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71.
Time differential perturbed angular correlation measurements of the 133–482 keVγ-γ cascade of181Ta in Hf-doped YBa2Cu3O7−x
are presented. The181Hf precurser nuclei are incorporated into the sample by thermal neutron irradiation. Two quadrupole interaction frequencies
are observed in the as-irradiated sample:v
Q1=161±10 MHz with intensityf
1=75%, asymmetry parameterη
1=0.32 and damping parameter Λ1=0.42, andv
Q2=1108±40 MHz withf
2=25%,η
2=0.62, and Λ2=0.60. On annealing the sample in air at various temperaturesT
a and quenching to room temperature,f
1 remained nearly constant forT
a<600°C andv
Q1 for all annealing temperatures indicating that these are insensitive to oxygen stoichiometry. This frequency is interpreted
to be due to181Hf substitutingY sites. BeyondT
a=600°C,f
1 increased and reached a constant value of 90% forT
a=800°C. The value ofv
Q2 showed a slight variation between 1086 and 1160 MHz, whilef
2 remained nearly constant at 25% forT
a<600°C. This component is identified to be due to181Hf substituting Cu 1 sites in the Cu-O chains of YBCO. Above 600°Cv
Q2 decreased and reached a value of 808 MHz beyond 750°C. 相似文献
72.
高密度氩气的原子间相互作用与状态方程 总被引:5,自引:4,他引:1
本文从高密度气体的原子间相互作用出发进行思考,在修改范德瓦耳方程的基础上,提出了一种新的适用于高密度气体的状态方程,并用以对氩气临界区的等温压缩线进行计算,结果与实验值很符合. 相似文献
73.
The phenomenological amplitude for the reaction πN→ππN fixed by fittings to the experimental data in the energy region 0.300 ≤P
Lab≤ 500 MeV/c is used for modelling the Chew–Low extrapolation and Olsson–Turner threshold approach. It is shown that the uncritical
application of the former results in enermous theoretical errors, the extracted values being in fact random numbers. The results
of the Olsson–Turner method are characterized by significant systematic errors coming from unknown details of the isobar physics.
Received: 10 December 1997 相似文献
74.
Preparation of entangled simultaneous nonresonant atomic states through atom-field interaction
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A scheme is proposed for generating a three-atom maximal
entanglement W state. It is based on the simultaneous nonresonant
interaction of atoms with a single-mode cavity field. Our scheme is
insensitive to the cavity field, so the cavity field in our scheme
can be initially in thermal states. 相似文献
75.
S. Fumeron P. Ben-Abdallah 《Journal of Quantitative Spectroscopy & Radiative Transfer》2006,97(2):195-208
The aim of this paper is to present several features of the couplings occurring between radiative transfer and the kinetics of a moving dielectric. After determining how the velocity field affects the apparent thermo-optical properties of matter, the energy transport problem is investigated in instationary regime and the general form of transient radiative transfer equation inside a moving medium is built. Then, the model is applied to the particular case of turbulent flows: a system of two equations for mean and fluctuating radiative energies is presented, and the resolution of this system is finally carried out. 相似文献
76.
T. V. Ramakrishnan H. R. Krishnamurthy S. R. Hassan G. Venketeswara Pai 《Journal of Chemical Sciences》2003,115(5-6):767-774
Manganites of the LA1−x
Ca
x
MnO3 family show a variety of new and poorly understood electronic, magnetic and structural effects. Here we outline a new approach
recently proposed by us, where we argue that due to strong Jahn-Teller (JT) coupling with phonons the twofold degeneratee
g
states at the Mn sites dynamically reorganize themselves into localised, JT polaronsl with exponentially small inter-site hopping, and band-like, nonpolaronic statesb, leading to anew 2-band model for manganites which includes strong Coulomb and Hund’s couplings. We also discuss some results from a dynamical mean-field theory treatment
of the model which explains quantitatively a wide variety of experimental results, including insulator-metal transitions and
CMR, in terms of the influence of physical conditions on the relative energies and occupation of thel andb states. We argue that this microscopic coexistence of the two types of electronic states, and their relative occupation and
spatial correlation is the key to manganite physics.
Dedicated to Professor C N R Rao on his 70th birthday 相似文献
77.
研究了存在次近邻相互作用(耦合)时Heisenberg XX链的纠缠特性. 结果表明对近邻格点, 随着耦合常数J的变化, 次近邻相互作用的存在可能使其纠缠度增大或者减小; 而对次近邻格点, 引进次近邻相互作用却可以产生纠缠, 并且使其随着|J|的增大而增大. 近邻格点间纠缠存在的临界温度Tc随着J的增大而降低, 次近邻格点间纠缠存在的临界温度Tc随着|J|的增大而升高. 此外对纠缠W态的制备, 次近邻相互作用的存在还使得三量子位情形时W态产生的时刻改变, 而对于四量子位情形却没有影响. 相似文献
78.
Gui-Jun Yang 《应用数学学报(英文版)》2007,23(1):107-112
It is useful to know the maximum number of clear two-factor interactions in a_Ⅲ~(m-(m-k))design.This paper provides a method to construct a 2_Ⅲ~(m-(m-k))design with the maximum number of clear two-factorinteractions.And it is proved that the resulting designs have more clear two-factor interactions than thoseconstructed by Tang et al.Moreover,the designs constructed are shown to have concise grid representations. 相似文献
79.
80.
The solubilities of o-, m- and p-xylene in water were measured at 25.0°C up to 250, 385, and 50 MPa, respectively. The solubility increased with increasing pressure up to 120 MPa (50 MPa for p-xylene) and then decreased. The reaction volumes, Vo accompanying the dissolution at 0.1 MPa were estimated as –3.6±0.5, –3.4±0.5, and –4.1±0.5 cm3-mol–1 for o-, m-, and p-xylene, respectively, from the pressure dependences of the solubilities. The limiting partial molar volumes, of p- and o-xylene in water under high pressure were estimated from Vo and the molar volume of the xylene. The partial molar volumes decreased with increasing pressure. The reaction volume for the formation of intra-molecular pairwise hydrophobic interaction between the methyl groups, as proposed by Ben-Naim, is discussed for the Vo of p- and o-xylene at 0.1 MPa. 相似文献