Vol. 38, No. 4 (1989)
1989-02-20
CONTENT
1989, 38 (4): 523-528.
doi: 10.7498/aps.38.523
Abstract +
The deviation of radial distance to shorter value in EXAFS studies of metallic glass has been analysed in this paper. Simulation calculations showed that the current error theory can not explain the deviating-to-shorter phenomenon satisfactorily. By comparing the phase-shift function of amorphous state with that of crystalline state, we conclude that in the similar system the slope of amorphous phase-shift function may be different from that of crystalline phase-shift function. Normal EXAFS data processing without evaluating this kind of difference is also a cause of the radial distance deviating-to-shorter error in the EXAFS results. A simple method of correcting the slope of the phase-shift function of the reference sample (crystalline state) has been put forward and applied to the EXAFS data processing of Cu55Zr45 metallic glass. Results are well consistent with the results obtained from X-ray abnormal scattering measurement.
1989, 38 (4): 529-533.
doi: 10.7498/aps.38.529
Abstract +
Using X-ray diffractometer equipped with a premonochromator, X-ray Huang diffuse scattering from defects in γ irradiated LiF crysial has been measured with differential and integral methods. The results show that the strain field of irradiation defects in LiF crystal is nearly isotropic.
1989, 38 (4): 534-540.
doi: 10.7498/aps.38.534
Abstract +
Deformed HI optical potentials are evaluated in sudden approximation with nucleon densities of deformed nuclei determined by the seliconsistent semiclassical calculation. The dependence of the potentials on the orientation and the possibility of pocket structure are analysed
1989, 38 (4): 541-547.
doi: 10.7498/aps.38.541
Abstract +
Modulation instability in nonlinear monomode optical fibers is studied in letail. The condition of producing modulation instability and the maximum modulational growth rate as well as other formulas about modulation instability are presented. We obtain the conclusion that modulation instability can be produced not only in the region of anormalous dispersion but also in the region of normal dispersion. We determined the appropriate range of fiber length for maintaining the modulational growth.
1989, 38 (4): 548-558.
doi: 10.7498/aps.38.548
Abstract +
In this paper, we discuss the multi-photon systems by employing the method of adiabatic elimination following the procedure of Lugiato. We come to the conclusion that, in both the "good cavity case" and the "bad cavity case", the result we get from the discussion contains the result drawn by the adiabatic elimination following the procedure of Gordon. More over, it can compute directly the correlation of the variable that has been adiabatically eliminated. Particularly in the "bad cavity case", the steady state value of the field variable correlation obtained by the method of Lugiato is different from that obtained by the method of Gordon. The method of Lugiato is self-consistent so it is much better.In the appendix, the formulae of the atomic squeezing and the multi-photon spectrum of transmitted light are presented.
1989, 38 (4): 559-566.
doi: 10.7498/aps.38.559
Abstract +
In this paper, we derive an expression of energy gain in a laser electron accelerator by using a general covariant coordinate transformation. It is pointed out that even when the external gravitational field, is absent, the electrons will still be additionally accelerated by the influence of background medium. In the vacunm case, the obtained results agree with those obtained by the Lorentz transformation.
1989, 38 (4): 567-572.
doi: 10.7498/aps.38.567
Abstract +
A theory for laser resonators with low sensitivity to thermal effect was introduced, the new analytic solution was obtained. The influence of the changing of the cavity parameters was analyzed and some important results were achieved. A monomode Nd: YAG laser was designed by our procedure and our theory was tested and verified through experiments. From the experiments, we found that the laser can operate at two different stable zones which have unequal threshold, and also that for a reasonably designed resonator, its operating state with. stability to thermal effect corresponds to the optimum TEM mode output.
1989, 38 (4): 573-578.
doi: 10.7498/aps.38.573
Abstract +
Technological conditions and basic photoele tronic properties of a-GeNx and a-GeNx:H films prepared by an rf-reactive sputtering method are reported. The IR and Raman specrta are presented. The effects of N content on ΔE and IR and Raman spectra of a-GeNx:H film are also discussed.
1989, 38 (4): 579-585.
doi: 10.7498/aps.38.579
Abstract +
The distributions of X-ray diffraction (XRD) of N2+ (180 keV) implanted Si are presented. On the basis of trial and error strain function and multilayer model, according to kinematic theory of XRD, with Levenberg-Marqardt optimization method to simulate experimental curve we computed the strain distribution as the functions of depth, dose and annealing temperature. The results are analysed and discussed.
1989, 38 (4): 586-592.
doi: 10.7498/aps.38.586
Abstract +
This paper reports the infrared and far-infrared spectra of TixY1-xBa2Cu3O7-δ (x = 0.2, 0.4) superconductors in the temperature range of 300K to 4.2K. Seven reflection peaks have been observed in the range of 50-360cm-1 and identified -to be associated with the vibrations of Ba, Cu, 0 ions, Y, 0 ions, Ti, 0 ions, and Cu-0 bonds respectively. For x - 0.2, two inversion structures were observed, but only one for x = 0.4. In the infrared spectra six reflection and three absorption peaks were observed, the intensities increase with the increase of the Ti content. We discussed the origin of the peaks and the inversion structures comparing with YBa2Cu3O7-δ.
1989, 38 (4): 593-599.
doi: 10.7498/aps.38.593
Abstract +
In this parer, the properities of the disordered superlattice was simulated by the disordered layer system. The dynamic density response function X(q, ω) was obtained with B+S equa-tion in the weak disorder limit. And the localization lengthes, the parallel and transverse conductivities were found through X(q, ω). We derived the self-consistent equation of the cif-fusion coefficients Dk(ω) which depend on the frequency ω. The results were discussed.
1989, 38 (4): 600-606.
doi: 10.7498/aps.38.600
Abstract +
This paper studies the influence of intervally impurity scattering on the condu-ctivities of the disordered layer system. The corrections of the conductivities for the effective dimensionality in the system which depend on the interlayer coupling t are obtained. It is found that the corrections of the conductivities including the intervalley impurity scattering is half as large as those which only involving the intravalley scattering. The crossover effect of dimensionality from 2-D to 3-D in the system have been studied. It is shown that the crossover behaviour depend onthe relaxation time due to the intervalley scattering τ′. For t0)/(τ′))1/2, the sys-tern behave as a two dimensional one, for t> 1/τ((τ0)/(τ′))1/2 the system behave as thoughit were a 3-D one.
1989, 38 (4): 607-613.
doi: 10.7498/aps.38.607
Abstract +
The crystal structure, electronic transport properties in normal states, and superconductivity of a series of sample YBa2Cu3-xMxO7-y, (M = Zn,Ni, 0≤x≤0.3) have been studied, and a more direct evidence of preferential substitution of Zn for Cu(2) is obtained. In addition, an orthor-hombic(Ⅰ)-to-orthorhmbic(Ⅱ) structural transition in Zn-doped system as well as the effect of electronic localization in Ni-doped system is observed. The investigation shows that the Zn2+ may replace Cu(2) preferentially, but no such replacement for Cu by Ni was found. The role of Cu-O planes and chains on superconductivity is discussed. The importance of the coupling between Cu-O sheets and chains for high Tc superconductivity are noticed.
1989, 38 (4): 614-618.
doi: 10.7498/aps.38.614
Abstract +
For the Heisenberg model in the S=1/2 ferromagnetic theory, We constructed the proper Lagrangian function and chose the Boson quantum condition. The temperature Green's functions are computed by the stochastic quantization method, they are in agreement with those obtained by using the other methods.
1989, 38 (4): 619-628.
doi: 10.7498/aps.38.619
Abstract +
There is an acceleration term in the generalized Fokker-Planck equation, which describes the ourrent generation and the radial motion of electrons driven by lower-hybrid waves. The effects of the acceleration on the evolution of the distribution function, the coupling mechanism between the waves and the electrons and the wave-driven radial transport are discussed.
1989, 38 (4): 629-636.
doi: 10.7498/aps.38.629
Abstract +
The low frequency interchange mode and d ift wave in a hot electron plasma are analyzed by using the Vlasov equation, and the effect of hot electrons is discussed. The stabilization of the drift wave occurs when α～30%, and the stabilization of the interchange mode occurs when α～10%, where a is the fraction of hot electrons. The influences of ion Larmor radius, density gradient and temperature of plasma, wavelength of perturbation, and magnetic curvature, on the stability are discussed. Comparing with the results of the strongly collisional drift wave derived from the MHD approximation, the collisionless drift wave can be stabilized by the ho electrons more easily.
1989, 38 (4): 637-644.
doi: 10.7498/aps.38.637
Abstract +
The time evolution of electron temperature in plasma current rising phase on CT-6B Tokamak is estimated by the history method for oxygen impurity lines. The time variations of line emissions of OII-OV1 in VUV region are measured by one-meter grazing incidence vacuum spectrometer and the electron density is measured by using FIR HCN laser interferometer. The switch-on time of each line emission is used for estimating electron temperature. The influences of oxygen impurity influx rate and confinement time on intensity and switch-on time of line emissions are surveyed numerically. The estimated electron temperatures arc around 3.6, 5.6, 7.3, 10.8 and 21 eV, respectively at 0.36, 0.56, 0.66, 0.90 and 1.4 ms after the start of discharge, which indicate the plasma temperature in central region.
1989, 38 (4): 645-647.
doi: 10.7498/aps.38.645
Abstract +
We generalize the transverse XY model to the case with NNN interactions. The Hamiltonian is H=g∑nσn2-∑n ((1+γ)/2σnxσn+1x+(1-γ)/2σnyσn+1y)-λ∑n ((1+β)/2σnxσn+2x+(1-β)/2σnyσn+2y). It is shown that the model with β=0 and γ≠0 isequivalent to the free fermion field in the vicinity of critical point, so that it belongs to the Ising universality class.
1989, 38 (4): 648-652.
doi: 10.7498/aps.38.648
Abstract +
A quantum nonlinear Schr?dinger model with the most general supermatrices, having structure (n-k,k)(m-l,l), is studied by using the quantum inverse scattering method. The eigenstates of the Hamiltonian and the infinite number of the conserved quantities of the system are discussed, In particular, the N-particle bound states with the mixture of bosons and fermions are found. The energy of the N-particle eigenstate are ∑j=1Nλj2 and Np2-(c2/12)N(N2-1) for the scattering stateand the bound state respectively.
1989, 38 (4): 653-658.
doi: 10.7498/aps.38.653
Abstract +
In this paper,based on the linear transformation of optical variable operator, the relation equation expressing the relationship between optical matrices and optical operators is generalized into an optical general relation equation. By using the eigen optical variable operator, the optical general relation equation may be simplified to the reduced optical general relation equation hence a general method, the method of single lens imaging analogy, is obtained This method can be used in solving the relation equaion to find optical point-spread operator.
1989, 38 (4): 659-664.
doi: 10.7498/aps.38.659
Abstract +
An improved Monte Carlo renormalization group method is applied to three-state and four-state Potts models on two-dimensional random triangle lattice. Their fixed points and critical exponents are analysed. The critical exponents obtained are consistent with the theoretical analytical values.
1989, 38 (4): 665-669.
doi: 10.7498/aps.38.665
Abstract +
Neutron diffraction experiments on Y(Ti, Fe)12 have been carried out to study the crystal structure and magnetic properties of Y(Ti Fe)12 The crystal structure of Y(Ti Fe)12 belongs to the ThMn12 type structure, its space group is 14/mmm. Fe and Ti are distributed on three nonequivalent crystallographic sites, and they occupy some sites preferentially. Finally, the results are discussed primarily.
1989, 38 (4): 670-674.
doi: 10.7498/aps.38.670
Abstract +
The transmittance curves of ZnWO4 single crystals grown by Czochralski method have been measured. We suggest that the existense of oxygen vacancy is the basic reason for the rosy color of the crystal. The position of the optical indicatrix, the refractive indices in the visible wavelength region and the Sellmeier's equations have been determined more accurately.
1989, 38 (4): 675-678.
doi: 10.7498/aps.38.675
Abstract +
The valence-band spectra of Nb-Ni glasses during crystallization have been studied systematically by means of UPS technique and X-ray diffraction. The double peaks in valence-band spectra of NbNi2 are discussed.
1989, 38 (4): 679-682.
doi: 10.7498/aps.38.679
Abstract +
The cohesive properties of A13V in the two different structures (DO22 and Ll2) were in-vestigated by means of local density total energy approach. The calculated lattice constant (α= 3.72?, c = 8.20?) for A13V in DO22 structure is in agreement with experiment, the bulk modulus (1.3 Mbar) is consistent with the experimental Young modulus for Al3Ti, and the calculated formation energy (29±1 kcal/mol) agrees reasonably well with experimental value (26.0kcal/mol).
1989, 38 (4): 683-688.
doi: 10.7498/aps.38.683
Abstract +
Liquid mixtures were studied by Brillouin and Raman Scattering. The curves of sound velocity vs. mixture ratio demonstrate various behaviours, some show monotonous change, others show maximum or minimum. From Raman spectrums, we found that some molecular vibration frequencies are shifted by mixing. We explained these phenomena and got informations about molecular interactions in the mixtures.
1989, 38 (4): 689-693.
doi: 10.7498/aps.38.689
Abstract +
The XPS, oxygen content and resistance-temperature relationship of YBa2Cu3-xAlxO7-y single phase system are determined. The experimental results show that Al can possibly substitute the Cu and Y positions in 1-2-3-phase partially. Because of the existence of Al3+, the content of oxygen increases, the environment of oxygen tends to be uniform, the difference of the two states of O15 in XPS is indistinct. The presence of Cu3+ is clearly observed.
1989, 38 (4): 694-698.
doi: 10.7498/aps.38.694
Abstract +
The microstructure, superconductivity, and the superconducting current-carrying properties of YbxY1-xBa2Cu3O7-y are investigated systematically. We find that, when the content of Yb increases, Tc changes slightly, but the critical current density decreases with the grain size obviously. The results suggest that just decreasing the grain size can not increase the critical current density of such granuler superconductors in which the couplings among grains are weak.
