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1.
A realistic calculation of the viscosity coefficients for 236U from ground equilibrium shape to saddle point is presented based on the linear response theory, in which the single particle spectra and wave function are provided by generalized Nilsson model. The dependence of viscosity coefficients γδ2δ2, γδ3δ3, γδ4δ4, γδ2δ3, γδ2δ4, γδ3δ4, on the collective variables δ2, δ3, δ4 is studied at various values of the nuclear temperature with the smearing width Γ=0.1hω0.  相似文献   

2.
The temperature dependence of magnetization of the R3Co11B4 compounds has been analysed using the two-sublattice molecular field theory. The molecular field coefficients, nCoCo, nRCo, nRR, have been calculated by a numerical fitting process. The analytic form of the exchange field HR(T) varying with temperature for each of the R3Co11B4 compounds is presented, and some results are discussed.  相似文献   

3.
Taking the relative distanceR and the deformationδ of each nucleus as the collective variables, we solve the two dimensional coupled dynamical equations of motion with friction in the framework of the linear response theory. In solving the equations of motion, we approximately replace the inertia tensor with the hydrodynamical one and use the modified liquid-drop one as the collective potential energy. As the frictional coefficients we use the microscopically calculated ones in the previous paper. The calculation is done for the reaction of28Si+20Ne, in which the incident energy of20Ne is 120 MeV. Results show that our microscopically calculated friction gives the large value of energy dissipation which amounts to the “completely damped” collision. Besides it, growths of the oblate deformation in the entrance channel and the prolate deformation in the exit channel are clearly seen. They give a large influence on the time development of the energy dissipation. We compare our calculated results with the experimental data for the reactions of 120 MeV20Ne with27Al. The agreement between them is found to be reasonably good.  相似文献   

4.
The temperature dependence of magnetization is analysed for R2Fe17C via the two-sublattice molecular field theory. The molecular field coefficients nFF, nRF and nRR are obtained, by which TC was calculated. Using the least-squares method, the fitted-form of HR(T) varying with temperature for each compound is presented. The results are analysed. In addition, the parameters F=MFe2(0)nFF/TC was calculated for each R2Fe17C. By F, some phenomena different from the normal view were explained.  相似文献   

5.
The linear and nonlinear optical properties in a spherical nanolayer quantum system subjected to an uniform applied electric field directed with respect to the z-axis have been theoretically investigated within the compact-density matrix formalism and the iterative method. The dependence of the optical absorption coefficients (ACs) and refractive index (RI) changes on the core radius R1, on the inner radius of the clad R2, and on the applied electric field F has been investigated detailedly. The results show that the optical ACs and RI changes of the nanospherical layer have been strongly affected by these factors. Moreover, the outcome of the calculation also suggests that all the factors mentioned above can give rise to blue-shift or red-shift significantly.  相似文献   

6.
The effect of anions such as Cl, SO42−, and HPO42− on the phase stability of FeOOH (α or γ) during precipitation is investigated. Oxidation of Fe(OH)2·xH2O from FeCl2 solution with high Cl concentration ([Cl]/[Fe]=RCl≥8) or (NH4)2Fe(SO4)2 (FAS) with [HPO42−]/[Fe]=RP≥0.02 yields phase-pure γ-FeOOH. In the medium ranges of RCl and RP, mixed phases of α-FeOOH and γ-FeOOH are obtained. Replacement of OH by Cl with the bridging cations or strongly bonded HPO42− ions in the matrix of the intermediate phase (Fex2+Fey3+(OH)2x+2ynz·xH2O(A)zn, where A is anions such as Cl, SO42−, HPO42−, etc.), promoted the lower density γ-FeOOH. However, the particles are less developed and have poor crystallinity as evidenced from transmission electron microscope and thermogravimetry-differential thermal analysis of the precipitates. Whereas, monophasic, uniformly sized, nano-lath shaped particles with high aspect ratio >10 are obtained when morphology-controlling cation additives such as Pt4+, Pd2+ or Rh3+ are present in FeCl2 (RCl≥8) solution. Preferential adsorption of additives on (0k0) and (h00) planes limits the growth in the perpendicular directions leading to high aspect ratios. The effect of these additives are suppressed by the phosphate ion, a strong complexing ligand, giving rise to fibrous aggregate with the length of individual particles as small as 10-30 nm. While most of the Cl ion is removed from the final precipitates on washing, phosphate remained as HPO42− as evidenced from IR absorption spectra. Maghemite obtained by dehydroxylating γ-FeOOH contains randomly distributed micropores bringing in the relaxation effects of spins on the surface atoms as deciphered from Mössbauer spectroscopy. This leads to the low σs (44-48 emu/g) and Hc (120-130 Oe) for γ-Fe2O3−δ particles. Whereas nearly pore-free single crystalline particles obtained by reduction followed by reoxidation has high value of σs (73 emu/g) and Hc (320 Oe), which decreases to 30 emu/g and 75 Oe, respectively, for nanoparticles obtained from phosphate stabilized lepidocrocite. The mobility of iron ions and counter mobility of vacancies during the topotactic transformation of γ-FeOOH to magnetite to γ-Fe2O3−δ renders the particles pore-free.  相似文献   

7.
N2-broadening coefficients are measured for 61 transitions of PH3 in the QR branch of the ν2 band and the PP, RP, SP, and PQ branches of the ν4 band, using a tunable diode-laser spectrometer. The recorded lines with J values ranging from 1 to 16 and K from 0 to 11 are located between 1008 and 1106 cm−1. The collisional widths are determined by fitting each spectral line with a Voigt profile, a Rautian profile, and a speed-dependent Rautian profile. The latter models provide larger broadening coefficients than the Voigt model. These coefficients have also been calculated on the basis of a semiclassical model of interacting linear molecules by considering an atom-atom Lennard-Jones potential in addition to the electrostatic contributions. The theoretical results are in good agreement with the experimental data and reproduce the J dependence of the broadenings, but their decrease at high J values is overestimated for the QR (JK) transitions.  相似文献   

8.
The parameters proposed by W. D. Myers to describe the radial shape dependence of the nuclear surface are shown to be as useful as they are natural. For spherical nuclei, the central radiusC, the charge radiusR, the quadratic radiusQ are redefined, and it is shown how they are interrelated by Myers' surface widthb, flair γ3, crookedness γ4, and the higher shape parameter γ5. All these quantities are calculated for some special charge distribution functions. (For symmetric distributions, possessing a symmetry center atC, the odd surface momentsb 3γ3 andb 5γ5 vanish.) The connection of the surface moments Гμ =b μ γ μ with the volume momentsF k that have been extracted by K. W. Ford and J. G. Wills from muonic atoms, is indicated.  相似文献   

9.
N2-broadening coefficients have been measured for 41 transitions of PH3 at −100 °C in the QR branch of the ν2 band and the PP, RP, and SP branches of the ν4 band, using a tunable diode-laser spectrometer. The recorded lines with J values ranging from 1 to 13 and K from 0 to 10 are located between 1026 and 1093 cm−1. The collisional widths are determined by fitting each spectral line with a Voigt profile, a Rautian profile, and a speed-dependent Rautian profile. The latter models provide larger broadening coefficients than the Voigt model. These coefficients have also been calculated on the basis of a semiclassical model of interacting linear molecules by considering an atom-atom Lennard-Jones potential in addition to the electrostatic contributions. By comparing broadening coefficients at room and low temperatures, the temperature dependence of these broadenings has been determined both experimentally and theoretically.  相似文献   

10.
This study compared three methods for analyzing DCE-MRI data with a reference region (RR) model: a linear least-square fitting with numerical analysis (LLSQ-N), a nonlinear least-square fitting with numerical analysis (NLSQ-N), and an analytical analysis (NLSQ-A). The accuracy and precision of estimating the pharmacokinetic parameter ratios KR and VR, where KR is defined as a ratio between the two volume transfer constants, Ktrans,TOI and Ktrans,RR, and VR is the ratio between the two extracellular extravascular volumes, ve,TOI and ve,RR, were assessed using simulations under various signal-to-noise ratios (SNRs) and temporal resolutions (4, 6, 30, and 60 s). When no noise was added, the simulations showed that the mean percent error (MPE) for the estimated KR and VR using the LLSQ-N and NLSQ-N methods ranged from 1.2% to 31.6% with various temporal resolutions while the NLSQ-A method maintained a very high accuracy (< 1.0×10− 4 %) regardless of the temporal resolution. The simulation also indicated that the LLSQ-N and NLSQ-N methods appear to underestimate the parameter ratios more than the NLSQ-A method. In addition, seven in vivo DCE-MRI datasets from spontaneously occurring canine brain tumors were analyzed with each method. Results for the in vivo study showed that KR (ranging from 0.63 to 3.11) and VR (ranging from 2.82 to 19.16) for the NLSQ-A method were both higher than results for the other two methods (KR ranging from 0.01 to 1.29 and VR ranging from 1.48 to 19.59). A temporal downsampling experiment showed that the averaged percent error for the NLSQ-A method (8.45%) was lower than the other two methods (22.97% for LLSQ-N and 65.02% for NLSQ-N) for KR, and the averaged percent error for the NLSQ-A method (6.33%) was lower than the other two methods (6.57% for LLSQ-N and 13.66% for NLSQ-N) for VR. Using simulations, we showed that the NLSQ-A method can estimate the ratios of pharmacokinetic parameters more accurately and precisely than the NLSQ-N and LLSQ-N methods over various SNRs and temporal resolutions. All simulations were validated with in vivo DCE MRI data.  相似文献   

11.
The response of reflectometric and ellipsometric parameters to small changes in the properties of the metal-solution interphase is analysed by the use of linear approximation expressions. It is shown that the changes in R6 and R are generally closely related, and the ratio (δR/RR/R may be insensitive to the value of n?film. On the other hand, the ratio δΔ/(δR/R)6 is shown to have always good sensitivity to n?film. For two surface processes on solid electrodes, gold surface oxidation and hydrogen adsorption on platinum, it is demonstrated that the information extracted from the combined measurements of Δ and R transients is more detailed and informative compared with the evidence obtained by reflectometry alone. A fast component is resolved in the process of gold surface oxidation, and shown to result optically in an apparent metallic film, which probably reflects changes in the properties and structure of the metal surface atoms induced as the oxygen uptake commences.  相似文献   

12.
The absorption spectra of KCl single crystals irradiated with electrons and protons at energies of 15 and 100 keV and a particle flux ranging from 5×1012 to 1015 cm?2 are investigated. The absorption bands attributed to simple (F, F a, K) and complex (M, R 2, R 4, N) color centers are identified in the spectra. The correlation dependences of the absorption coefficients for M, R 2, and R 4 centers on the absorption coefficient of F centers and the correlation dependences of the absorption coefficients for R 2 and R 4 centers on the absorption coefficient of M centers are established. The oscillator strengths are calculated for M, R 2, and R 4 color centers.  相似文献   

13.
Line positions, intensities, Lorentz self- and N2-broadened half-width coefficients have been measured for PQ3, PQ2, PQ1, RQ0, RQ1, RQ2, and RQ3 sub-band transitions in the ν9 fundamental band of 12C2H6. A multispectrum nonlinear least-squares fitting technique was used to fit up to 17 high-resolution (∼0.00156 cm−1), room temperature absorption spectra of pure (99.99% chemical purity) natural sample of ethane and lean mixtures of the high-purity ethane diluted with N2. A Bruker IFS 120HR Fourier transform spectrometer located at the Pacific Northwest National Laboratory (PNNL), in Richland, Washington was used to record the data. A standard Voigt line shape was assumed to fit all the data since no line mixing or other non Voigt line shapes were required to fit any of the spectra used in the analysis. Short spectral intervals (∼2-2.5 cm−1) of all 17 spectra covering a specific PQ or RQ sub-band were fit simultaneously. For the first time in an ethane band, pressure-broadened half-width coefficients were determined for the torsional-split components. However, for better reliability of the retrieved coefficients for the weaker components (transitions with large intensity ratios of 4:1 or 3:1 for most K levels between the strong and weak components), constraints were used such that the half-width coefficients of both torsional-split components for a given J were identical for a specific broadening gas. No pressure-induced shift coefficients were necessary to fit the spectra to their noise level. The present study revealed for the first time the dependence of self- and N2-broadened half-width coefficients upon the J, K quantum numbers of the transitions in ethane. A number of transitions belonging to the ν9+ν4ν4 and the ν9+2ν4−2ν4 hot bands were also observed in the fitted regions and measurements were made when possible.  相似文献   

14.
From known conversion coefficients and angular correlations combined with the γ-ray decay deduced from the 181Ta(p, 2n180W reaction it is found that the 1007 → 104 keV (2 → 2+) transition in 180W has mixing parameters δ1 = −0.16 ± 0.07 and δ2 = −0.64 ± 0.17 for M2/E1 and E3/E1, respectively  相似文献   

15.
The γ-ray spectra from the 60Ni(p, γ)61Cu reaction were measured for 27 isolated resonances. From these studies the Jπ assignment of the compound states in 61Cu were made. Moreover, a value for the El photon strength function k(El) = 1.03 × 10?9 MeV?3 was obtained from seven l = 0 resonances to the 16 low-lying states. This value was then compared with the theoretical estimates of El strengths as predicted from the s.p. and giant dipole resonance models. The distribution of partial radiative widths about their mean value was determined from a Monte Carlo technique and was found to be consistent with the Porter-Thomas distribution when the Γγ, ij were divided by the Eγ5 energy dependence.Values for the coefficients of the correlation R between Γλ, p and Γλ, γj and T between Γλ, yj and Γλ, γ? where fj, were computed with the values R = 0.14 and T = 0.39, respectively. Also the correlation coefficients C(〈 Γλ, yj〉, I3He, d, j) and C(〈Γλ, y?〉 Id, n, ?) yielded the values ρ = 0.87 and ρ = 0.80 respectively. All these correlations which are found to be statistically significant, imply that the (p, γ) reaction in 60Ni is partly due to direct capture such as given by valence and doorway state contributions.  相似文献   

16.
O2-broadening coefficients have been measured for 16 lines in the P and R branches of the fundamental ν3 band of 12C32S2 at room and low temperatures (298.0, 273.2, 248.2, 223.2, and 198.2 K), using a tunable diode laser spectrometer and a low temperature cell. These lines from P(62) and R(64) are located in the spectral range 1519-1547 cm−1. The collisional half-widths are obtained by fitting each observed profile with the Voigt and Rautian lineshape models. The broadening coefficients have also been calculated at all experimental temperatures using a semiclassical calculation performed by considering in addition to the electrostatic quadrupole-quadrupole interaction, a simple anisotropic contribution. Finally, from all the results, the parameter n of the temperature dependence of the broadening coefficients has been determined both experimentally and theoretically.  相似文献   

17.
The angular variation of the EPR linewidths in single crystals of (C2H5NH3)2MnBr4 has been measured as a function of temperature. The angular dependence is well characterized by δH(θ) = a + b(3 cos2θ ? 1) + c(3 cos2θ ? 1)2. The temperature dependence of the expansion coefficients is reported, and the effect of critical point fluctuations near the Néel temperature as well as a linear temperature dependence at high temperature are observed. A sharp decrease in linewidths at 160°K is attributed to a structural phase transition. The Néel temperature is determined to be 46°K (± 1°) from linewidth measurements of a powder sample. The linewidths diverge exponentially near the Néel temperature with a critical point exponent of 1.5.  相似文献   

18.
Both57Fe and151Eu Mössbauer resonances were used to study polycrystallineRBa2Cu3O7-δ samples. The dependence of hyperfine interaction parameters on the oxygen deficiency δ is studied in detail with151Eu. For57Fe spectra, a site assignment is proposed.  相似文献   

19.
We present a theory for the electron-temperature dependence T el of optical second harmonic generation (SHG). Such an analysis is required to study the dynamics of metallic systems with many hot electrons not at equilibrium with the lattice. Using a tight-binding theory for the nonlinear susceptibility χ (2)(ω,T e1) and the Fresnel coefficients we present results for the SHG intensity I (2)(ω,T e1) and its dependence on T el for Cu. Note, χ (2)(ω,T e1) rather than the Fresnel coefficients determines essentially this temperature dependence. Most interestingly we find frequency ranges where I (2)(ω,T e1) increases for small light intensities, while it decreases for large light intensities. Our theory yields also that SHG probes effects due to hot electrons more sensitively than linear optics. The results of our calculations are compared with recent experiments on Cu and Au.  相似文献   

20.
In the class of linear mappings of the abstract (i.e., concretized by nothing) Poincaré invariant LIS (linear involutive space) Laf of test functions f:XR4nf(X)∈C1 into a LIS L and in the class of linear continuous mappings of the abstract Poincaré invariant locally convex topological LIS Taf into a locally convex topological LIS we axiomatize the notions of concentration of mappings in the closed sets δ?R4n and reductions of mappings to the Borel sets δ?R4a. The axiomatization is necessary both for constructing abstract axiomatic quantum field theory and for consistent introduction of the above notions in concrete classes of generalized functions whose test function spaces contain no nontrivial finite function.  相似文献   

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