共查询到20条相似文献,搜索用时 31 毫秒
1.
A. Jamiołkowski 《Reports on Mathematical Physics》1974,5(3):415-424
Let 1 be the algebra of linear operators on the n-dimensional Hilbert space 1, and let 2 be the algebra of linear operators of the m-dimensional Hilbert space 2. Let (1, 2) denote the complex space of linear maps from 1 to 2. By a positive map we mean an element of the space (1, 2) (superoperator with respect to 1) which maps positive definite operators in 1 into positive definite operators in 2. The aim of this paper is to present an effective method which allows to verify whether a given superoperator Λ∈(1, 2) is a positive map. Besides that necessary and sufficient conditions for the positive definiteness of even-degree forms in many variables are given. 相似文献
2.
C.R. Jungmann H. Weigmann L. Mewissen F. Poortmans E. Cornelis J.P. Theobald 《Nuclear Physics A》1982,386(2):287-307
Neutron transmission experiments were performed on 32S between 0.18 MeV and 19 MeV and differential elastic scattering experiments up to 2 MeV. The resonance parameters, including spin and parity, were determined up to 1.7 MeV. The distribution of neutron strength was determined for s, P, P, d, d and f-wave levels, and is compared to recent model calculations. The isotopic purity of some possible isobaric analog states was deduced from their neutron widths. 相似文献
3.
The structure of the high-temperature solid solution Li1.6Ag0.4SO4 has been determined from neutron and X-ray powder diffraction data. The sulphate groups form a fcc lattice where the lithium ions are found to occupy the ±(, , ) tetrahedral sites. The silver ions partly occupy the same sites and partly the larger (, , ) octahedral site. The results strongly support earlier conclusions for the fcc phase of Li2SO4. Exceptionally high temperature factors are found. The consistency of the structural model with other characteristic properties of the high-temperature fcc phase is briefly discussed. 相似文献
4.
Core line asymmetries have been observed in the 3p, 3p, 3s, 2p and 2p XPS spectra of Ni. The asymmetry parameters are the same for all lines within the experimental accuracy. The absence of exchange splitting in the 3s line indicates a 3d10 configuration for the fully screened final state of Ni. 相似文献
5.
I. Reineck B. Wannberg H. Veenhuizen C. Nohre R. Maripuu K.-E. Norell L. Mattsson L. Karlsson K. Siegbahn 《Journal of Electron Spectroscopy and Related Phenomena》1984,34(3):235-252
The outer valence region in CS2 has been studied by high-resolution UV photpelectron Spectroscopy. The spectra reveal detailed vibrational structure in the X2Πg, A2Πu, B2Σ+u and C2Σ+g bands. Some of the fine-structure peaks in the XBand Cbands are shown to be pressure-dependent. The reason for the pressure dependence is assumed to be inelastic scattering of electrons emitted in the adiabatic transitions. It is established that the two CI satellite bands present in the He(I)-excited spectrum contain vibrational structure. 相似文献
6.
C.A. Van Dijk C.Th.J. Alkemade 《Journal of Quantitative Spectroscopy & Radiative Transfer》1980,23(4):445-449
Several resonances and underlying continua were observed in the excitation profiles of sodium atoms in an H2-O2-Ar flame, irradiated by the focused beam of a tunable, pulsed dye layer. These profiles are obtained by tuning the laser through the spectral range of Rhodamine 6G and detecting the ensuing fluorescence signals from the 3D-3P and 4D-3P transitions. We observed resonances corresponding to the 3S-3P, 3S-3P, 3P-5S, 3P-5S one-photon transitions and resonances corresponding to the 3S-5S, 3S-4D, two-photon transitions. The observed resonances result from different sequences of radiative and collisional excitation. The presence of the continua is explained by consecutive absorption of laser photons in the collisionally broadened wings of absorption lines. The spatial inhomogeneity of the laser beam and hence of the saturation causes submerging of some resonances into continua. 相似文献
7.
New measurements are reported of the magnetic susceptibility above the freezing temperature Tf for noble-metal spin-glasses with to 6 at.% Fe or Mn. The susceptibility for Tf<T?5 Tf is not Curie-Weiss, but local magnetic correlations manifest themselves and provide a key for the determination of the exchange interactions in spin-glasses. The exchange parameters Jn are resolved up to 5 neighbors for Fe, Mn, Mn and Mn through a configuration ensemble calculation which includes atomic short range order. 相似文献
8.
R. Pfranger D. Płusa S. Szymura B. Wysłocki 《Journal of magnetism and magnetic materials》1980,21(1):43-46
The domain structure of the compounds Dy2Fe17 was determined by the powder pattern method. The dependence of the mean domain width on the mean grain thickness is described by . The magnetic anisotropy constant K1, the Bloch wall energy γ and the Bloch wall width δ for polycrystalline Dy2Fe17 compounds are also determined. 相似文献
9.
The anomalous dispersion of the [001] transverse phonon branch of Nb0.9Zr0.1 and Nb0.8Zr0.2 has been measured by neutron inelastic scattering. The anomaly is found to become less pronounced as the Zr content of the alloy is increased. Although the anomaly is strongly temperature-dependent it is not obviously affected by the superconducting transition. Diffraction measurements with the Nb0.9Zr0.1 sample show the diffuse scattering which Wakabayashi has recently reported to occur at wave-vectors around [,,] in a 12% alloy. The Nb0.8Zr0.2 crystal however displays unbroadened superlattice peaks at wavevectors [,, in some Brillouin zones. 相似文献
10.
The resonant loss in LiNdP4O12 (LNP) lasers has been investigated. The effective resonant loss coefficient for the 1.047(7) μm laser emission was measured to be 0.042 cm-1. This value can be explained by resonant absorption due to the 4I1→4F transition including the reabsorption effect of the fluorescence resulting from the 4I→4F transition. 相似文献
11.
The decay of the 4G state of Nd3+ in LaCl3 and La(Cl99.6 Br0.4)3 was measured after pulsed laser excitation as a function of temperature. The decay rate is shown to depend besides the radiative transition on single-phonon relaxation between the states 4G () and 4G () and on multiphonon orbit-lattice relaxation from 4G to 2G. Partial substitution of Cl by Br only alters the radiative lifetime. 相似文献
12.
D. Moses A. Denenstein A. Pron A.J. Heeger A.G. MacDiarmid 《Solid State Communications》1980,36(3):219-224
The temperature dependences (0.8 K ? T < 7 K) of the specific heats of pure polyacetylene (both and isomers) and heavily doped metallic [CH(AsF5)0.12]X are reported. Results for undoped -(CH)X indicate behavior typical of crystalline polymers, whereas isomerization to the -form leads to a small term linear in temperature signifying increased disorder. Comparison of the data from and starting material indicates that isomerization is induced during doping. The increased coefficient of the linear term in the metallic polymer is discussed in terms of two contributions; an electronic term expected for a metal, and the increased effect of disorder in the doped polymer. 相似文献
13.
Argon crystals were doped with 0.2 ppm of 41K through the nuclear reaction 40Ar (n, β-) 41K. The absorption spectrum from 300 nm to 800 nm was measured as a function of the annealing temperature. Absorption ← 42s transition of the free atom could be bands corresponding to the 42p, ← 42s and 52p, ← 42s transition of the free atom could be observed. The absorption bands depend strongly on the annealing temperature. An increase in the annealing temperature results in a blue shift of the absorption bands. 相似文献
14.
Energy levels in the N = 83 nucleus 149Dy were studied by the reaction 152Gd(α, 7n) at 106 MeV bombarding energy using in-beam γ-ray spectroscopy methods. The measurements identified three isomers in this nucleus, at 1073 keV (13 ± 3 ns), at 2700±150keV (5 μs < T < 0.5 s), and above 3.5 MeV (50 ± 15 ns). The low-lying isomer is interpreted as i. The configuration ?(πh2)10+ ×vf is suggested for the state at 2.7 MeV. 相似文献
15.
The fluorescence spectra and lifetimes of low lying states of Er3+ in Cs2NaErCl6 single crystals have been investigated at room temperature and at 77 K. The assignments of the 4F-4I and 4I-4I phonon-assisted transitions have been proposed. The fluorescence lifetimes of low lying fluorescing levels have been estimated. 相似文献
16.
The differential cross section and polarization for neutrons scattered from 10B have been measured at En = 2.63 MeV (Ex = 13.85 MeV). The results of this experiment and other available neutron scattering data in the range 1 < En < 4 MeV are interpreted through a single-level R-matrix calculation over the region 12 < Ex < 15 MeV. Based on this analysis the most probable Jπ assignment for the 14.0 MeV level in 11B is . The anomaly near Ex = 13.1 MeV can only be explained in terms of two overlapping levels having assignments of (, )? and (, , )+. 相似文献
17.
Using the light absorption technique in a 132Xe afterglow plasma, we have measured the relative transition probabilities for several xenon lines which have the metastable 6s[]2 or the resonant 6s[]1 states as their lowest transition level. Because the transition probabilities of the 8819 Å (6p[]3 ? 6s[]2) and 8280 Å (6p[]0 ? 6s[]1) lines are relatively well known, we have chosen these as reference lines and have thus been able to determine the absolute values of the transition probabilities for 19 xenon lines corresponding to transitions from 6p, 6p′, 7p, 8p, 9p, 4f and 5f to 6s[]2, and for four lines corresponding to the transitions 6p?6s[]1. 相似文献
18.
LiFeCl4 and AgFeCl4 are obtained by direct reaction between LiCl or AgCl and FeCl3 at 300°C and 400°C respectively. Both compounds are monoclinic with , , , β = 92° (30') for LiFeCl4 and , , , β = 106° (1) for AgFeCl4.LiFeCl4 is clearly isotypic of LiAlCl4. Magnetic measurements characterize in both cases Fe3+ ions in a high spin tetrahedral situation. LiFeCl4 becomes antiferromagnetic at low temperature (TN?10 K). AgFeCl4 reveals a more complex situation. On contrary to the silver derivative, LiFeCl4 is a good ionic conductor with activation energy of 0.78 eV in the solid state below 105°C, and a sharp increase in the lithium mobility at this temperature. 相似文献
19.
S. Pruski 《Reports on Mathematical Physics》1980,17(3):419-436
The orthogonal projectors from the space (n) of n-fermion operators onto its sub-spaces p(n) consisting of p-reducible elements of (n>), as well as those from (n) onto p(n)?p?1(n) are constructed. Using the above projectors the inverse problems of contraction and expansion are solved. 相似文献
20.
In search for structural contributions to the low temperature anomaly we report high resolution resistance and magnetoresistance measurements () of amorphous splats of Gd67Co33 and Pd80Si20. For both alloys, the resistivity ?(H = 0, T) has a minimum at T ~ 10 K and increases with decreasing T. The ferromagnetic Gd67Co33 shows a strong negative field dependence of , saturating at H ~ 2T for T = 4.2 K but no measurable change in below 10 K is observed.The diamagnetic Pd80Si20 exhibits a positive field dependent magnetoresistance at low temperatures. Additionally, a field dependent part in is found which is probably due to paramagnetic impurities (~ 1 ppm Fe). However, there is also a field independent contribution in the amorphous state of Pd80Si20, which vanishes after crystallization. We attribute this to non-magnetic scattering induced by the disordered structure. 相似文献