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91.
We have studied the high-pressure phase stability of LaF3 using full-potential linear augmented plane wave method. We have shown that experimentally observed orthorhombic phase is less stable compared to the theoretically predicted tetragonal structure above 25 GPa pressure. The structural transition is mainly due to the steric repulsion of ions and electrons to higher pressures. 相似文献
92.
V. Dose Th. Fauster R. Schneider 《Applied Physics A: Materials Science & Processing》1986,40(4):203-207
The energy resolution of a VUV isochromat spectrometer employing the traditional energy selective Geiger counter can be significantly improved. The variance of the optical resolution function with the usual CaF2 entrance window is (240 meV)2. With SrF2 we obtain (113 meV)2 at room temperature and (73 meV)2 at 70°C. A direct confirmation of these data, which were derived from a moment analysis of the threshold behaviour of an Au isochromat is provided by a measurement of image potential states at Cu(001). 相似文献
93.
T. Jeong 《Solid State Communications》2007,141(6):316-319
The electronic band structure of CeCoGe3 has been calculated using the self-consistent full potential nonorthogonal local orbital minimum basis scheme based on density functional theory. We investigated the electronic structure with the spin-orbit interaction and on-site Coulomb potential for the Ce-derived 4f orbitals to obtain the correct ground state of CeCoGe3. The exchange interaction between local f electrons and conduction electrons play an important role in their heavy fermion characters. The fully relativistic band structure scheme shows that spin-orbit coupling splits the 4f states into two manifolds, the 4f7/2 and the 4f5/2 multiplets. 相似文献
94.
The structure, magnetic property and magnetocaloric effect of GdCo2−xAlx (x=0, 0.06, 0.12, 0.18, 0.24, 0.4) compounds have been investigated by X-ray diffraction (XRD) and magnetic measurement techniques. The experimental results show that the GdCo2−xAlx (x≤0.4) compounds are single phase with a Laves-phase MgCu2-type structure. The Curie temperature Tc initially increases, and then decreases with increasing Al content. The maximum value of Tc, 418 K, is reached for the compound with x=0.06. The magnetic entropy change, which is determined from the temperature and field dependence of the magnetization by the Maxwell relation, decreases almost linearly with increasing Al content. 相似文献
95.
96.
K. Fuke F. Misaizu M. Sanekata K. Tsukamoto S. Iwata 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1993,26(Z1):180-182
Electronically excited states of magnesium-water cluster ions, Mg+(H2O)
n
,n=1–5, are studied by photodissociation after mass selection. The observed photodissociation spectra are assigned to the2P–2S type transitions localized on the Mg+ ion with the aid of ab initio CI calculations. In addition to evaporation of water molecules, photoinduced intracluster reaction to produce MgOH+(H2O)
n
is found to occur efficiently, with pronounced size dependence. The intriguing features observed in the mass spectrum of nascent cluster ions are discussed in relation to the stepwise solvation of this reaction. 相似文献
97.
Deviations from the ideal quadrupole potential in a Paul ion trap create nonlinear resonances at certain operating points inside the stability diagram, where in the absence of potential pertubations storing times are very long. In the presence of those pertubations, however, the ions are lost from the trap. Since these resonances are mass dependent and the mass resolution is of the order of 100 it can be used to separate isotopes of a given element by choosing suitable trap operating conditions. Experiments on a natural mixture of Eu+ ions of mass 151 and 153 show that in a simple way, by proper choice of the operating point, the ions can be completely separated and laser-induced optical spectra of a single isotope can be received. This is the first time that mass separation in a Paul trap is performed by nonlinear effects in contrast to the usual way of using the mass dependent boundaries of the stability diagram 相似文献
98.
Photdetachment of a negative HF^- ion in an electric field is studied by using the two-centre model and the closed orbit theory. An analytic formula is presented for the electron flux of HF^- in the presence of an electric field. The results show that the oscillation in the electron flux distribution is caused by the rescattering effect of the molecular ion core and the interference between the two nuclei. In addition, the interference between the orbits passing through the given spatial point also plays an important role in the electron flux distribution. This study provides a new understanding of the photodetachment of polar molecules in the presence of external field. 相似文献
99.
Microwave magnetic properties are studied for rhombohedral structure Nd2Fe17N3-δ with planar magnetic anisotropy. Its resin composites show the permeability μ'0 = 4.15 at low frequency, the natural resonance frequency fT = 1.71 GHz and the resonance bandwidth 6.66 GHz. The calculated static permeability of Nd2Fe17N3-δ reaches 133. The microwave magnetic properties are determined by the c-axis anisotropy field, basal plane anisotropy field and high saturation magnetization. Based on microwave measurement and theoretical fitting on complex permeability spectra, Nd2Fe17N3-δ may be a promising microwave absorber with bandwidth wider than traditional hexaferrites materials in GHz ranges. 相似文献
100.
U. Krönert St. Becker Th. Hilberath H. -J. Kluge C. Schulz 《Applied Physics A: Materials Science & Processing》1987,44(4):339-345
Resonance ionization mass spectroscopy (RIMS) and pulsed-laser induced desorption (PLID) have been combined for ultrasensitive detection and spectroscopy of very small samples of refractive elements. The method has been tested and applied to laser spectroscopy of 5×109 atoms (1.5 pg) of195Au (T
1/2= 183d) implanted at the ISOLDE online mass separator with 60 keV into graphite. A pulsed thermal atomic beam was formed by laser desorption with a 10 ns NdYag laser pulse. Subsequently the atoms were photoionized in a three-colour, three-step resonant excitation to an autoionizing state. The selectivity was enhanced by a time-of-flight measurement of the photo ions. In resonance, one ion was detected per 105 atoms implanted resulting in a gain in detection efficiency by three orders of magnitude in comparison to the use of a continuous atomic beam. In the course of the experiments several unknown autoionizing states were found, and the lifetime of the 6d
2
D
3/2 state of gold was determined to be=10.7(6) ns. 相似文献