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41.
By using the Anderson model with a filled valence band, we calculate the core photoemission spectra of CeO2, and compare them with experimental results. It is shown that in the ground state of CeO2 the 4?0 and 4?1 configurations are mixed strongly due to the large hybridization between the 4? states and the valence band. In the final state of the photoemission, the 4?1 and 4?2 configurations are also mixed strongly due to the final state interaction coming from a core hole potential and the large hybridization. The fractional intensity of the 4?0 photoemission peak is considerably different from the weight of the 4?0 configuration in the ground state because of the strong final state interaction. 相似文献
42.
High-resolution vibrational electron energy loss spectroscopy, low-energy electron diffraction and Auger electron spectroscopy have been used to study the interactions of nitrogen with the Pd(110) surface. At 120 K, N2 is chemisorbed molecularly on the Pd(110) surface, and the (2 × 1)-N2 structure is formed. Most probably, the N2 molecules are chemisorbed in the on-top sites of the bulk-like Pd(110) surface in the upright-linear structure. The Pd---N2 bond energy is estimated to be ˜ 6 kcal/mol. The Pd---N2 and N---N stretching vibrations of N2 admolecules on Pd(110) are observed at 30 and 278 meV, respectively. The primary-energy dependence and angle dependence of their excitation cross sections agree reasonably well with the prediction of the dipole theory. The electron beam-induced effects are briefly discussed. 相似文献
43.
X-ray scattering has been studied above the critical ordering temperature, Tc (133°C), in b.c.c. α-phase V2D. At 140 and 200°C quite weak diffuse intensity was observed centered on the reciprocal lattice points of the ordered superlattice. This intensity is due to short-range order among deuterium atoms which induces a local or short-range modulation of the parent vanadium lattice and suggests the possibility of local octahedral D—D fluctuations building up well above Tc. 相似文献
44.
45.
We prove identities between integrated Ursell functions and derivatives of the pressure in the thermodynamic limit, for multicomponent classical spin systems which obey the Lee-Yang theorem and some form of Gaussian domination, when the susceptibility is finite (T>T
c). Following Refs. 3 and 4, we view the moment generating function of the magnetization as the inverse of an infinitely divisible characteristic function. Fluctuation susceptibility relations of all orders then follow by bounding the corresponding cumulants, taken in zero external field. High-order cumulants are bounded in terms of the susceptibility using Gaussian and Simon's inequalities for short-range interactions. 相似文献
46.
L. G. Marcassa V. A. Nascimento L. L. Caliri A. Caires D. V. Magalhães V. S. Bagnato 《Laser Physics》2006,16(12):1722-1725
In this paper, we report observation of an enhancement of the ground state molecule Rb2 formation in a Rb magneto-optical trap due to a photoassociation laser. Such an enhancement effect is due to flux enhancement of atomic pairs at short internuclear distances. Our experimental observations consist in the measurement of the molecular formation rate constant due to a probe laser as a function of the trap laser intensity. The results are compared with a simple semi-classical model, showing good agreement. We conclude that the production of cold Rb2 may be enhanced using appropriate laser parameters; this may be useful for future experiments involving production and trapping of ultracold ground state molecules. 相似文献
47.
Luis G.G.V. Dias da Silva Sergio E. Ulloa Tigran V. Shahbazyan 《Physica E: Low-dimensional Systems and Nanostructures》2006,32(1-2):37
We study the interplay between impurity scattering and Coulomb interaction effects in the absorption spectrum of neutral bound magnetoexcitons confined in quantum-ring structures. Impurity scattering breaks the rotational symmetry of the ring system, introducing characteristic features in the optical emission. Signatures of the optical Aharonov–Bohm effect are still present for weak scattering and strong Coulomb screening. Furthermore, an impurity-induced modulation of the absorption strength is present even for a strong impurity potential and low screening. This behavior is likely responsible of recent experimental observations in quantum-ring structures. 相似文献
48.
49.
H.-D. Pfannes D. S. Vieira Junior R. Paniago J. H. Dias Filho 《Hyperfine Interactions》2005,165(1-4):247-252
The formation of local moments and the effect of charge carrriers in dilute magnetic semiconductors can be well understood using local probe techniques like Mossbauer Spectroscopy. We report here on Mossbauer studies in the systems Fe0.008Ge1 ? x D x (D = As, Bi), Fe0.008Ge1 ? x In x , and Fe0.008Ge1 ? x Sn x . At room temperature magnetic interactions were observed for donor (D) impurities at the Fe site in the Fe0.008Ge system. No such magnetic ordering was observed for acceptor (In) or neutral (Sn) impurities. 相似文献
50.
An efficient method for preparation of 4,6 or 5,6 disubstituted 3-aminopyridazines was easily carried out starting from easily available 4-bromo-pyridazine-3,6-dione, and using combination of both amination and Pd(0) cross-coupling reactions under microwave irradiation. 相似文献