The evolution behavior of a spin system subject to a time-varying magnetic field and the relevant two-level problem essentially exhibit like a rotation in a three-dimensional space. It is shown that the parametrization of this rotation is shifted into solving the time-dependent Schrödinger equation of a spin-1/2 system and the rotation parameters can thus be obtained by a straightforward method.

Using the mixed rescaling model, the main features of the European Muon Collaboration effect can be explained. Then the ratio of cross sections, free proton(p)-bound nucleon of Iron(Fe) to free proton-free proton, for large-P_T direct photon production is calculated.

Two-fragment correlation functions have been measured for ⁴⁰Ar+¹⁹⁷Au collisions at E/A = 25MeV. Based on the three-body trajectory calculation, a mean emission time of τ ~ 450 fm/c for light fragments was extracted from the measured correlation functions. This result suggests that the sequential decay occurs at this energy.

Stopping powers of ⁷Li ions in silicon single crystal at I-5 MeV in random and < 111 > channeling directions were determined in transmission geometry, with the uncertainties less than 6%. The measured results were compared with the available literature results and the values of TRIM-91 and TRIM-95.

K-ionization cross sections of Mo and Fe by electron impact were measured by detecting characteristic x-ray emitted by thin solid film targets of known mass thickness with a Si (Li) detector. Reflection correction of a substrate was done by bipartition model of electron transport. The experimental results are compared with theoretical calculation and empirical formula calculation.

This paper presents the cw output characteristics of Nd³⁺:KGd(WO₄)₂ (KGW) laser crystal with different Nd³⁺ concentration grown in our laboratory. The laser output at 1.067μm of KGW crystal (3x3x6mm) was obtained to be 68.9mW and the slope efficiency reached 28.8% when pumped by laser diode of power 305mW at 807nm.

We report the measured results of non-resonant nonlinearity by degenerate four-wave mixing for Cu₂O nanoparticles having central diameter of 9nm. The value of (3) obtained in a 10ns pulse experiment is 8.48 x 10^-10 esu, and the nonlinear response time of the sample is estimated to be in the order of nanosecond.

A chaotic neural network model is introduced in this letter. With the variation of a controlling parameter, the model can process the input by a content-addressable means or fall into a chaotic state. Hence the features of brain such as the clear active state and the chaotic rest state can be simply simulated.

Based on plasma dispersion of Si_1-xGe_x, the single mode waveguide modulators consisting of Si_1-xGe_x/Si and Si/ Si_1-xGe_x/Si which were grown by molecular beam epitaxy have been fabricated. For Si_1-xGe_x/Si structure, the switch current and insertion loss at wavelength 1.3 μm are 36 mA and 2.8 dB, respectively. The switching response time is 40 ns.

Optical emission spectrum has been successfully measured on a hot filament diamond growth process with substrate biasing. The emission lines of atomic hydrogen, H₂, CH and CH⁺ were observed. Effects of methane concentration on the emission intensity of observed lines were systematically studied. The experimental results suggest that atomic hydrogen and CH⁺ radicals play an important role in diamond growth, while CH radical facilitates the formation of amorphous carbon.

The calculations of the clusters, T₂₇ and T₂₇B₇ (T=Fe, Go and Ni), modelling metallic glasses have been performed using the quantum chemical linear combination of atomic orbitals (LCAO)-X_α method. The argument about the relation between magnetic moment and charge transfer has been clarified based on the calculated results.

The transformation from the octagonal lattice to a square lattice is demonstrated straightforward under the cut description by introducing a peculiar linear phason strain. The calculated lattice parameter of the β-Mn structure from the edge length of squares and rhombi forming the octagonal quasilattice is in agreement with experimental results.

A series of Nb doped KTP crystals are grown with seed flux method and flux pulling method. The results of our investigation on growth, morphology defects of the crystals are reported in this paper. We obtained the relationship between Nb contents and second-harmonic generation angles of the crystals. Noncritical phase matching has been realized by 4% Nb doped KTP crystal for Nd:YAG laser 1.06μm output.

A solvable Anderson lattice model is formulated. The exact eigenstates of model Hamiltonian are constructed by using the Bethe ansatz. The Bethe ansatz equations are obtained from the periodic boundary conditions.

The effect of electron correlation on the width of the soliton in polymer is studied. Our theory shows that the screening plays a key role in the effect of electron correlation on the width of soliton: In weak screening, the width of soliton is reduced by the electron-electron interaction; whereas, in strong screening, it will be increased. The physical reason is given at the end.

The transitions between fractional quantum Hall states are classified into three equivalence classes by virtue of the matrix theory. It is pointed out that there probably exist two new transition classes and the critical filling factors for these transitions have been calculated by exploiting the law of corresponding states.

A scheme of loop-cluster algorithm is developed for simulating an anisotropic Heisenberg antiferromagnet-the XYZ model. Results of numerical simulations are presented, suggesting that this quantum system may also be studied by using the cluster updating techniques.

The dc magnetization of Y-type zeolite containing Fe ions and that after reduction treatment were measured in the temperature range of 1.5-300K. The samples show paramagnetic behavior. The obtained value for the magnetic moment of the paramagnetic units strongly implies the existence of ferromagnetic coupling between the Fe ion at site I in hexagonal prism and the one at the nearest site I' in β cage.

The influence of Cr addition on the magnetic moment, Curie temperature and crystallization temperature of amorphous Nd₄Fe_77.5B_18.5 alloy was investigated. With increasing Cr content, the magnetization and Curie temperature decrease, but the crystallization temperature increases. It is found that the substitution of Cr for Fe can enhance greatly the coercivity of crystallized sample.

The structure and magnetostriction of Dy_0.9-xTb_xPr_0.1Fe_1.85 and Dy_0.9-xTb_xPr_0.1(Fe_0.95Al_0.05)_1.8 alloys were investigated. These alloys are substantially single phase with MgCu₂-type cubic structure. The lattice parameter and Curie temperature of Dy_0.9-xTb_xPr_0.1(Fe_0.95Al_0.05)_1.8 alloys increase steadily with increasing Tb content. Tb dependence of magnetostriction in various applied fields for polycrystalline Dy_0.9-xTb_xPr_0.1Fe_l.85 alloys exhibits a peak at x = 0.25. The magnetostriction of polycrystalline Dy_0.9-xTb_xPr_0.1(Fe_0.95Al_0.05)_1.8 alloys in high applied fields (H > 160 kA/m) and in low applied fields (H≤ 160 kA/m) exhibits a peak at x = 0.3 and x = 0.25, respectively.

The electronic structure of nanostructured SiO₂ was studied by means of ultravioletnear infrared absorption spectra. A strong and broad absorption band was observed in the wavelength range of ultraviolet-near infrared light. This band is caused by the electronic transition from the valence band to the defect energy level in the bandgap which was theoretically calculated by using molecular orbital approach. With increasing the annealing temperature, the red shift of this band was observed. The mechanism of this band is discussed.

We present room temperature femtosecond reflection studies on the photocarrier dynamics of GaAs and GaAs/AlGaAs multiple quantum wells (MQW). A rising wing with a time constant of about 5ps and an increased amplitude per carrier is observed for the MQW sample at carrier densities lower than 5 x 10¹¹cm^-2. This phenomenon is explained as the saturation of the excitonic transitions.