共查询到20条相似文献,搜索用时 78 毫秒
1.
The sound velocities in GeS2 glass have been measured by means of ultrasonic interferometry as a function of temperature or pressure up to 1.8 kbar. The bulk modulus Ks = 117.6 kbar and shear modulus G = 60.60 kbar were obtained for GeS2 glass at 15°C and 1 atm. The temperature derivatives of both sound velocities and elastic moduli are negative : p = °C, p = °C and p = , p = ?1.23 × 10?2 kbar/°C, p = ?2.93 × 10?2 their pressure derivatives are positive: T = 4.43× 10?2km/kbar, T = and (?Ks?P0)T=6.81, = 1.03, (?Y?TT= 3.57. The Grüneisen parameter, γth= 0.298, and the second Grüneisen parameter, δs = 3.27, have also been calculated from these data. The elastic behavior of GeS2 glass has proved to be normal despite the structural similarity among the tetrahedrally coordinated SiO2, GeO2 and GeS2 glasses. 相似文献
2.
The Raman active fundamentals ν1(A1g), ν2(Eg), ν5(F2g), and the overtone 2ν6 of SF6 have been investigated with a higher resolution and the band origins were estimated to be: ν1 = 774.53 cm?1, ν2 = 643.35 cm?1, ν5 = 523.5 cm?1, and 2ν6 = 693.8 cm?1. Raman and infrared data have been combined for estimation of several anharmonicity constants. The ν6 fundamental frequency is calculated as 347.0 cm?1. From the analysis of the ν2 Raman band, the following rotational constants of both the ground and upper states have been calculated: ; . 相似文献
3.
A red-degraded band head, normally badly overlapped by the gamma system, , of zirconium oxide, appears in emission spectra of zirconium arcs and in absorption spectra of S-type stars and of frozen rare gas matrices containing zirconium. The emission band has been examined at high-resolution with the aid of separated zirconium isotopes. Identification of the band as 0-0 of a system of zirconium oxide is confirmed by rotational analysis where the following constants (cm?1) are obtained for 90Zr16O: The Λ-type doubling in the 1Π state and the question of whether or is the true ground state of ZrO are discussed. 相似文献
4.
Akio Nakamura Shigeru Yamauchi Kazuo Fueki Takashi Mukaibo 《Journal of Physics and Chemistry of Solids》1978,39(11):1203-1206
The chemical diffusion coefficient in a single crystal of magnetite was measured by observing the relaxation of deviations from stoichiometry responding to a stepwise change in oxygen partial pressure between 1300 and 1450°C. The chemical diffusion coefficient was proportional to . The vacancy diffusion coefficient was calculated with the help of nonstoichiometric data and was found to be independent of the vacancy composition. The value of Dv was . 相似文献
5.
The self-diffusion coefficients of 14C in NbCx single crystals have been measured as a function of composition in the temperature range 1900–2315 K, and can be represented by the expressions The lower values of the activation energy and the pre-exponential term in NbC0.766 are attributed to a change in the path of C mass transport from that of an octahedral-tetrahedral-octahedral mechanism in NbC0.868 and NbC0.834 involving a C-metal divacancy mechanism. The effect of lattice geometry and the electronic charge distribution on the diffusion mechanism is also discussed. 相似文献
6.
The investigation of the emission infrared spectrum of P2 was performed with a high resolution Fourier spectrometer. Two new electronic systems were attributed to b3Πg → w3Δu and A1Πg → W1Δu transitions. The molecular parameters are obtained by a complete fitting procedure. The main equilibrium constants of the new states are (in cm?1): 相似文献
7.
The infrared spectrum of yttrium monoiodide has been excited in an electrodeless microwave discharge and explored between 2500 and 12 000cm?1 with a high-resolution Fourier transform spectrometer. A unique system is observed (ν00 = 9905.520 cm?1), which we attribute to a transition and an extensive analysis is made. Rovibrational constants are obtained for both states mainly from a simultaneous multiband fitting. This procedure is applied to the whole set of 2231 observed line wavenumbers in the 1-0, 0-0, and 0–1 bands, yielding a final weighted standard deviation of 0.0038 cm?1. Furthermore, a partial analysis of the 2-0 and 3-1 bands is performed. The following equilibrium constants are derived (cm?1): High-order constants Dv and Hv are also calculated for the various vibrational levels (v′ = 0, 1, 2, 3; v″ = 0, 1). 相似文献
8.
J.C.D. Brand U.D. Deshpande A.R. Hoy S.M. Jaywant E.J. Woods 《Journal of Molecular Spectroscopy》1983,99(2):339-347
Molecular constants of the first E 0+ ion-pair state of IBr vapor have been determined using polarization-labeling spectroscopy applied to the sequential transitions E 0+ ← B′ 0+ ← X 0+, while the second f 0+ ion-pair state is reported and characterized for the first time. A least-squares, simultaneous analysis of data for the I79Br and I81Br isotopes gives the following constants (in cm?1) for I79Br: , , . , . Preliminary data for the first ion-pair state, accessed in the sequence , indicate that Te is ?30 cm?1 higher in energy than that of the E state. 相似文献
9.
The 0-0, 1-1, 2-2, and 3-3 bands of the A2Π-X2Σ+ transition of the tritiated beryllium monohydride molecule have been observed at 5000 Å in emission using a beryllium hollow-cathode discharge in a He + T2 mixture. The rotational analysis of these bands yields the following principal molecular constants. From the pure electronic energy difference (EΠ - EΣ)BeT = 20 037.91 ± 1.5 cm?1 and the corresponding previously known values for BeH and BeD, the following electronic isotope shifts are derived and related to the theoretical approach given by Bunker to the problem of the breakdown of the Born-Oppenheimer approximation. 相似文献
10.
For free and interacting Hamiltonians, H0 and H = H0 + V(r) acting in L2(R3, dx) with V(r) a radial potential satisfying certain technical conditions, and for ? a real function on R with ?′ > 0 except on a discrete set, we prove that the Moller wave operators exist and are independent of ?. The scattering operator is shown to be unitary. Our proof utilizes time independent methods (eigenfunction expansions) and is effective in cases not previously analyzed, e.g. and many others. 相似文献
11.
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
12.
Electrical conductivity measurements on nickel oxide have been performed at high temperatures (1273 K<T< 1673 K) and in partial pressures of oxygen ranging from Po2 = 1.89 × 10?4 atm to Po2 = 1 atm. The dependence of the conductivity decreases from about for Po2 = 1 atm to smaller values for lower partial pressures of oxygen. The activation enthalpy for conduction increases for decreasing oxygen partial pressures (from 22.5 kcal mol?1 at Po2 = 1 atm to 26.0 kcal mol?1 for Po2 = 1.89 × 10?4 atm). This behaviour can be explained by the simultaneous presence of singly and doubly ionized nickel vacancies, with different energies of formation.Furthermore, chemical diffusion coefficient measurements have been performed in the same temperature range, using the conductivity technique, and leading to the result: . 相似文献
13.
Jan T. łopuszański 《Reports on Mathematical Physics》1976,9(3):301-307
It is shown that for spinorial charges Q(L))α (α = 1, 2, L = 1, …, S) satisfying the commutation relations where Q is a scalar charge commuting with the spinor charges as well aswith the energy- momentum vector Pμ, there can exist several different multiplets for free massive scalar and spinor fields. 相似文献
14.
K. Hoshino N.L. Peterson C.L. Wiley 《Journal of Physics and Chemistry of Solids》1985,46(12):1397-1411
The self-diffusion of 44Ti has been measured both parallel to and perpendicular to the c axis in rutile single crystals by a serial-sectioning technique as a function of temperature (1000–1500°C) and oxygen partial pressure (10?14 ? 1 atm). The oxygen-partial-pressure dependence of. D1Ti indicates that cation selfdiffusion occurs by an interstitial-type mechanism and that both trivalent and tetravalent interstitial titanium ions may contribute to cation self-diffusion. At po2 = 1.50 × 10?7 atm where impurity-induced defects are unimportant, and In the intrinsic region, the ratio D1Ti (⊥c)/D1Ti(∥c) was found to increase from 1.2 to 1.6 as the temperature decreased from 1500 to 1000°C. Computations based upon the defect model of Kofstad (involving the atomic defects Ti...iTi....iand V..o), of Marucco etal. (Ti....i and V..o), and of Blumenthal etal. (Ti...i and Ti....i) are compared with the experimental data on deviation from stoichiometry, electrical conductivity, cation self-diffusion and chemical diffusion in TiO2?x. These comparisons provide values of the defect concentrations, cation-defect diffusivities, electron mobility and reasonable values of the correlation factor for cation diffusion by the interstitialcy mechanism. Only the model of Kofstad is inconsistent with the data. 相似文献
15.
Lary W. Pinkley K. Narahari Rao M. Dang-Nhu G. Tarrago G. Poussigue 《Journal of Molecular Spectroscopy》1976,63(3):402-444
The ν3 fundamental vibration-rotation band of carbon-13 enriched methane (13CH4) was recorded using a high-resolution vacuum infrared grating spectrograph. Forbidden transitions of this band are reported for the first time. Of the nearly 900 transitions identified, 560 are forbidden transitions and 347 of the forbidden transitions have 11 ≤ J ≤ 18. Pairs of forbidden and allowed transitions having the same upper-state energy levels were used to calculate 550 independent differences between ground-state term values. From these data, a least-squares analysis was used to calculate the following values for ground-state structure constants and their standard deviations (in cm?1): , , , . The 550 values for the ground-state combination differences retained for analysis can be reproduced with an overall standard deviation of 0.0155 using the stated values for the structure constants. The note added in proof refines the above constants by including the newly observed microwave data. 相似文献
16.
H.D. Bist J.C.D. Brand A.R. Hoy V.T. Jones R.J. Pirkle 《Journal of Molecular Spectroscopy》1977,66(3):411-420
The band system of NO2, , has been measured in absorption in a neon matrix at 6 K, using 15NO2 and N18O2 in addition to the normal isotope. The spectrum consists essentially of a single, long progression of bands terminating on successive levels of the bending mode in the upper state. Transitions to odd- and even-v2′ states occur with a uniform intensity distribution indicating that the rotation of the bent ground state of NO2 about its near-prolate axis is hindered in the matrix. The observations strongly suggest that the top axis of the molecule coincides with a C2 axis of neon crystals in the polycrystalline matrix. Relative to the vapor absorption the matrix spectrum is red shifted by about 150 cm?1, the crystal field parameter V2 and principal constants of the state of 14N16O2 in neon being 相似文献
17.
The self-diffusion coefficient follows a relation of the form : D = (1,0?0.4+0.7)exp (?shape=case>34400RT±700) for b.c.c. europium D = (1,0?0.3+0.5) × 10?2 exp(? for β-b.c.c. gadolinium.Whereas europium has normal self-diffusion parameters, β-b.c.c. gadolinium must be set in the class of the anomalous b.c.c. rare-earth metals.From these results we conclude that there exists no evident connexion between the instability of the 4f shell and the activation energies anomalously low in the b.c.c. phases of the rare-earth metals. 相似文献
18.
A rotational analysis of the satellite bands of the β system of ZrO gives the splittings in the triplet states. For the lowest triplet state X′3Δ, these splittings are: 相似文献
19.
The decay kinetics and the yield of the π luminescence from the lowest triplet state of the self-trapped exciton have been studied in NaCl containing Li+ ions. It is found that the π luminescence band which is observed at 6K is replaced by a luminescence band peaked at 3.34 eV above 77K. The 3.34 eV luminescence band is ascribed to the recombination of the relaxed exciton trapped by a Li+ ion, (Vke)Li. The decay of the π luminescence induced by an electron pulse and the time change of the luminescence from (Vke)Li are explained in terms of the characteristic equation of the diffusion-limited reaction of the lowest triplet self-trapped excitons with the Li+ ions. From the analysis of the dependence of the decay rate of the π luminescence on temperature and on the Li+ concentration, we found the diffusion constant D of the lowest triplet self-trapped exciton in NaCl to be given by with and E0 = 0.13 eV. The present result can be regarded as the first clear experimental evidence for the hopping diffusion of the self-trapped exciton in alkali halides. The obtained values of Ea and D0 are discussed using the small polaron theory. The effect of the anharmonicity on the hopping of the self-trapped excitons is suggested to be significant. 相似文献
20.
The self-diffusion of 95Nb in single crystals of NbC0.868, NbC0.834 and NbC0.766 has been studied in the range of 2370–2660K. The diffusion coefficients are composition independent and can be described by the expression: An analysis of the results indicates that Nb diffuses by an (0-0) mechanism, just as a pure metal diffuses in a f.c.c. lattice, wherein the atom migrates from its lattice position directly to an analogous vacant site. As this process involves the energies of both migration and Nb vacancy formation, the slower diffusion rates of this species, relative to that of C whose mechanisms of transport involve only the energy of migration, are thus explained. 相似文献