Based on the ionic group theory, the SHG coefficients of KB5 crystal have been calculated, which leads to the following values d31=2.61×1010 esu, d32=0.07×1010 esu and d33=3.26×1010 esu. They agree fairly well with the expeimental ones. Our calculation results indicate that the hydrogen bond of (B5O10) ionic group has a large effect on the coefficients of KB5 crystal, we are therefore able to determine to how large an extent the H belongs to the ionic group. The probability of the H belonging to the ionic group is about 40-60%. Furthermore, the reasons for too small SHG coefficient of KB5 have been analysed. In addition to the small microscopic SHG coefficients of (B5O10) group, the space arrangement of (B5O10) group is in an unfavourable manner so that the largest microscopic SHG coefficients, x123, are cancelled each other. Finally, some structural requirments are proposed to search for the new type non-linear optical crystals among the B-O compounds, composed of six-membered rings, each having three borons in trigonal and tetrahedral coordination.
In this paper, the interaction of a single wave with the transit particles in a toroidal plasma is discussed. When the wave amplitude is very low, a stochastic region may exist localized in phase-space in the vicinity of phase velocity of the wave. The velocity diffusion, current drive and wave absorption will result.
The electronic structures and positron annihilation lifetimes for vacancy-like defects, H-impurity and vacancy-H, vacancy-He complex in the transition metals Cr, Fe, Ni and the noble metal Cu have been calculated, using the density functional formalism and local density approximation based on the jellium model. It is shown that positron lifetime studies can produce fingerprint speetroscopy of defect of various sizes and structures in metals.
The electrical resistivity of amorphous(Fe1-xWx)84.5B15.5(x = 0—0.1) alloys has been studied as a function of temperature between 4.2 and 300 K. The resistivity minima was observed over the whole concentration range, and the temperature of resistivity minimum Tmin showed a peak at x=0.06. Below Tmin the resistivity showed maxima in the range x=0.02—0.1. The temperature of resistivity maximum Tmax is between 26 and 35 K. The low temperature resistivity anomaly may originate from Kondo-like effect and RKKY interaction between localized magnetic moment.
In order to explain the experimental results of resistivity minima in Au1-xNix alloys (x=0.30-0.42) at low temperature, we propose a model of the alloy with dilute spin clusters in the paramagnetic state based on the s-d interaction. The resistivity contribution from the electron scattering by isolate spin clusters and by spin clusters with a ferromagnetic RKKY interaction are considered. Combining with the phonon contribution, derived from the experimental data of ρi(T) of Au-Cu or Au80Ni20 alloy, we obtain a resistivity minimum. The calculated total resistivity ρ(T) is in good agreement with the experimental result. It is shown that a decrease in ρ with increasing temperature below Tmin is mainly attributed to the Kondo effect caused by isolate spin clusters. The electron scattering from coupled spin cluster pairs gives a much smaller contribution to the resistivity, which exhibits a T-1 temperature-dependence and decreases rapidly with increasing temperature. So the experimental relults of ρ(T)-ρi(T) in Au1-xNix alloys (x=0.30-0.42) show a log T temperature-dependence over a wide tempera-ture range.
Random walks on random lattices with traps is treated by continuous time random walk (CTRW) method. The equation of walker's survival probability P(t) is obtained in the general case that the walker can decay spontaneously and is able to escape from the well after trapping. In the case of deep traps, the series solution for all time and arbitrary trap concentration with the waiting time distrubution density ψ(t) = ααt-(1-α) exp(-ata), 0 <α≤ 1, is given. Recognizing the experimental facts and Ngai's low energy excitations theory, we point out the importance of dynamic coupling. To describe this dynamic coupling, a theory of CTRW on real random lattices is proposed. In this approach the physical picture is completely different from the curresnt CTRW theory.
UPS, XPS, AES and LEED have been applied to study the samples prepared by low energy N+(0.5keV) sputtering slightly the clean cleaved surface of 2H-MoS2 (0001). From UPS (He Ⅰ, He II) spectra the shifts of EF of d band were observed. A "shoulder" or a band tail above the top of the d(z2) band raised with the time of ion bombardment so that the shape of the d(z2) band became broad. The new state showed chemically active to O2 exposure at room temperature. We propose that these shoulder states arise from the new unsaturate bonding d-electrons of Mo atoms around the vacancies of S at the outermost layer of the surface. This new surface electronic state may be correlated with the catalysis active site for hydrodesulfurization (HDS).
In this paper, the universal functions h(x), D(x), and the universal constants δ, K, which describe the critical behavior of the period-n-tupling sequences, arc discussed and Calculated. The niumerical results of δ, K, h(x), D(x) for R*n, (RL)*n, (RL2)*n, (RLR2)*n, (RL2R)*n and (RL3)*n are obtaired.
The vortex dynamics of superfluid helium filns at the Kosterlitz-Thouless phase transition is generalized to the case of spherical surfaces and is applied to interpret the torsional oscillator experiments of Bishop et al. on Vycor glass.
A direct measuring method of multiple quantum relaxation in the AX systems without 2D is proposed. The approach like those of routine measurements of relaxation time is simple and accurate. The cross correlation coefficient of fluctuation magnetic field, which is not obtainable with single quantum NMR alone, is deduced from the multiple quantum relaxation times measured by this method. The unique mechanism of multiple quantum relaxation in AX systems is also discussed.
A three layer series-parallel model of the Voltage Shorted Compaction (VSC) method for conductivity measurement of organic conductor was proposed. According to this model, the mathematical expressions of conductivity and temperature dependence of conductivity of VSC device was obtained as well as the intrinsic properties of VSC measurement. Furthermore, the technical point for preparation of VSC device was dis-cussed.
In this paper, we define a coboundary operator acting on the cochain in gauge potential space and establish a formula about Chern-Simons coboundary. The result can be employed to obtain the non-abelian anomaly, the gauge invariant Wess-Zumino effec-tive action and the Schwinger term etc. We show that the present approach covers Fad-deev's, Song's, and Zumino's approaches.
In this paper, under the conditions: 1014 GeV≤Mu≤1019 GeV, 300 GeV ≤Λhc≤l TeV, we show that, in the models of confining weak interaction, the hypercolor gauge groups SU(N) satisfy N≤3, and grand unification gauge groups are possibly SU(N) N≥7 SU(N)×SU(N) N≥4, SO(14) and SO(18).
UV-Photoelectron spectroscopy (UPS) and X-ray photoelectron speetroseopy (XPS) were used to study the electronic structure of WC, Pt and W, and high sensitive magnetometer was employed to measure the temperature dependence and field dependence of magnetic susceptibility of WC and W in the temperature range 1.5-300K. The susceptibility of W did not change with temperature, it exhibits the behaviour of Pau-liparamagnetism. But WC was entirely different, for which the Curie's law was valid. Because unpaired spins exist in WC, we made the following hypothesis: Due to the influence of carbon in WC, 5d electrons of W were no longer be itinerent thoroughly. Like Pt, part of their valence electrons became localized. The appearenee of localized electron in WC is the cause of behaving platinum-like catalystic activity.
The position-space renormalization group method is employed to investigate the order-disorder transitions in the W(112)p(2×1)-O system. The recursion relations are based on the periodically continued cluster of four cells with four sites each. We consider the pairwise interactions between nearest, nextnearest neighbours as well as the three-particle and four-particle interactions and formulate the relationships between renormalized coupling parameters K′a and interaction constants Ka. From the renormalization iteration, we find the fixed point Ka* and the critical temperature Tc for various monolayer coverages. The phase diagram of the W(112)p(2×l)-O overlayer obtained is found to be in agreement with the existing experimental results.
AES and photoelectron spectra obtained with synchrotron radiation have been used to study the orientation dependence of oxygen adsorption on a cylindrically shaped Si single crystal. At 350 K for 2L exposures, the results revealed that the orientation dependence of the adsorption oxygen amount is comparatively weak, and it ean be understood in terms of step-enhanced adsorption. At intermediate exposures of ～10L, the penetration of oxygen atoms into the crystal lattice was found mainly on (111) orientation. This fact supports a "defect"-type model for the Si(lll)-(7×7) reconstruction.
The interaction of a three-level atom initially in the common upper state with two initially coherent fields is investigated. Approximate analytic solutions for mean atomic level occupations and photon numbers are given, which exhibit collapse, revival and initial oscillation period explicitly. These are compared with the results of numerical, calculation, they agree satifactorily.
This paper introduces the period-adding phenomena which occur in the unijunction transistor second order circuit. We also studied the generating process of period-adding phenomena on the phase plane and spetrum diagram.
Results of the magnetization measurements performed on the amorphous Fe13Ni67.2P4.5B15.3 alloy in the temperature range 1.5 to 300 K in fields up to 40 kOe are reported. The behaviour near the Curie temperature is found to obey second-order phase transition laws with critical indices: β=0.39±0.02;γ=1.56±0.06; δ=5.20±0.1, and the ferromagnetic Curie temperature Tc = (180.4 ± 0.2)K. Within experimental error the critical indices satisfy the scaling law relationship γ=β(δ-l). The data satisfy the magnetic equation of state characteristic of a second-order phase transition in the temperature range 168 to 192 K. Above 270 K, the paramagnetic susceptibility obeys the Curie-Weiss law. From the Curie constant c, we obtain the effective magnetic moment peff=3.19 μB.
The influence of in-plane fields on the formation of hard bubbles in epitaxial garnet films by using single-pulse bias field was investigated in some detail. A critical in-plane field H0in which is related to the parameters of bubble films, was discovered. When Hin>H0in, formation of hard bubbles no longer occurs. Three physical processes, i.e. the increase, quick decrease and slow decrease of the demarcation field for soft and hard bubble formation H[b] with in-plane fields can be qualitatively interpreted in terms of the effect of in-plane field on stripe domains, as well as the formation of multifingered domains.
In this paper, the diffraction bands and spots experimentally observed when a laser beam passed through a KIO3 single crystal are reported. The bands and spots are formed by the diffracted beam, the plane of polarization of which rotates 90°with respect to that of the incident beam. The temperature dependence of the diffracted light was investigated in the region from room temperature to 240℃. It was found that when T=72℃ the intensity increased abrupty, when T=212℃ it decreased ;altnost to zero, and when T>212℃ no diffracted light was observed. The two temperatures, 72℃ and 212℃, determined from the anomaly of the intensity dependence, are in agreement very well with the phase transition temperatures of KIO3 crystals reported in the literature.