Using the perturbation method and by means of a general mathematics technique similar to the variation of constant, we present mainly some relative oscillation solution for the damping Sine-Gordon equation under certain conditions. And at the end of this paper, we give two so-called critical speeds of traveling wave. There is an interesting relationship about value and ordering of the two critical speeds.

We use squeezing and displacement operators and apply algebraic dynamics to develop a unified solution of general time-dependent two-photon algebra systems. A set of orthogonal-and-normalized solutions are derived with the ground state being the conventional squeezed state. Landau system is given as an example.

Continuous measurement theory is generalized to inhomogeneous case via the Wigner function. Applying it to two independent condensates shows that a relative phase builds up via the measurement at the expense of a decrease of the interference pattern visibility. A general pattern depending on the wave functions of the condensates is provided which can be applied to other nonlocal quantum system.

A symmetric disc-shaped torsion pendulum was designed to study the nonlinear effects of the torsion fiber. It was showed that the period of the pendulum decreases with the amplitude of the oscillation. Determination of the unperturbed period through a fit to measured data of the period variation with amplitude shows that this systematic error in the measurement of Newtonian gravitational constant G by the time-of-swing method can be reduced by an order of the magnitude at least.

Comprehensive evidence of the SU(3) octupole vibration limit in the spdf interacting boson model is found in the spectrum, E2 and El transition rates, and relative intensities in ¹⁵⁸Gd. This is a good example of a rotational nucleus with octupole vibration in the rare-earth region.

The differential cross section for ⁷Be(d, n)⁸B reaction at E_c.m. = 8.3 MeV has been measured by using a ⁷Be radioactive beam. The reaction cross section was determined to be 28 ± 3mb. The astrophysical S_l7(0) factor for the ⁷Be(p, γ)⁸B reaction was derived to be 24 ± 5 eV b through the asymptotic normalization constant of )⁸B extracted from the experimental data. This result is found to be consistent with a previous value obtained from the same reaction at E_c.m. = 5.8 MeV, implying the energy independence of this indirect method within the uncertainty.

The excitation functions of dissipative products have been measured in the reaction ²⁷Al+²⁷Al at incident energies from 114 to 127MeV in steps of 200keV. Detection angles vary continuously from 10.4° to 57.4° in laboratory system. An angular coherent width more than 40° in center of mass is obtained. The results from the analysis of excitation functions with nonself-averaging are characterized by a quasi-periodic long-range energy structure embedded in the disorder Ericson fluctuation.

Under thermodynamic equilibrium, the initial values of the quark-gluon system from relativistic nucleus-nucleus collisions are obtained. From these initial values we have studied the dilepton production on the basis of the relativistic hydrodynamic model, and found that with increasing incident energy a characteristic plateau indicating the formation of the quark-gluon plasma appears in the total yield.

The electron-energy-loss-spectrum of sodium has been measured in discrete region at a 1.5 keV impact energy and a mean scattering angle of 0°. The relative optical oscillator strength density spectrum of the valence shell of sodium was established by using the dipole (e, e) method and then normalized to the theoretical optical oscillator strength of the 3²s + 3²P excitation. The optical oscillator strengths of the 3²S → 4²P and 3²S → 5²P excitations obtained in the present work are 0.014 ± 0.002 and 0.0026 ± 0.0004, respectively. Theoretical values of optical oscillator strengths for 3²S → n²P (n = 3 - 5 ) excitations of sodium were obtained by using the relativistic configuration interaction method, which are 0.97, 0.012, and 0.0025, respectively.

Electron collision with lithium atoms is calculated by using R-matrix method. The scattering parameters are applied in the determination of the electron impact broadening and shift of the lithium resonance line 2s²S-2p²P. The width and shift are obtained based on the impact approximation. A largest discrepancy of 30 percent for the broadening width is found from a semiclassical calculation.

A fully quantum nonperturbative method is developed to describe multiphoton ionization in intense fields. It is shown that, treating the radiation field with quantum electrodynamic(QED) theory enables u s to obtain the above-threshold ionization energy distribution spectrum in analytical form firstly. Moreover, in addition to the well-known semiclassical theory, the framework presented here, derived from a QED perspective, provides a new picture of the multiphoton ionization.

A 6-boson system has been qualitatively studied based on symmetry consideration. Emphasis is placed on the ground rotation band based on the octahedron structure. In this band the L = 1 , 2, and 3 states are found to be prohibited by symmetry. Therefore there is a gap to hinder the rotational excitation of the ground state.

On the basis of the space-time Wigner distribution function, we use the least-squares fitting method to derive the relationship between effective wavefront curvature matrices and second-order mixed moments of quasimonochromatic and polychromatic pulsed paraxial beams. The expressions here are valid for both completely coherent and partially coherent light in the three-dimensional space. Finally, the fitting method is extended to the higher-order situation; from this, a novel technique for characterizing the beam phase from the moments and their derivatives is presented.

We present the first results for the analytic solution of the dissipative Jaynes-Cummings model and its application to the collapse and revival of atomic inversion. We find that the atomic inversion oscillates more and more slowly with decreasing Rabi frequency due to the cavity losses. At the same time, long drawn-out revivals after collapse are observed.

Mutually-pumped phase conjugation in BaTiO₃ crystal with two coherent incident beams has been studied experimentally for the bridge configuration. We observed that when the two pump beams are blocked individually, the transient behavior of the phase conjugation reflectivity with coherent beams was greatly different from that with incoherent beams. The phase conjugate reflectivity was sensitive to small perturbations such as vibration, exhibiting a change of as much as a factor of 10. The response time to the vibration was measured to be about 0.3s.

We describe a new method for applying a strain gradient with different profiles to convert uniform fiber Bragg gratings into linear or non-linear chirped ones. The chirping profile and the chirp rate of the fiber gratings can be controlled by simply varying the tension applied. Both the theory and experimental results are presented.

A numerical solution to the linearized ion Fokker-Planck equation is presented for large ionization-temperature ratio ZT_e/T_i ( ≥32). By reducing the equation to an eigenvalue problem through the moment approach, the frequencies and damping rates of ion-acoustic waves in ion-collisional plasmas are calculated as well as the specific heat ratios. Comparing our results with those calculated by Tracy et al. [Phys. Fluids, B5 (1993) 1430] shows that our method is accurate enough in large ZT_e/T_i plasmas.

Using dynamics equation, acceleration of out-flowing ion during dipolarization in a substorm in the magneto-tail is simulated. The main results show that: (1) The ion distribution function that is initially exponentially decreasing with increasing speed is turned into a single peak distribution, and with time the peak moves towards higher speed. (2) The peak moves along V_⊥ faster than that along V_||, and the ion acceleration mainly occurs in the middle of the dipolarization. (3) The higher the initial energy, the faster the peak moves, and the more energy is obtained by the ions. The ion energy theoretically calculated is as high as about 10² keV, this is consistent with the observation.

Through the fusing and the thermal oxidation technology, the bilayer compound film (SiO₂-PbO-Al₂O₃)/SiO₂ electret was successfully prepared on the single crystalline silicon substrate. Experiments indicated that this co-mixture laminated-layer compound film possessed unique excellent electret properties. Without any chemical modification, the surface electric potential of the sample could get the equal value of the grid voltage after corona charging and decayed no more than 5% in 270d. Moreover, not only did the samples have the excellent capability of negative charges injection and storage, but also did they have the outstanding positive ones. Thermally stimulated discharge current spectra showed that the compound film had unique, single but stable charge-trapped mechanism corresponding to T = 290°C positive/negative discharge current peak, which could be attributed to its special inner microstructure.

We proposed a simple analytical interatomic potential model by extending the framework of embedded-atom model to include the non-central three-body potentials. This model can be easily applied to treat transition metals and their alloys based on the very recently developed lattice inversion method. We used the model to calculate the phonon density of states and entropy of Fe₃AI, and the results were in agreement with the experimental data.

We study the dynamics of two-level systems under the influence of time-dependent external fields. An oscillation period describing the transition between two states is obtained analytically by the use of perturbation theory, from which the results for any special case can be derived. We illustrate two examples to show the advantage of our theory, in which the phenomenon of localization/delocalization can be addressed uniformly by oscillation period.

Based on the two-band model and nearly-free-electron approximation, the tunnel current, conductance and mag-netoresistance of the composed-barrier magnetic tunnel junctions ( MTJ ) under the forward and reverse biases are discussed, respectively, and the numerical results are compared with the experimental results of the single-barrier MTJ . We find that there exists an asymmetrical spin-polarized tunneling in this structure under the forward and reverse biases. It suggests that this type of MTJ will provide novel functions to the potential applications of traditional types of MTJ.

A doping technique to fabricate an organic quantum-well electroluminescent device is demonstrated. The fabricated single-quantum-well device consists of the following structure: an N,N’-Bis(3-methyphenyl)-N,N’-diphenyl benzidine layer for hole transportation, an 8- (quino1inoJate)-aluminum (AJq) layer for electron transportation and a light emitting layer of Alq doped with 5,6,11,12-tetraphenylnaphthacene(rubrene). The dopant rubrene serves as a potential well, whereas the undoped Alq layer serves as a barrier layer. The efficiency and luminance of the device have been significantly improved. The observed phenomena of the spectral narrowing and the emission peak energy blue-shift are a result of the recombination of carriers from the quantized energy states.

A theoretical model has been set up for evaluating the infrared absorption cut-off (λ_IR) of molecular nonlinear optical (NLO) crystals on the basis of calculated molecular infrared vibrational spectra. This model is applied to meta-dinitrobenzene (MDNB), urea, and 2-methyl-4-nitroaniline (MNA) crystals. The λ_IR values for MDNB and urea crystals are predicted to be 2.0 and 1.37μm, respectivelx which are in good agreement with experimental measurements. Although the λ_IR of MNA is experimentally unknown yet, we predict it to be 1.50μm. The theoretical analysis indicates that, while the λ_IR of MDNB arises from asymmetric torsion of N-O in the molecule, those of urea and MNA arise from symmetric N-H stretch and C-H stretch, respectively. These results should be helpful for the molecular design of novel infrared NLO crystals.

Amorphous CN:Ti films deposited by using the reactive magnetron sputtering method were annealed in vacuum under 200 to 600°C. Incorporation of Ti (less than 3at.%) has brought some new perspectives to the material. Electron-energy-loss spectrum indicates improved conductivity in CN:Ti films as in the insulating CN films. The high-resolution core-level x-ray photoelectron spectroscopy (XPS) studies show that most carbon atoms form homeopolar bonding in as-deposited CN:Ti film. While the N Is line always shrinks with increasing annealing temperature, the total full width at half maximum of C Is line decreases only at annealing temperature over 300°C when the broadening due to heterobonding formation is outdone by the effect of increasing order. An enhanced π-band feature in the valence-XPS spectra at high annealing temperatures confirms the graphitization tendency of this material.

By solving Poisson's equation for logarithmic density disturbance in three-dimensional (3D) spiral galaxies, the disturbed potential can be given on the disk. Combining it with the corresponding dispersion relation, the local gravitational stability of our galaxy is discussed here. We have generalized the Toomre's stability criterion to the more realistic 3D galaxy models. The generalized Toomre's parameter Q near the sun is 2.08 or 2.20 for two or four armed spiral galaxy models, respectively.

An independent method is proposed to determine the equation of state, ω_x ≡ p_x/ρ_x, for the dark energy component in the universe. This method is based on gravitational lensing statistics. An analytically simple expression for the optical depth of gravitational lensing in general Friedmann-Robertson- Walker cosmologies with dark energy component is derived. It is shown that for a flat universe the optical depth depends sensitively on the redshift to the source ｚ_s and the equation of state ω_x which makes the method proposed here efficient and robust.