共查询到20条相似文献,搜索用时 31 毫秒
1.
N. Kimura 《Nuclear Physics B》1984,246(1):143-156
Masses of all the glueballs which are created by 6- or 7-link operators are calculated to order g?8 in pure SU(3) hamiltonian lattice gauge theory. Several low-lying states are found with masses (1 and 7 stand for radial excitations and ms is the mass of the lowest 0++ state), . These values are obtained at the point g?2 ? 0.8, which lies near the scaling region. 相似文献
2.
The electronic properties of single crystals of monoclinic SrAs3 have been studied by investigating the temperature dependence of electrical conductivity, Hall effect and Shubnikov de Haas (SdH) oscillations. At 4.2 K, SrAs3 is predominantly p-conducting with a typical hole concentration of 6 × 1017cm-3. The Hall coefficient changes its sign near 80 K. The angular dependence of the SdH oscillations was used to map out the shape of the Fermi-surface of holes. Two asymmetric, quasi-ellipsoidal Fermi-bodies are located in the first Brillouin zone. The cyclotron effective masses for two crystallographic directions were calculated from the temperature dependence of the amplitude of the oscillations: and , respectively. There are indications for a third Fermi-surface which is attributed to electrons. 相似文献
3.
The mobility μ of a very pure semiconductor at very low temperatures is investigated in terms of a model where electrons are scattered by charged impurities distributed uniformly in space, and the electron-electron interaction is taken into account by the Debye-Hueckel screening in the interaction potential. The equation for the current relaxation rate Γ, derived previously by the proper connected diagram expansion, incorporates the quasi-particle effect in a self-consistent manner. The solution of this equation at high carrier concentrations n yields the so-called Brooks-Herring formula. At lower concentrations, the solution deviates significantly from the latter. The solution is in general smaller than the standard expression for the rate based on the Boltzmann equation; and this is consistent with the existing conductivity data available. At the very low concentrations e.g. n = n3 = 1013cm?3 or lower for Ge, the mobility calculated is inversely proportional to the square-root of the impurity concentration ns, and has a -dependence (T: temperature). , where k is the dielectric constant. The conductivity data directly comparable with this formula are not available at present. However, the quasi-particle effect which led to this peculiar concentration-dependence should also show itself in the cyclotron resonance width; there, experiment and theory both show the -dependence for very pure semiconductors. 相似文献
4.
The low temperature mobility μ limited by charged impurities is calculated by solving the equation for the relaxation rate previously derived. The calculated μ behaves like In for lowest concentrations ns<1011cm?3 for Ge and for intermediate concentrations ns ~ 1012?1014cm?3. 相似文献
5.
The first observation of cyclotron resonance of holes in AgBr is reported. Measurements have been made at 34 GHz and 1.7 K. It is shown that the energy surfaces for the hole polaron consist of a set of spheroids oriented along the [111] directions with the mass parameters and . The mobility of the hole polaron is determined to be about at 1.7 K. 相似文献
6.
Infrared cyclotron resonance was observed in n-type InSb, GaAs and Ge in very high magnetic fields up to 1.3 MOe at room temperature using a CO2 laser. A large shift of the cyclotron mass due to the non-parabolicity of the energy band was found in each material. The band edge masses of electrons at room temperature were evaluated to be for InSb, m for GaAs and m for Ge. The linewidth was measured in GaAs and Ge in the high fields. 相似文献
7.
Marek Danielewski Jaeosław Da̧bek Stanisł;aw Mrowec Grażyna Siemińska 《Solid State Ionics》1985,17(4):331-335
Using the re-equilibration kinetic method the chemical diffusion coefficient in nonstoichiometric chromium sesquisulfide, Cr2+yS3, has been determined as a function of temperature (1073–1373 K) and sulphur vapour pressure (10?104 Pa). It has been found that this coefficient is independent of sulphur pressure and can be described by the following empirical equation: . It has been shown that the mobility of the point defects inCr2+yS3 is independent of their concentration and that the self-diffusion coefficient of chromium in this sulfide has the following function of temperature and sulphur pressure: . (cm2s?1). 相似文献
8.
Luminescence decay of isolated donor-acceptor pairs has been measured over the range of pair distance R ~ 180 Å in phosphorous-doped ZnTe. Analysis of the recombination rate as a function of the pair distance suggests an asymptotic behaviour of the acceptor envelope function of the type exp(-r/aA), with . This effective Bohr radius would correspond to an hydrogenic mass , which is close to the light hole mass as measured from cyclotron resonance experiments, . A discussion on the validity of the isolated donor-acceptor pair model is also given. 相似文献
9.
J. Leotin J.C. Ousset R. Barbaste S. Askenazy M.S. Skolnick R.A. Stradling G. Poiblaud 《Solid State Communications》1975,16(4):363-366
The first observation of cyclotron resonance in n-type GaP is reported. The electrons were thermally excited at a temperature of 100 K and the resonance was observed at submillimetre wavelengths (337 μm) using a pulsed magnetic field of 0–300 kG. From experiments with B∥〈100〉, 〈110〉 and 〈111〉 it was found that the transverse effective mass for electrons is and that the anisotropy factor for the conduction band ellipsoids is K = 20+10-6. 相似文献
10.
Dependence of static dielectric susceptibility and correlation length of charge density waves (CDW) with weak defects on parameter of incommensurability with lattice is investigated. In almost commensurate phase (h?hchc), and Rc ~ (h ? hc). In. Far from commensurability , , where a is the dimensionless ratio of random potential intensities, corresponding to backward and forward scattering impurities. 相似文献
11.
Using the proper connected diagram expansion which incorporates the quasi-particle effect in a natural manner, we calculated the cyclotron resonance width Γ and frequency shift Δ in the extreme quantum limit, (a) Δ = 0 for any form of interaction potential, (b) Γ ∝ nIB for a short range interaction, and (c) for the unscreened Coulomb interaction, are obtained in the weak coupling approximation. The result (a) and the field (B)- and concentration (nI)-dependence in case (b) are in satisfactory agreement with experimental data on the Si space-charge layers at the surface carrier densities higher than 1 × 1012cm-2 and at liquid helium temperatures, where the main source of relaxation is thought to arise from a short-range interaction. 相似文献
12.
Collisions between two excited atoms leading to an increase in the excitation energy of the particles have been under investigation. All measurements were made in the afterglow of gas-discharge plasma. The cross sections of the following reactions have been determined: . The cross section of the first reaction for different transitions lies in the region (2?35) × 10?15 cm2 and the cross section of the second, in (0.2?2.4) × 10?16 cm2. Possible systematic errors and the role of cascade transitions are discussed. Cross sections of the Penning reaction Hem + Xe0 → He0 + Xe+ + e have also been measured. The result is σ (23S) = (1.4 ± 0.2) × 10?15 cm2, σ (21S) = (1.2 ± 0.3) × 10?15 cm2. 相似文献
13.
EPR of 61Ni+ doped CuGaS2 at 4.2 K leads to the following experimental data: . High axial field splitting of 2T2 state stabilizes the center against Jahn-Teller interaction. Covalency reduction factor k is 0.76. 相似文献
14.
Based on the proper connected diagram expansion, we calculated cyclotron resonance widths Γn associated with neighboring Landau states (n, n +1) for free electrons in interaction with more than one kind of impurities. In 3D usual Matthiessen's rule Γn=Γ(1)n+Γ(2)n+…where Γ(i)n represent widths calculated separately for each kind, is obtained. In 2D a new rule: is obtained. 相似文献
15.
Self-diffusion of 59Fe parallel to the c axis in single crystals of Fe2O3 has been measured as a function of temperature (1150–1340°C) and oxygen partial pressure (2 × 10?3 ? pO2 ? 1 atm) The temperature dependence of the cation diffusivity in air is given by the expression .The unusually large value of D0 is interpreted in terms of the values of the preexponential terms in the reaction constants for the creation of defects in Fe2O3. The oxygen-partial-pressure dependence of the diffusivity indicates that cation self-diffusion occurs by an interstitial-type mechanism The simultaneous diffusion of 52Fe and 59Fe has been measured in Fe2O3. The small value of the isotope effect suggests that iron ions diffuse by an noncollinear interstitialcy mechanism, which is consistent with the crystal structure of Fe2O3. 相似文献
16.
17.
M.B. Gavela A. Le Yaouanc L. Oliver O. Pène J.-C. RaynaL T.N. Pham 《Physics letters. [Part B]》1982,109(3):215-220
In the Kobayashi-Maskawa model, penguin diagrams can induce CP violating phases in matrix elements of the type n→Λ. This produce a neutron electric dipole moment through subsequent parity violating radiative weak decay Λ→nγ. We can expect , three to four orders of magnitude bigger than the mechanism based on the transition quark electric dipole moment. The reason is essentially that the GIM cancellation comes in the Penguin case from as for the transition quark electric dipole moment. 相似文献
18.
H. Kleinert 《Physics letters. [Part B]》1976,62(1):77-80
In quark gluon theory with very small bare masses, -ψ, spontaneous breakdown of chiral symmetry generates sizable masses Mu, Md, Ms, … We find (. Scalar densities have well determined non-zero vaccum expectations at an SU(3) breaking of the vacuum c′ ≡ 〈0|u8|〉/〈0|uo|0〉 ≈ ? 16% 相似文献
19.
J.C.D. Brand U.D. Deshpande A.R. Hoy S.M. Jaywant 《Journal of Molecular Spectroscopy》1983,100(1):143-150
The E-B (0g+-0u+) band system of Br2 has been investigated at Doppler-limited resolution using polarization labeling spectroscopy. Merged E state data for the three naturally occurring isotopes in the range vE = 0–16, expressed in terms of the constants for 79Br2, are (in cm?1) Y0,0 = 49 777.962(54), Y1,0 = 150.834(22), Y2,0 = ?0.4182(28), Y3,0 = 6.6(11) × 10?4, Y0,1 = 4.1876(28) × 10?2, Y1,1 = ?1.607(16) × 10?4, and Y0,2 = 1.39(39) × 10?8. The bond distance is , and the diabatic dissociation energy to . 相似文献
20.
F. Varret 《Journal of Physics and Chemistry of Solids》1976,37(3):257-263
Pulsed field experiments up to 450 kOe have been performed on FeSiF6.6H2O. We interpret the data: (i) in terms of spin hamiltonian constants: D = 12.3± 0.2 cm-1 (E = 0.54cm-1 being known from EPR data); (ii) in terms of axial-crystal-field parameters: . The magnetic axis is found to deviate from the cristallographie c axis by an angle 1° < θ < 2°. The adiabatic cooling obtained during the pulse is discussed.Similar experiments on Fe0.15Zn0.85SiF6.6H2O and Fe0.30Zn0.70SiF6.6H2O single crystals are reported; in both cases we measure . Using EPR data, we obtain D = 14.3cm-1, λ ~ ?75cm-1, δ ~ 195cm-1; using Mössbauer data, we obtain D = 15.3cm-1, λ ~ ?88cm-1, δ ~ 185cm-1. 相似文献