative to all charged-current reactions. 相似文献
48.
49.
J. Wahl 《Solid State Communications》1979,29(6):485-490
Lithium ionic conductivity of Li3N single crystals is reported for temperatures from 120 K to 350 K. The intrinsic ionic conductivity is rather small (< 10?6 Ω?1 cm?1 at 300 K) and shows no strong anisotropy. The activation energy is near 0,6 eV. It is shown that hydrogen is the critical impurity in the crystals grown and studied at this laboratory. The relative impurity concentration is determined from infrared transmission measurements near 3130 cm?1. An estimate for absolute values is obtained from dielectric studies. Increases in ionic conductivity with hydrogen doping by a factor 5000 are reported for E⊥c but no significant effects are found for E6c. The proposed defect is an impurity-vacancy complex consisting of an NH?? and a lithium vacancy. 相似文献
50.
Global classical solutions of nonlinear wave equations 总被引:2,自引:0,他引:2