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1.
A thickness dependence of the permittivity ofc-domain barium titanate single crystals was found. The experimental results were explained by means of a model of a dielectric with surface layers. The thickness of the layer and the permittivity of the surface layer and bulk of the crystal were determined.
iO3
iO3, -. . , .相似文献
2.
The decay of Re 186 was investigated with a double focusing spectrometer and scintillation spectrometer. Four transitions were observed with energies of 122·7±0·1 keV, 137·2 keV, 632·2±1·5 keV and 768·2±1·5 keV and the relative-ray intensities 18, 246, 0·9 and 1 respectively. TheK-conversion coefficients determined for low-energy transitions are in good agreement with the theoretical values (
K
122·7
=0·53±0·05,
K
137·2
=0·44±0·02). The relative intensities of theK, L, M andN conversion lines were also determined for these transitions:KL
I
+IIL
III
M=1·20±0·201·32±0·20 1±0·150·57±0·08 for 122·7 keV transition,KL
I
+IIL
III
MN=1·57±0·081· 72±0080·70±0·030·20±0·01 for 137·2 keV transition. In the beta spectrum two groups were observed with the end points of 1076±3 keV and 939±3 keV and relative intensities 74±4% and 21±4% respectively. For the branching ofK-capture it was found that 1·5% populates the 122·7 keV level and 3·5% the ground state. The decay scheme from the present results is proposed.The authors would like to thank M. Buriánek and V. Kopiva for help in the measurements. 相似文献
3.
V. N. Peregudov 《Hyperfine Interactions》1977,3(1):353-360
It is shown that interference effects in Mössbauer transmission experiments with pure E2 and mixed E2/M1 transitions are, generally, due to interference between the internal conversion and the photoeffect. This interference effect is mainly determined by the quadrupole part of the photoabsorption, which is comparable to the dipole part at transition energies of about 100 keV. A noticeable part of the interference effect in the case of E2 transitions can be attributed to the interference between the nuclear resonant scattering and Rayleigh scattering on atomic electrons. The angular distribution of the (, e) reaction cross section has been calculated for E2 transitions. 相似文献
4.
The saturation of a nonequidistant spin system is analyzed for the example of spin-5/2 nuclear quadrupole resonance in a molecular crystal; nonequilibrium states of the dipole-dipole reservoir are taken into account. The Zubarev method of a nonequilibrium statistical operator is used to derive equations generalizing the phenomenological balance equations for the populations in the case of a solid with strong magnetic dipole-dipole interactions. The real and imaginary parts of the dynamic susceptibility of the system, '-i, are found.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 41–45, May, 1974. 相似文献
5.
T. Ohtsubo Y. Nakayama T. Izumikawa S. Takeda N. Nakamura H. Tanji T. Minamisono 《Hyperfine Interactions》1994,88(1):25-33
Hyperfine interactions of12B(I
,T
1/2=21 ms) implanted in the substitutional site of B atoms (stable) in a (single crystal like) BN (hexagonal) was studied by use of a -NMR detection. For efficient and simple measurements, the conventional -NMR has been modified as a new nuclear quadrupole resonance technique (NNQR). For the present case with the nuclear spinI=1 the detection efficiency is improved about 30 times compared with the one with the old method. The quadrupole moment of12B was determined precisely as ¦Q(12B; 1+)¦=13.21±0.26 mb. 相似文献
6.
TDPAC measurements were carried out in Tungsten foils and single crystals using implanted181Hf as a probe nucleus. After proton irradiation at 25 K the trapping of a defect at the Hf probe was observed, which lead to a quadrupole interaction frequency of Q=354(5) MHz. The defect could be identified as a W self interstitial forming a 100 mixed dumbbell with a Hf impurity atom. 相似文献
7.
T. Minamisono T. Ohtsubo S. Fukuda I. Minami Y. Nakayama M. Fukuda K. Matsuta Y. Nojiri 《Hyperfine Interactions》1993,80(1-4):1315-1319
The -NMR technique has been modified in order to detect efficiently the nuclear quadrupole effects in the NMR spectra. -NMR is detected as a function of coupling frequency; all RFs that correspond to the coupling frequency were applied simultaneously. 相似文献
8.
A comprehensive quantum theoretical treatment of nuclear acoustic resonance (NAR) in metals is presented for the first time. Basic equations describing the NAR-absorption and NAR-dispersion are derived from the sound induced perturbation Hamiltonian Ih(t) by applying a generalized form of the Kubo susceptibility. It is shown that in metals, where a sound wave may induce nuclear magnetic dipole and nuclear electric quadrupole transitions simultaneously, the appearance of interference terms enables one to determine not only the absolute values but also the signs of the gradient-elastic tensor components. Explicit expressions are displayed for the dipolar, quadrupolar and interference contributions to the generalized NAR susceptibility in cubic metals. As an example the derivative of the expected93Nb NAR-absorption line (|m|=1) is calculated for different signs of the gradient elastic tensor componentS
44. 相似文献
9.
J. L. Bell 《Foundations of Physics》1985,15(12):1179-1202
In this paper we construct the ortholattices arising in quantum logic starting from the phenomenologically plausible idea of a collection of ensembles subject to passing or failing various tests. A collection of ensembles forms a certain kind of preordered set with extra structure called anorthospace; we show that complete ortholattices arise as canonical completions of orthospaces in much the same way as arbitrary complete lattices arise as canonical completions of partially ordered sets. We also show that the canonical completion of an orthospace of ensembles is naturally identifiable as the complete lattice of properties of the ensembles, thereby revealing exactlywhy ortholattices arise in the analysis of tests or experimental propositions. Finally, we axiomatize the hitherto implicit concept of test and show how they may be correlated with properties of ensembles. 相似文献
10.
J. A. Koch R. W. Lee J. Nilsen J. C. Moreno B. J. MacGowan L. B. Da Silva 《Applied physics. B, Lasers and optics》1994,58(1):7-11
We point out that existing Ne-like X-ray lasers have sufficient brightness to be used as pump sources in resonant pump-fluorescence experiments, and we discuss some of the potential benefits and limitations of such experiments. In preliminary experiments, we have measured the line overlap of the Ne-like yttrium X-ray laser near 155 with 4f–3d transitions in H-like Na and He-like Mg. These experiments used a high-resolution grating spectrometer, and calibrated the wavelength of the yttrium laser by comparison against lines of known wavelength. The results indicate that the wavelength of the yttrium laser is 154.985 ± 0.025 , a factor of 2–4 improvement in precision over previous calibrations. We find that the yttrium laser is 100 m to the long-wavelength side of both the He-like Mg line and the H-like Na line, so that neither resonance is perfect; however, Stark broadening could improve the overlap in the latter scheme, and bulk Doppler shifting could improve both resonances. We also find a good resonance between the yttrium laser and an un-identified transition which we tentatively attribute to copper. 相似文献
11.
Vladimir Chechersky 《Hyperfine Interactions》1994,93(1):1711-1716
57Fe Mössbauer effect measurements as a function of temperature between 78 and 293 K in grain-aligned YBaCuO (T
c=89 K, T
c<2 K) with bothc andc orientations revealed a sequence of anomalies in the recoilless fraction, center shift and linewidth of all57Fe quadrupole doublets in the host lattice. These anomalies are believed to arise due to antiferroelectric phase transitions driven by a nonlinear anharmonic vibrational motion of oxygen atoms in a breathing mode configuration. The results obtained are indicative of a possible coexistence of high-T
c superconductivity and antiferroelectricity in 1-2-3 ceramics. 相似文献
12.
M. Ionescu-Bujor A. Iordachescu E. A. Ivanov D. Plostinaru G. Pascovici 《Hyperfine Interactions》1981,11(1):171-175
The radiation damage effects on the electric quadrupole interaction (QI) for the system SnCd were investigated with the time-differential perturbed angular distribution (TDPAD) method and three nuclear reaction recoil Sn probes, in the temperature range from 80 to 590 K. The obtained results are consistent with a static defect QI strength distribution (10%) around a mean value comparable with the unique QI strength corresponding to the undistorted crystal lattice. 相似文献
13.
Interface delocalization or depinning transitions such as wetting or surface induced disorder are considered. At these transitions, the correlation length for transverse correlations parallel to the surface diverges. These correlations are studied in the framework of Landau theory. It is shown the t–1/2 at all types of transitions for systems with short-range forces wheret measures the distance from bulk coexistence. 相似文献
14.
The two-frequency nuclear quadrupole resonance method is used to determine the relaxation time for all single-quantum transitions in a quadrupole spin system with many energy levels from the results obtained for a single transition, which is impossible in a one-frequency method. The accuracy is the same as in the measurement of relaxation time in the case of one-frequency pumping of the transition chosen as the “basis.” The results of measurements are presented and determination of relaxation constants for KReO4 and NaReO4 as well as SbCl3 and SbBr3 and their complexes at various temperatures with the help of the two-frequency NQR method. 相似文献
15.
We report a study of the impurity-radiation damage interaction for In in silver. Time-differential perturbed angular correlation experiments were carried out on111Cd, the radioactive daughter of111In produced and recoiled in Ag following the109Ag(, 2n)111In nuclear reaction. All irradiations were performed at 80 K. The dose-rate and annealing temperature dependences of the defect-induced quadrupole interaction on111Cd were investigated. Clear differences are observed between the effects of correlated damage (the impurity interacting with the damage created by its own recoil) and uncorrelated damage (where the impurity is submitted to the influence of other damage cascades). In the former case (low dose-rate experiments), about 6% of the111In impurities are subject to a well-defined quadrupole interaction which is ascribed to a near-neighbor vacancy. This proportion is temperature-independent up to 500 K, but the amplitude of the quadrupole frequency is reduced by a factor of three between 300 and 400 K. Assuming vacancy release by the impurity, this would lead to a binding energy of 0.34(15) eV. The remainder of the111In nuclei are subject to a distribution of quadrupole interactions presumably due to a statistical repartition of lattice defects at some distance from the impurities. The width of the distribution changes upon annealing: a clear transition takes place at 200 K, which is the divacancy mobility threshold in Ag deduced from resistivity experiments. When cascade overlap occurs (high dose-rate experiments), no impurity-defect trapping is evidenced but a distribution of quadrupole interactions due to surrounding damage is still found. From these experiments, an order of magnitude of the damage cascade size is deduced. Our results are discussed in terms of available information on the impurity-damage interaction in various hosts; a compilation of all results on the impurity-vacancy interaction known to us is also presented in the paper.This work is part of a Ph.D. Thesis submitted by L. Thomé to Université Paris-Sud. 相似文献
16.
T. Ohtsubo M. Tanigaki S. Fukuda Y. Nakayama S. Takeda N. Nakamura H. Tanji M. Fukuda K. Matsuta Y. Nojiri T. Minamisono 《Hyperfine Interactions》1993,78(1-4):185-190
Hyperfine interactions of12B(I
=1+,T
1/2=21 ms) implanted in the substitutional site of B in BN (hexagonal) was studied by detecting -NMR. In order to measure the quadrupole coupling constant efficiently, we employed a newly developed quadrupole resonance technique (NNQR). The quadrupole moment of12B was determined to be |Q(12B)|=13.21±0.26 mb. 相似文献
17.
D. Dubbers H. Ackermann M. Grupp P. Heitjans H. -J. Stöckmann 《Zeitschrift für Physik B Condensed Matter》1976,25(4):363-368
An experimental method is presented which allows the determination of the sign of nuclear electric quadrupole interactions in solids. Activated target nuclei with a purely dipolar spin polarization are produced by capture of polarized thermal neutrons. The quadrupole coupling of the nuclei to the electric field gradient tensor in the target crystal converts this (dipolar) polarization partly into a (quadrupolar) alignment, which can be measured by the anisotropy of the-ray emission in a succeeding nuclear transition. The sign of the alignment created in this reorientation process depends on the sign of the electric quadrupole interaction. The reorientation effect can be enhanced by selective induction of nuclear magnetic resonance transitions. The method has been applied to measure the sign of the crystal electric field gradient (efg) in tetragonal MgF2. Further, the sign of an efg in cubic CaF2 originating from a19F interstitial adjacent to the activated20F probe nucleus has been determined. The method is in principle applicable to a considerable number of nuclides. 相似文献
18.
We report on a test of the isotropy of light propagation performed by comparing the resonance frequencies of two orthogonal cryogenic optical resonators subject to Earths rotation over 1yr. The technical aspects of the experiment are discussed and the analysis of the data is presented in detail. For a possible anisotropy of the speed of light c, we obtain c/c0=(2.6±1.7)×10-15. Within the general extension of the standard model of particle physics, we extract limits on seven parameters at accuracies down to 10-15, improving the best previous result by about two orders of magnitude. Within the Robertson–Mansouri–Sexl test theory, this implies an isotropy-violation parameter --1/2=(2.2±1.5)×10-9, about three times lower than the best previous result. PACS 03.30.+p; 12.60.-i; 06.30.Ft 相似文献
19.
We determined the199mHg nuclear quadrupole interaction in the misfit or superstoichiometric compound Hg
x
TiS2 by time differential perturbed angular correlation. A unique Hg-site withv
Q
=511(1) MHz and =0.410(4) was observed, irrespective of the Hg-uptake (2/3x4/3). We propose a model of Hg-Hg zig-zag chains which accounts for these observations as well as for the X-ray diffraction data. 相似文献
20.
The pure rotational spectrum of CHF2I has been recorded for the first time, in a supersonic expansion in the region 1.7-17 GHz, and at room-temperature in the region 302-318 GHz. The observed transitions span the values of J″ from 0 up to 67. Precise rotational and centrifugal distortion constants have been determined. Furthermore, the complete iodine nuclear electric quadrupole coupling tensor, in the inertial and principal axes, has been determined. Quantum chemical calculations have been performed to aid with the analysis. Iodine quadrupole mediated perturbations have resulted in the following observations: (i) several transitions having enhanced intensities and (ii) the observation of several forbidden, ΔJ=±2, transitions. Comparisons in electronic structure are made between the series of molecules CH3-nFnX; and X = Cl, Br, I. 相似文献