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1.
A. S. Aynacioglu G. von Oppen R. Müller 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1987,6(2):155-162
We investigated the excitation of the λ(1s3d 3 D?1s2p 3 P)=588 nm line of atomic helium by proton and deuteron impact for projectile energies 10 keV≦E p≦25 keV. In apparent contradiction to Wigner's spin conservation rule, the emission cross section does not vanish. By measuring the intensity of the impact radiation as a function of homogeneous magnetic and electric fields applied to the collision volume, it has been shown thatp- andd-impact excitation of the 1s3d 3 D level of HeI proceeds via 1snl states withl≧3, which populate the 33 D states by cascade decays. The well-known strong singlet-triplet mixing of these 1snl states enables a population of triplet states in accord with Wigner's rule. Accordingly, we determine the excitation cross section of the 1s4f multiplet from the measured emission cross section of the 588 nm line. The field-dependent signals give evidence that predominantly substates with |m L|≦1 are excited. 相似文献
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A. S. Aynacioglu A. -H. Meißner F. Walachowicz G. v. Oppen 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1991,18(1):85-91
The magnetic depolarization of the impact radiation at λ(41 D?21 P)=492 nm and λ(31 D?21 P) = 668 nm as well as the splitting of the magnetic depolarisation signals in electric fields were investigated for 10–25 keV H 2 + (D 2 + )-He collisions (only 492 nm line) and for 5-22.5 keV He-He collisions (both lines). The results are compared with analogous measurements for He+- He and Ne+ - He collisions and the dynamics of the excitation process are qualitatively discussed. In particular, we emphasize the importance of inertia for the evolution of the electron cloud during the final phase of the collision process. 相似文献
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C. W. Griffin Margaretha v. Saaf F. C. Oppen 《Analytical and bioanalytical chemistry》1938,112(11-12):418-419
6.
We study the transport properties of pinned striped quantum Hall phases. We show that, under quite general assumptions, the macroscopic conductivity tensor satisfies a semicircle law. In particular, this result is valid for both smectic and nematic stripe phases, independent of the presence of topological and orientational defects such as dislocations and grain boundaries. As a special case, our results explain the experimental validity of a product rule for the dissipative part of the resistivity tensor, which was previously derived by MacDonald and Fisher (cond-mat/9907278) for a perfect stripe structure. 相似文献
7.
The mutual influence of two layers with strongly localized electrons is exercised though the random Coulomb shifts of site energies in one layer caused by electron hops in the other layer. We trace how these shifts give rise to a voltage drop in the passive layer, when a current is passed through the active layer. We find that the microscopic origin of drag lies in the time correlations of the occupation numbers of the sites involved in a hop. These correlations are neglected within the conventional Miller-Abrahams scheme for calculating the hopping resistance. 相似文献
8.
R. Jung S. Gerlach R. Schumann G. von Oppen U. Eichmann 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(3):415-419
We report on the first successful loading of a magneto-optical trap (MOT) with metastable He atoms from a Stark-slower. Thereby,
deceleration of the atoms relies on laser-atom interaction in an inhomogeneous electric field. We show that the results obtained
are comparable with early results from other groups achieved with a Zeeman slower. The Stark slower, which is able to fully
control the final velocity of the atomic He beam, is the first step in achieving complete spin independent kinematic control
based solely on electric fields.
Received 2 October 2002 / Received in final form 20 January 2003 Published online 29 April 2003
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ID="a"e-mail: eichmann@mbi-berlin.de 相似文献
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Elif Orhan Didem Omay Yküsel Gvüenilir 《Applied biochemistry and biotechnology》2005,121(1-3):183-194
The aim of this experimental study was to isolate and partially purify protease enzyme from Bacillus cereus and Bacillus subtilis. Protease enzyme is obtained by inducing spore genesis of bacteria from Bacillus species in suitable nutrient plates. The partial purification was realized by applying, respectively, ammonium sulfate precipitation, dialysis, and DEAE-cellulose ion-exchange chromatography to the supernatant that was produced later. Optimum pH, optimum temperature, pH stability, and temperature stability were determined, as well as the effects of pH, temperature, substrate concentration, reaction time, and inhibitors and activators on enzyme activity. In addition, the molecular mass of the obtained enzyme was investigated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The specific activity of partially purified enzyme from B. subtilis was determined to be 84 U/mg. The final enzyme preparation was eight-fold more pure than the crude homogenate. The molecular mass of the partially purified enzyme was found to be 45 kDa by using SDS-PAGE. The protease enzyme that was partially purified from B. cereus was purified 1.2-fold after ammonium sulfate precipitation. The molecular mass of the partially purified enzyme was determined to be 37 kDa by using SDS-PAGE. 相似文献