共查询到20条相似文献,搜索用时 15 毫秒
1.
We report on the first measurements of the critical field Bc2 and the specific heat of Nb3S4, which is a linear structured compound with a superconducting transition temperature of 3.65 K. The angular dependence of Bc2 is well described by the effective-mass model. The ratio of the critical fields parallel and perpendicular to the c-axis gives a value of 4.6. The small value of the specific heat jump at can be explained with an anisotropic gap function. 相似文献
2.
The deviations from the exponential decay law of the states of the Dirac hydrogen atom with respect to the transition are numerically estimated. We find |a0(t) ? exp(?λt)|?2.5 × 10?4 for all t, where a0(t) is the “exact” decay amplitude and λ is a complex constant such that (2Re λ)?1 is the “natural lifetime” of the states with respect to the spontaneous transition to . 相似文献
3.
Measurements of the temperature and pressure dependences of the resistivity of the pseudo-one-dimensional ternary compound Tl2Mo6Se6 are presented. We find that the conductivity parallel to the highly conducting c-axis is enhanced by pressure and the superconducting transition temperature Tc is suppressed by pressure at a rate kbar?1. These results are discussed in relation to the current models of transport in one-dimensional conductors. 相似文献
4.
Keu Hong Kim Jong Ho Jun Jae Shi Choi 《Journal of Physics and Chemistry of Solids》1985,46(10):1173-1178
The electrical conductivity of the system Y2O3CeO2 was measured in the temperature range 500–1100°C and Po2 range 10–7?10?1 atm. Possible defect models were suggested on the basis of conductivity data, which were investigated as a function of temperature and of Po2. The observed activation energies were 0.40 eV and 1.79 eV in the low- and high-temperature regions, respectively. The observed conductivity dependences on Po2 were in the temperature range 500–750°C and at temperatures from 750–1100°C. It is suggested that the system Y2O3CeO2 shows a mixed ionic plus hole conduction due to an O″i defect and an electronic hole conduction due to a V'''Y defect in the low- and high-temperature regions, respectively. 相似文献
5.
B. Jimenez C. Alemany J. Mendiola E. Maurer 《Journal of Physics and Chemistry of Solids》1985,46(12):1383-1386
The ferro-paraelectric transition in Sr0.5Ba0.5Nb2O6 ceramics has been studied by measuring the dielectric pennitivity as a function of temperature at different frequencies. Experimental results in the transition region over ?'max fit the relation with γ > 1, as is typical for dif transitions. In an interval of temperatures of 17°C over T0 (=Tfor?'max), γ = 2. Using the relaxors' model of Kirillov-Isupov an equation is inferred in order to compute the activation energy of the relaxors as a function of parameters directly obtained from the experimental results. 相似文献
6.
The 2Πu-X2Πg transition in Br2+ was reexamined using dispersed laser-induced fluorescence, and emission spectroscopy in a seeded molecular beam. New constants are derived, confirming the large difference between and , and reconciling the emission spectrum with photoelectron data. 相似文献
7.
G. Carboni G. Gorini E. Iacopini L. Palffy F. Palmonari G. Torelli E. Zavattini 《Physics letters. [Part B]》1978,73(2):229-231
The measurement of the energy transition in muonic helium is presented. The energy difference S1 is found to be Sexp1 = 1381.3±0.5 meV. This result agrees with the expected value obtained assuming the previously measured value for the energy difference. 相似文献
8.
The effective vibration-rotation Hamiltonians complete to fourth order in the Amat-Nielsen scheme for the upper states of the ν1, ν3, 2ν2, ν2 + ν4, and 2ν4 bands in methane are reviewed, and the major vibration-rotation interactions (H30, , , , ) connecting the different vibrational states are discussed. Explicit matrix elements in a basis of harmonic oscillator-symmetric rotor basis functions are given for the purely vibrational terms and for the vibration-rotation interactions. Expressions for spectral intensities of infrared and Raman spectra are presented, and the selection rules and transition moment matrix elements are stated. A computer program is described which, incorporating all these features, can be used for prediction of infrared and Raman spectra and for determination of molecular constants from observed spectra by a least-squares routine. As an example the program is applied to the 2ν4 isotropic Raman spectrum of 12CH4, leading to a very good agreement between the experimental and calculated spectra. 相似文献
9.
The absorption and MCD spectra of the , , and spin-allowed transitions of Cr3+ in K2NaGaF6 are reported. It is shown that transitions to the . states are induced by T1u vibratio the other spin-allowed transition, , there are three competing intensity mechanisms: electric dipole induced by T1u vibrations, electric dipole induced by T2u vibrations and magnetic dipole, and an estimate is made of the relative importance of these. The magnetic dipole zero-phonon line is observed to be accompanied by a vibrational sideband for which the coupling is predominantly with T2u vibrations. Other weak transitions are observed in MCD spectra and their origin briefly discussed. 相似文献
10.
The charge density wave transition in 2H-TaS2near 75 K has been observed to be incommensurate, using electron diffraction, with along the 〈10.0〉 directions which, within the experimental uncertainty, remains temperature independent to about 14 K. Incommensurate charge density formation is also observed in AgxTaS2 samples for with an increase in q1 to when x?0.26. Within the experimental error q1 appears to be temperature independent to 25 K. 相似文献
11.
The infrared absorption spectrum of a single crystal of MoSe2 is reported. A damped oscillator fit to the fundamental band gives the transverse optic frequency, at 300° K and at 77° K. The static and high frequency dielectric constants have been determined as Ks = 16.81 and K∞ = 10.24 respectively. An absorption band appears in the i.r. spectrum at 482 cm-1, and has been attributed to the oxygen impurity in the crystal. 相似文献
12.
F. Azaiez S. Fortier S. Galès E. Hourani J.M. Maison J. Kumpulainen J.P. Schapira 《Nuclear Physics A》1985,444(3):373-401
The γ-decay of the deeply-bound hole states in 111Sn has been investigated at 32 MeV incident energy by means of the 112Sn(3He, αγ) reaction. The α-particles emitted near 0° were detected in a Si counter located at the image plan of the superconducting solenoidal spectrometer SOLENO. The γ-rays in coincidence with the α-particles were detected by two Ge(Li) detectors located at 90° and 142° with respect to the beam direction, respectively. Energies, spins and decay schemes have been established for the low-lying states up to 2.5 MeV excitation energy in 111Sn. The γ-decay of the broad bump, located around 4.2 MeV and previously attributed to neutron pick-up from the inner neutron. Subshells, reveals the importance of quasiparticle-phonon m the spreading mechanism of the inner-hole strengths. The and 2p strength functions have been deduced from the α-decay of the enhanced structures (3 ≦ Ex≦ 8 MeV). They are compared to the ones measured in previous inclusive neutron pick-up experiments and to those calculated in the framework of the quasiparticle-phonon nuclear model. 相似文献
13.
Spin lattice relaxation T1 of naturally abundant 13C nuclei in squaric acid was measured close to the antiferroelectric-paraelectric phase transition temperature Tc = 373 K. A rapid increase in is observed close to Tc coming from above, which follows the power law where . This behaviour is explained on the basis of the two-dimensional character of the fluctuations. 相似文献
14.
S. Cochavi S. Gilad M.A. Moinester J. Alster M. Buenerd P. Martin 《Nuclear Physics A》1974,233(1):73-80
The 91Zr(d, 3He) reaction was studied at a deuteron energy of 28 MeV. Angular distributions were measured from 13° to 47°; lp values were extracted for the prominent lines of 90Y. The lp values and transition strengths were determined by DWBA analysis. The angular distributions for the doublet (g.s. and 0.20 MeV state) exhibit the characteristic l = 1 shape. States at 1.42, 1.57, 1.64 and 1.81 MeV were also populated strongly in the (d, 3He) reaction; the 1.42, 1.57 and 1.81 MeV levels contain l= 1 transition strength and are most likely members of the multiplet. The 2.03 MeV state has a characteristic l = 3 angular distribution and is suggested to be the only member of the sextet to be unambiguously observed in this study, most probably the 5? or 4? member. The members of the sextet were populated weakly (less than 100 μb/sr) in this reaction. 相似文献
15.
Energy curves and transition moments of the excited valence states of Hg2 were obtained in a model calculation based on calculated Mg2 energy levels and the assumption that the asymptotic spin-orbit matrix elements for the Hg atom are applicable to the molecular states. The spin-orbit and orbital-rotational interaction of the excited states of Hg2 is analyzed in both a Hund's case (c) and (a) representation. The intermediate (a) → (c) transition moments are obtained as a function of the internuclear distance. The effect of the orbital-rotational interaction which introduces Hund's case (b) and (e) couplings is found to be small for transitions among excited states under the conditions normally encountered for populating excimer states.Using the energy level positions and transition moments, the observed spectra and predicted spectra are compared for both radiative transitions including the ground state and among the excited states. The lifetime of the excimer state is calculated to be 1.4 μsec with the 335 nm band assigned to the transition. The 485 nm bands cannot be assigned to any Hg2 transitions. Strong bound-continuum absorptions are predicted for the 485 nm bands. On the other hand, the 335 nm emission is predicted to be absorbed by bound-bound transitions only. 相似文献
16.
The anisotropic magnetostriction of FeGe2 is measured for magnetic field along the [1 0 0] and [1 1 0] axes at temperature 4.2 K and along [1 0 0] from 77 to 300 K. The behaviour is consistent with spin reorientation in the basal plane. The saturation magnetostriction and the characteristic field required to produce saturation decrease with increasing temperature and approach zero at the lower transition temperature, K. This suggests that the spins flip from the basal plane into the direction of the tetragonal [0 0 1] axis at TK. 相似文献
17.
Eight P-branch transitions from the difference band of C2D2 have been observed in the microwave region. Significant improvements in the spectroscopic constants for the two states involved in the difference band have been obtained by combining infrared and microwave data. The Stark shifts for the observed C2D2 lines are discussed in some detail. The vibrational transition moment is found to be μvib = 0.0358 ± 0.0020 D. 相似文献
18.
A.R.W McKellar 《Journal of Molecular Spectroscopy》1981,86(1):43-54
Magnetic dipole transitions between the and components of the ground electronic state of BrO have been detected using the technique of laser magnetic resonance on three CO2 laser lines between 964 and 970 cm?1. This is the first direct observation of the state in BrO. The spin-orbit splitting parameter, A, is determined to be ?967.9831(2) cm?1 for 79Br16O and ?967.9981(2) cm?1 for 81Br16O. Accurate values for the rotational constant , the hyperfine parameters () and d, the Λ-doubling parameter p, and the Zeeman parameter g| are also determined from an analysis of the measured spectra. 相似文献
19.
Michael J. Haugh Bruce S. Schneider Allen L. Smith 《Journal of Molecular Spectroscopy》1974,51(1):123-134
Relative emission intensities of sixteen bands of HCl+ (A2Σ+ - X2Πi), four bands of DCl+ (A2Σ+ - X2Πi), and 5 bands of HBr+ (A2Σ - X2Πi) have been made using both ion-beam excitation and microwave discharge sources. Intensities were determined by comparison with computer-generated spectra. Treatment of the data within the r-centroid approximation shows that in HCl+ the electronic transition moment decreases strongly at large [] but levels off at shorter . DCl+ data agree quantitatively with HCl+. The variation in the HBr+ moment is similar, with . 相似文献
20.
The magnetic structure of manganous acetate Mn(CH3COO)2, 4H2O has been solved by neutron diffraction. Manganous acetate crystallizes in the space group with Z = 6. Manganese atoms (in position 2a and 4e) are located in (100) planes. Below TN = 3.18 K this compound is antiferromagnetic in a zero applied field with the k vector [ 00]. The plane (100) is ferromagnetic. The magnetic group is . 相似文献