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排序方式: 共有178条查询结果,搜索用时 15 毫秒
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W. Bartel P. Duinker J. Olsson P. Steffen J. Heintze G. Heinzelmann R.D. Heuer R. Mundhenke H. Rieseberg B. Schürlein A. Wagner A.H. Walenta 《Physics letters. [Part B]》1976,64(4):483-487
Decays of the J/ψ (3.1) resonance into final states with two charged hadrons and two photons are investigated. Branching ratios for the decays J/ψ → ?π and J/ψ → γη′ are determined to be Upper limits for the same decay modes of ψ′ (3.7) are also determined. 相似文献
43.
Alfred B. Anderson Robin W. Grimes Arthur H. Heuer 《Journal of solid state chemistry》1984,55(3):353-361
A quantum chemical approach based on predominantly covalent “normalized ion energies” has been developed for estimating structures and energies for defect clusters in quenched nonstoichiometric wustite (Fe1?xO). Small defect clusters of zinc blende structure show special stability over other clusters considered. Of these, either a 13:5 or a 16:7 defect cluster (13 or 16 Fe3+ vacancies and 5 or 7 tetrahedral Fe3+ interstitials) have the proper structure and composition to account for the observed P′ and P″ phases in wustite. 相似文献
44.
The properties of template-directed nucleation are studied in the transition region where full nucleation control is lost and additional nucleation beyond the prepatterned structure is observed. To get deeper insight into the microscopic mechanisms, Monte Carlo simulations were performed. In this context, the previously used continuous algorithm [F. Kalischewski, J. Zhu, and A. Heuer, Phys. Rev. B 77, 155401, (2008)] was replaced by a discrete one to reduce simulation time and to allow more detailed calculations. The applied method is based on the assumption that the molecules on the surface occupy the sites of a simple fcc lattice. It is shown that a careful mapping of the continuous Monte Carlo technique onto the discrete algorithm leads to a good reproduction of the former results by means of the latter method. Furthermore, the new method facilitates the calculation of the spatial distribution of nuclei on the surface. This provides a detailed comparison with experimental data. 相似文献
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Phase-conjugating stimulated Brillouin scattering mirror for low powers and reflectivities above 90% in an internally tapered optical fiber 总被引:7,自引:0,他引:7
A novel low-power phase-conjugating mirror based on stimulated Brillouin scattering in a quartz fiber with an internal taper is reported. A peak-power threshold as low as 500 W and a maximum reflectivity of 92% were obtained with 30-ns pulses from a Q -switched Nd:YAG laser. The maximum peak powers of 130 kW demonstrated a dynamic range of 1:260. Reliable operation in both single- and multiple-longitudinal-mode operation was observed with conjugation fidelities larger than 95%. 相似文献
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The potential energy landscape (PEL) of binary Lennard-Jones (BLJ) mixtures exhibits local minima, or inherent structures (IS), which are organized into metabasins (MBs). We study the particle rearrangements related to transitions between both successive IS and successive MB for a small 80:20 BLJ system near the mode-coupling temperature TMCT. The analysis includes the displacements of individual particles, the localization of the rearrangements, and the relevance of string-like motion. We find that the particle rearrangements during IS and MB transitions do not change significantly at TMCT. In particular, an onset of single particle hopping on the length scale of the interparticle distance is not observed. Further, it is demonstrated that IS and MB dynamics are spatially heterogeneous and facilitated by string-like motion. To investigate the mechanism of string-like motion, we follow the particle rearrangements during suitable sequences of IS transitions. We find that most strings observed after a series of transitions do not move coherently during a single transition, but subunits of different sizes are active at different times. Several findings suggest that, though string-like motion is of comparable relevance when the system explores a MB and when it moves from one MB to another, the occurrence of a successful string enables the system to exit a MB. Moreover, we show that the particle rearrangements during two consecutive MB transitions are basically uncorrelated. In particular, different groups of particles are highly mobile. We further find the positions of strings during successive MB transitions weakly but positively correlated, supporting the idea of dynamic facilitation. Finally, the relation between the features of the potential energy landscape and the relaxation processes in supercooled liquids is discussed. 相似文献
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