排序方式: 共有23条查询结果,搜索用时 15 毫秒
21.
G Viesti M Lunardon D Fabris G Nebbia M Cinausero E Fioretto G Prete JB Natowitz K Hagel R Wada 《Pramana》1999,53(3):395-404
The transition of the level density parameter a
off from the low excitation energy value a
off=A/8 MeV−1 to the Fermi gas value a
FG ∼ A/15 MeV−1 was discovered a few years ago studying particle spectra evaporated from hot compound systems of A∼ 160. A number of experiments have been recently performed to confirm the earlier findings and extend the investigation to
other mass regions and to higher excitation energies. Furthermore, precision coincidence experiments have been done in the
lead region in which evaporation residues are tagged by low energy gammarays. Those experiments open the possibility of a
detailed study of the level densities in nuclei where the shell effects are important. 相似文献
22.
Kaiser AM Gray AX Conti G Son J Greer A Perona A Rattanachata A Saw AY Bostwick A Yang S Yang SH Gullikson EM Kortright JB Stemmer S Fadley CS 《Physical review letters》2011,107(11):116402
Standing-wave-excited photoemission is used to study a SrTiO3/LaNiO3 superlattice. Rocking curves of core-level and valence band spectra are used to derive layer-resolved spectral functions, revealing a suppression of electronic states near the Fermi level in the multilayer as compared to bulk LaNiO3. Further analysis shows that the suppression of these states is not homogeneously distributed over the LaNiO3 layers but is more pronounced near the interfaces. Possible origins of this effect and its relationship to a previously observed metal-insulator-transition in ultrathin LaNiO3 films are discussed. 相似文献
23.
J. B. Kortright O. Hellwig D. T. Margulies Eric E. Fullerton 《Journal of magnetism and magnetic materials》2002,240(1-3):325-330
Resonant small-angle scattering at the 2p levels of 3d transition elements strongly enhances scattering from both magnetic and chemical structure in the plane of thin films, as recently demonstrated for Co/Pt multilayers having perpendicular anisotropy. Here this resonant enhancement is demonstrated for CoPtCr films having in-plane magnetic anisotropy. A simple formalism describing the spectral dependence of the kinematical scattering provides a means to distinguish between magnetic and charge scattering and to probe the chemical segregation processes yielding charge scattering, thereby providing new information about this structure. It is found that correlation lengths of magnetic scattering are roughly 5 times larger than those for chemical scattering in the as-deposited CoPtCr film studied, consistent with significant exchange-coupling between polycrystalline grains. 相似文献