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1.
Measurements of sodium tracer diffusion (Dt) and ionic conductivity (σ) have been made on the same single crystals of sodium beta-alumina of composition 1.23 Na20.11 Al2O3. The σ- measurements were made over the temperature 390–660 K using reversible (liquid sodium) electrodes. A fit to the conductivity data gives . The Dt, measurements employed two techniques, i.e. nondestructive profiling over the temperature range 210–750 K and cation exchange over the temperature range 505–970 K. The results of the two techniques were in close agreement and can be expressed as for T>520K and . The “transition” region between 470 and 520 K is not observed in the conductivity measurements. Silver cation exchange was used to determine the number of mobile sodium ions. A comparison of Dt and σ data yielded a Haven ratio that is temperature dependent, ranging in value from 0.45 at 870 K to 0.35 at 370 K. 相似文献
2.
J.F. Seely R.H. Dixon R.C. Elton J.G. Lunney 《Journal of Quantitative Spectroscopy & Radiative Transfer》1982,27(3):297-306
The Lyman-α and adjacent dielectronic satellite lines have been observed in the spectra from laser-irradiated solid targets. In a carbon plasma from a planar target, the relative intensity of the satellite line of C(V) increases as a function of electron density in the range 8 × 1019 to 2 × 1020 cm?3. As analysis of a series of imploded microballoon experiments indicates that the and satellite radiation of Si(XIII) increases for electron densities 1 × 1022?2 × 1023 cm?3. The satellite intensity distributions have been numerically simulated using a rate equation model. It is shown that the carbon and silicon satellite data may be interpreted in a consistent manner, and the extension to higher atomic numbers Z and higher electron densities is considered. 相似文献
3.
H. Venghaus 《Journal of luminescence》1978,16(3):331-341
Luminescence measurements were performed on high purity epitaxial n-GaAs for various excitation intensities I0 in the range . The luminescence line corresponding to the radiative decay of the shallow donor bound exciton, (D0, X), broadens with increasing I0 and appears as a doublet for , while the two-electron replica of the (D0, X) remains a single narrow line. The doublet structure of the (D0, X) at elevated excitation levels is due to missing luminescence intensity in the center of the line as a consequence of low (D0, X) concentration in a layer extending 1–2 μm from the sample surface into the bulk. The low concentration of (D0, X) is attributed to capture of (D0, X) quanta into surface states, extending to lower energies from the Fermi level fixed by the shallow donors. Comparison of the present results with luminescence spectra obtained by various authors reveals, that unexplained spectral features in the (D0, X) region of n-GaAs reported in the literature are a consequence of high excitation intensity and correspond to the effect reported here. In partly compensated p-GaAs with donor concentrations as given above, the (D0, X) did not transform into a doublet structure even at excitation intensity. 相似文献
4.
The rotational motion of the OH? ion was studied in cubic NaOH at 575 K with quasielastic incoherent neutron scattering. The data are compared to two simple models yielding values for the radius of rotation R, the translational mean square displacement 〈u2〉H, the rotational jump rate τ?1 and the rotational diffusion coefficient DR. The following parameter values are obtained: (a) rotational jump model: , , (b) rotational diffusion model: . 相似文献
5.
Experimental data concerning the electrical conduction and Hall coefficient in HgTe samples with acceptor states have been collected and analysed. In the analysis three ranges of acceptor concentration have been distinguished: a low concentration range up to about 5 × 1015 cm?3 (pure samples), a high concentration range from 1016 to 1018 cm?3 (p-like samples), and an extremely high concentration range above 1018 cm?3 (p-type samples). In pure HgTe samples the holes are in the valence band, in p-like samples the “holes” are in the impurity band, and in p-type HgTe samples the holes are in a strong mixing impurity-valence band. The mobility of holes in the valence band is of the order of . The mobility of “holes” in the impurity band decreases with increasing impurity concentration from about to . The mobility of holes in p-type HgTe samples is independent of the acceptor concentration and is equal to . 相似文献
6.
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
7.
Compound nucleus states in and have been investigated with the and three-particle reactions. The observed states (EX≈20 MeV) can be understood, in analogy to the ground states of the A=5 system, by coupling a nucleon to the first 0+ excited state of . 相似文献
8.
D. Chultem V.S. Evseev V.M. Sidorov V.A. Khalkin R. Engfer H.H. Müller H.K. Walter 《Nuclear Physics A》1979,316(3):290-294
A search for the existence of the tetraneutron has been made using the double charge exchange reaction residuals for 4n production and the capture process in the same target, , for the 4n detection. No event has been found, giving an upper limit for the product of the production cross section σp, the detection cross section σd and the 4n lifetime τ. Assuming 10?18 ≦ τ ≦ 10?9 sec it follows that σpσdτ ≦ 2.5 × 10?65cm4 sec with 90 % confidence, and for with 90 % confidence. The magnitude of this value is comparable to the experimental limit of the 4He(π?, π+)4n cross section. 相似文献
9.
B. Yaakobi T. Boehly P. Bourke Y. Conturie R.S. Craxton J. Delettrez J.M. Forsyth R.D. Frankel L.M. Goldman R.L. McCrory M.C. Richardson W. Seka D. Shvarts J.M. Soures 《Optics Communications》1981,39(3):175-179
Thermal conduction, mass ablation rate, pressure and preheat were investigated in the interaction of a frequency tripled Nd: glass laser of power 0.-0.2 TW with flat targets. In the range for 400 ps pulses we find: (a) thermal conduction may be described by a flux limiter f = 0.04 ± 0.01; (b) the mass abaltion rate depends on the incident laser irradiance as ; (c) the pressure near the ablation surface increases approximately linearly with irradiance and is about 70 Mbar at 1015 W/cm2, and (d) preheat as evidenced by Kα X-ray line emission is significantly lower than in λ = 1.05 μm irradiation. 相似文献
10.
Gamma-ray angular distributions, nγ angular correlations, γγ coincidences and Doppler-shift attenuations have been measured in the 42Ca(α, nγ)45Ti reaction. In addition to the known positive-parity levels forming the band members are identified in 45Ti. They are the levels at 1565 keV, 1958 keV, 2258 Reduced transition probabilities are obtained for the γ-decays of these levels as well as for those of the band members. The excitation energies and transition probabilities are well reproduced by a rotation-particle-coupling model calculation with deformation parameter β = 0.30–0.35. 相似文献
11.
A. Goldman S.C. Schmidt 《Journal of Quantitative Spectroscopy & Radiative Transfer》1975,15(2):127-138
Individual spectral line parameters for the Δν=1 transitions of the nitric oxide molecule have been generated for both atmospheric and elevated temperatures. The line parameters compilation includes the , the and the satellite bands for the 14N16O, 15N16O, 14N18O and 14N 17O isotopes. Lambda-type splitting has also been included. Line by line spectral absorptance calculations utilizing the calculated line parameters have been compared with experimental quantitative absorption spectra of NO at 800 K. Effects of line splitting on line by line synthetic spectra are discussed. 相似文献
12.
Lifetimes of low-lying states in 19F were measured using the Doppler-shift attenuation method through the 15N(α, γ)19F reaction. Values of τm = 3700 ± 700 fs (1.35 MeV), 140 ± 15 (1.46), 19 ± 7 (4.00) and 63 ± 19 (4.03) were obtained for the lowest , , and members, respectively, of the rotational band and 5 ± 3 fs (1.55 MeV) and 370 ± 25 (2.78) for the and members of the ground-state band. For the Doppler-shift attenuation analysis correction factors of the nuclear and electronic stopping powers were determined by measuring the Doppler-shift attenuation and γ-ray line shape of the 2.78 → 0.20 MeV transition and range values of 100, 200. 300 and 370 keV 19F nuclei in tantalum. All calculations were done with Monte Carlo methods. The transition strengths are discussed in terms of different theoretical predictions. 相似文献
13.
R. Kroth S.K. Bhattacherjee C. Günther M. Guttormsen K. Hardt H. Hübel A. Kleinrahm 《Physics letters. [Part B]》1980,97(2):197-199
The g-factors of the 10+ isomeric states in 194Hg and 196Hg have been measured using the in beam IPAD method. The results and are in agreement with the value expected for an (?2) neutron satructure and clearly contradict the previous assignment as () proton configurations. Cranking model calculations show that the neutron excitation energies in the rotating frame agree satisfactorily with the experimental energies and that the proton excitations are expected ≈2 MeV above the experimental yrast line 相似文献
14.
W. Klamra K. Fransson B. Sundström M. Brenner S. Engman R. KvarnströM 《Nuclear Physics A》1982,376(3):463-477
The energy level structure of 101Ru was studied using the reactions 100Mo(α, 3n)101Ru and 100Mo(3He, 2n)101Ru. Excitation functions, γγ coincidences and γ-ray angular distributions were measured. Three ΔI = 2 cascades proceeding to a , and state were observed. A decay scheme is presented showing energies up to 5849 keV and spins up to . The bands are discussed within the framework of the Nilsson model with Coriolis coupling in which the recoil effect has been properly introduced. 相似文献
15.
P.M. Heinen J.J. Engelen E.W. Kittel W.J. Metzger M.M. Schouten J.S.M. Vergeest R.T. Van De Walle B. Jongejans H. Voorthuis M. Cerrada R.J. Hemingway S.O. Holmgren M.J. Losty 《Nuclear Physics B》1977,122(3):443-463
A partial-wave analysis of the low-mass (π+π?p) system produced in the reaction K?p → K?(π+π?p) at 4.2 GeV/c incident momentum is performed in order to study the two (π+π?p) enhancements around 1500 and 1700 MeV. It is found that the low-mass (π+π?p) system can be described using the spin-parity states and only. In the 1500 MeV region contributions are observed from the wave decaying into p? and the wave decaying into Δ++π?; in the 1700 MeV region contributions are found from the wave decaying into Δ++π?, the wave decaying into p?, and the wave decaying into p?. 相似文献
16.
Paul S. Julienne 《Journal of Molecular Spectroscopy》1976,63(1):60-79
The role of spin-orbit mixing in the O2 Schumann-Runge predissociation is investigated. The state is found to cross the state near 2.0 Å with an interaction matrix element of approximately 55 cm?1. This state contributes to the widths of the Bv ≥ 6 levels, but introduces only small level shift perturbations. When the partial widths due to the interaction are added to the previously calculated widths due to the 5Πu, 3Πu, and 1Πu states, reasonable agreement is obtained with experimental measurements on O16O16 and O18O18. The possibility of non-Lorentzian line profiles and the dependence of the width on rotational quantum number is investigated. The approximation of the spin-orbit matrix element by its value at the crossing point is shown to be a good approximation for calculating the second difference perturbations. 相似文献
17.
Levels of the N = 81 nucleus 145Gd have been investigated by in-beam γ-ray and conversion electron spectroscopy with the 144Sm(3He, 2n) reaction. Fourteen new low- and medium-spin states between 1.0 and 2.4 MeV excitation, the known yrast levels up to spin , five other high-spin non-yrast states and a new 20.4 ns isomer at 2200.2 keV in 145Gd have been observed. The isomer decays via a fast 927.3 keV E3 transition with B(E3) = 48 ± 7 W.u. Another weaker decay branch is a mixed, strongly hindered E1 + M2 + E3 transition to the state. We propose an octupole main configuration for the isomer, analogous to the 997 keV isomer in 147Gd. The levels of 145Gd are discussed on the basis of the spherical shell model. 相似文献
18.
G. Tarrago M. Dang-Nhu G. Poussigue G. Guelachvili C. Amiot 《Journal of Molecular Spectroscopy》1975,57(2):246-263
High resolution spectra of the ν3 band of methane, 12CH4, were recorded by using a “third generation vacuum Fourier interferometer”; a large pressure range (from 0.009 to 10 Torr) with a sample path fixed at eight meters was used, enabling observation of transitions with intensity ratios as low as . More than 350 forbidden transitions of the ν3 band, including about 125 transitions of the Q+ branch, were unambiguously identified. Of the 277 transitions retained for computations, one-hundred have 11 ≤ J ≤ 16. From combination difference relations using pairs of transitions having the same upper state energy level (forbidden-allowed and forbidden-forbidden pairs were used), 276 independent differences between ground state energy levels could be determined with uncertainties of about 0.001 cm?1.These data yielded the following values for the ground state structure constants of 12CH4 along with their standard deviations (in cm?1): , , , , , , Thus, for the first time, the scalar constant π0 has been evaluated and ir values have been obtained for the two tetrahedral constants ?0 and ξ0; furthermore, these values are in very good agreement with the ones recently determined from radiofrequency data, i.e., in cm?1: , , From these values, the 276 differences can be reproduced with an overall rms deviation equal to 0.0009 cm?1.Finally, the ground state energies of 12CH4 have been calculated for J ≤ 16. 相似文献
19.
H.H. Eggenhuisen L.P. Ekström G.A.P. Engelbertink H.J.M. Aarts W.G.J. Langeveld 《Nuclear Physics A》1978,299(1):175-188
Yrast states of 41K and 41Ca have been investigated with the 26Mg(18O, p2nγ)41K and 26Mg(18O, 3nγ)41Ca reactions at a beam energy of 34 MeV. Gamma-gamma coincidence, γ-ray angular distribution and linear polarization measurements were performed with a Ge(Li)-NaI(Tl) Compton suppression spectrometer and a three-crystal Ge(Li) Compton polarimeter. Unambiguous spin-parity assignments of , , , , and to the 41K levels at Ex = 1.68, 2.53, 2.76, 2.77, 4.27 and 4.98 MeV and of to the 41Ca levels at Ex = 3.20, 3.37 and 3.83 MeV, respectively, have been obtained. Excitation energies, branching ratios, multipole mixing ratios and transition strengths are reported. The main features of the 41K and 41Ca level and decay schemes are reproduced in a 2p-1h and 3p-2h shell-model calculation. 相似文献
20.
Rotational bands up to high-spin members in odd-neutron Hf nucleides are studied by in-beam spectroscopy using (α, xn) reactions on isotopically enriched Yb targets. The [521], [512], and the mixed positive-parity (mainly [633]) bands were observed in 173Hf and 175Hf while the [514], (mainly [624]), and the +) bands were studied in 177Hf. The analysis of the band structure within the Nilsson model is extended to also include adjacent odd Hf nuclei making it possible to follow these bands through five isotopes of Hf. 相似文献