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1.
The electrical resistivity and Hall coefficient of Zn3P2 have been measured for single crystal and thin polycrystalline film samples which were annealed over a range of equilibrium vapor compositions and temperatures. The room temperature electrical resistivity of single crystal samples annealed at 573 K varied from approximately 105Ω-cm for single crystals heated in equilibrium with zinc to 10 Ω-cm for those annealed in a phosphorus rich ambient. Hall measurements indicate that a variation in carrier concentration is responsible for these changes. The experimentally observed dependence of carrier concentration [h° ], (cm?3) on phosphorus pressure is given by [h°] = 1.32 · 1016 [p(P4)]0.13 for samples annealed at 573 K. The experimentally determined pressure dependence is in good agreement with a model based on phosphorus interstitials acting as acceptors. The pressure and temperature dependence of the carrier concentration yield the equilibrium constant KI for the formation of interstitial phosphorus defects according to the reaction where . The accommodation of phosphorus interstitials is discussed in light of the crystal structure of Zn3P2. 相似文献
2.
We report the first piezomodulation spectrum of Cd1?xMnxTe. Signatures of the exciton transition and the internal transition of Mn++ are identified. The opposite signs of these signatures are attributed to the positive pressure coefficient of the direct interband transition as contrasted to a negative pressure coefficient for the transition causing the Mn++ feature. 相似文献
3.
F-type intervalley scattering in stressed silicon is studied by means of photoluminescence from “hot” and “cold” electron-hole drops and free excitons. The scattering rates are shown to be essentially determined by the impurity concentration before TA-phonons initiate complete thermalization among the electrons in the up- and down-shifted conduction valleys. For phosphorus donors, scattering probabilities of ? 2x10?6 are obtained. Much lower scattering probabilities are found for boron acceptors. 相似文献
4.
Isotope separation by laser deflection of an atomic beam, combined with simultaneous mass spectroscopy, has been used to determine optical frequency shifts and to assign mass numbers to all components of the 5536 Å resonance. Several components which cannot be resolved optically without the use of enriched samples, were resolved with the technique described. They are at 120 MHz, 136Ba at 128 MHz and 134Ba at 138 MHz. 相似文献
5.
Harry Partridge Charles W. Bauschlicher James R. Stallcop 《Journal of Quantitative Spectroscopy & Radiative Transfer》1985,33(6):653-655
Potential energy curves for the , and states of N+2 that dissociate to N () and , have been determined from a complete active space self-consistent field calculation. The state is found to be significantly bound (De = 2.68 eV) with a minimum at 1.72 Å. 相似文献
6.
Conductivity and optical data on a new organic, conducting charge transfer salt Δ2, 2′-Bi-(4,5-trimethylene-1,3-diselenole) 11,11′,12,12′-tetracyano-2, 6-napthoquinodimethane (HMTSF-TNAP) are given. . A maximum in σ(T) is found at TM = 47 K with σ(TM)/σ(300 K) = 6.0 ± 10%, and . σ(T) is well defined in the high temperature region, but is sample dependent at low temperatures. The optical data indicate a bandwidth and carrier density comparable to that of HMTSF-TCNQ. 相似文献
7.
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
8.
The electrical conductivity of polycrystalline LiNbWO6, which has a trirutile structure, was studied by the ac impedance method and dc resistance measurement. From the results, the following is clear; LiNbWO6 is a lithium ionic conductor, its electrical conductivity at 150°C is and the electronic transference number is about 0.03. 相似文献
9.
The complex polar Kerr effect (rotation and ellipticity) of magnetite single crystals has been measured at room temperature between 0.5 and 4.3 eV. From the magneto-optical data and the optical constants, the off-diagonal elements (?xy) of the dielectric tensor has been derived. Three well separated magneto-optical transitions have been indentified. At about 0.75 eV one strong magneto-optical structure with a diamagnetic line shape is assigned to a transition from Fe2+ in octahedral sites. Two other structures with paramagnetic line shapes near 1.85 and 2.90 eV are assigned to the orbital promotion processes and , respectively, which take into account Fe 3dn?1 final state effects. 相似文献
10.
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
11.
The polarized excitation and emission spectra of the U6+ molecular centers giving the most intense emission lines at 18 940 cm?1 and 19 285 cm?1 are presented and analyzed in detáil. From the polarization experiments, it is shown that the symmetry of the centers is C4v and that the symmetries of the observed electronic states are Γ2, Γ1 and Γ5. Finally, an electronic model is proposed which associates the emission and excitation lines of the U6+ centers in the visible region to transitions between the fundamental state and the states of the excited configuration . 相似文献
12.
L Nemes 《Journal of Molecular Spectroscopy》1978,72(1):102-123
Medium resolution infrared grating spectra of gaseous ketene, H2CCO were recorded between 1000 and 400 cm?1, both at instrument temperature (40°C) and with cooling (?40°C). Interferometric Fourier spectra were also measured at ?70°C with resolution 0.22 cm?1 between 450 and 330 cm?1. The K structure of the fundamentals ν5, ν6, ν8, and ν9 was assigned. These fundamentals are coupled by a-axis Coriolis interactions. These couplings were analysed on the symmetric top basis for setting up the perturbation matrix and by utilizing the K-dependent Coriolis shifts of levels. A preliminary analysis of the Coriolis intensity anomalies was also undertaken.Band center values from combination differences are and . Synthetic spectra indicate the band origins of ν8 and ν9 to be close to 977.8 and 439.0 cm?1, respectively. Estimates of Coriolis coupling constants obtained from synthetic spectra are , , , and . Approximate ratios of unperturbed vibrational transition moments obtained from spectral simulations are . 相似文献
13.
M. Villedieu N. Devismes A.M. de Goër 《Journal of Physics and Chemistry of Solids》1977,38(9):1063-1070
The effect of γ irradiation at 300 K on the concentrations of vanadium ions V3+, V4+ and V2+ in Al2O3 has been studied quantitatively, using three techniques: optical absorption (V3+), low temperature thermal conductivity measurements (V4+) and EPR (V2+). Several single crystals of Al2O3 doped with vanadium in a large range of concentration have been measured. The evolution of the respective concentrations by γ irradiation as a function of the total vanadium content C is quite different in the two regions and C larger than this value. A consistent analysis of the results has nevertheless been achieved, leading to the determination of the absolute concentrations of the three ions in the as-received and γ irradiated states for all samples with (room temperature annealing is observed above this value). The concentrations of V4+ and V2+ ions are always small, but V4+ ions are more stable: they are present in the as-received state at a level of 1% of the total concentration and a maximum value of is observed in the γ irradiated state; on the other hand there are less than 4.7 × 1015V2+ ions per cm3 in the as-received state and the maximum value is only . Charge transfer between V ions only is not sufficient to explain the experimental results and other defects must be involved in the γ irradiation effect. 相似文献
14.
Peter Zimmermann Theodore W. Ducas Michael G. Littman Daniel Kleppner 《Optics Communications》1974,12(2):198-201
We present a new technique for selectively populating excited states which are inaccessible by dipole excitation from the ground state. The method uses a static electric field to introduce a component of a dipole-allowed state into the state of interest. We have applied the method to cesium to measure lifetimes and a Stark mixing coefficient. The results are , , and <62D|;ez |72P>/(E7P?E6D)=0.7(3)×10?3 where is in kV/cm. 141 相似文献
15.
Excitation functions at θ = 90° have been measured for , , and , in the range E3He = 3–19 MeV. The first reaction has also been studied at θ = 40°. Excitation functions at 90° have also been measured for and for E3He = 19–26 MeV. Angular distributions have been measured for the first four reactions.For the most excitation functions, a broad peak is observed, several MeV wide, centred at about Ex≈ 20 MeV. Superimposed on this, in some cases, are narrower peaks, with width ≈ 1 MeV. Energies and widths have been extracted for all resonances.Cluster-model calculations have been carried out, using methods similar to those which have proved successful for low-lying states in A= 18–19 nuclei. No satisfactory correspondence with the present results was found. The shell model has been used to calculate Γ3He and Γγ for 1?ω excitations in the final nuclei. These generally show good agreement with the trends of the experimental data. The results are consistent with the excitation of the giant dipole resonance in 3He capture, but much more weakly than in proton capture. 相似文献
16.
The emission of Ni2+ ions in MgO, KMgF3, KZnF3 and MgF2 crystals has been investigated. The fine structure on the bands at about 20 000 cm-1 and 13 000 cm-1 has been studied in detail and from this and the excitation spectra these bands are assigned to and transitions respectively. 相似文献
17.
Mass separated radioactive 133Ba has been investigated by means of optical spectroscopy. From hyperfine structure and isotope shift we obtain the nuclear magnetic moment μI = ?0.769(3) μn and the change of the nuclear mean square charge radius . 相似文献
18.
A. Bolovinos P. Tsekeris J. Philis E. Pantos G. Andritsopoulos 《Journal of Molecular Spectroscopy》1984,103(2):240-256
Absolute extinction coefficient and oscillator strength of pyridine, pyrimidine, pyrazine, and s-triazine were recorded with moderate resolution in the region of 3.5–9.5 eV. Analogous to , 1B1u, transitions of benzene, several and Rydberg transitions are presented and discussed. 相似文献
19.
S.L. Mair 《Solid State Communications》1984,52(3):335-337
The rectilinear and angular mean-square displacements of the atoms in K2SnCl6 have been measured from 293 to 450 K using single-crystal X-ray diffraction. The motion of the tin and chlorine atoms has been found to consist, essentially, of rigid-body translation and libration of the SnCl6 octahedra. The root-mean-square angle of libration of the SnCl6 octahedra, , ranged from 5.7 to 6.1°. The slow variation of with temperature, together with the measured non-zero value of one of the fourth cumulants of the chlorine atom displacement, are indicative of highly non-linear coupled motion associated with the soft-mode phase transition at 261.5 K. 相似文献
20.
Electron and hole-drift velocity is measured in the layer semiconductors HgI2, GaSe, PbI2 and GaS, mainly on the direction parallel to the c-axis between 80 and 400 K. In the electric field range in question, electron and hole-drift velocity is proportional to the field except in the case of GaS, where a superohmic behaviour is observed. At 300 K the mobility parallel to the c-axis is , for HgI2; , for GaSe; , for PbI2. The highest hole mobility observed in GaS is .Where it is possible to compare these data with mobility values perpendicular to the c-axis, the three-dimensional character of the energy bands near the fundamental gap is proved.For HgI2 and GaSe we find no evidence for the large anisotropy of charge-carrier transport properties usually attributed to layered semiconductors. The mobility-temperature dependences found are interpreted on the basis of polar and non-polar optical phonon scattering mechanisms, except in the case of GaS, where a trapping model is used. The effective masses of electrons and holes are reported for PbI2 and, for the first time, for HgI2. 相似文献