Occurrence of Superdeformation in Even-Even Isotopes of Zn

Occurrence of superdeformed (SD) shape from the relationship between the collective rotation and the pairing correlations is investigated in the relativistic mean field theory framework. It is found that pairing correlation plays an important role in the occurrence of SD shape. It is also shown that the SD band of 66^Zn is more difficult to be observed than that of 60^Zn experimentally.     

Anomalous behaviour of long-time increase in diffraction efficiency of photorefractive grating in Ce：BaTiO3 in dark

Anomalous long-time increase of the diffraction efficiency is observed in dark-decay experiments of photorefractive gratings in Ce：BaTiO3. It is deduced that a phase-conjugate beam is induced by the writing beam at acute angle to the ＋c axis of the crystal and it interferes with the other writing beam to form a second grating which is perpendicular to the first grating formed by the interference between two writing beams. The rising behaviour of the diffraction efficiency results from the different decay rates of these two photorefractive gratings. Furthermore, a simplified model of two gratings, both induced by two deep traps, is proposed to account for this phenomenon and the fitting results agree well with the experimental results.     

Propagation Control of Soliton Trains in Dispersion-Shifted Fibres in the Presence of Third-Order Dispersion

The evolution of soliton trains in dispersion-shifted fibres (DSFs) in the presence of third-order dispersion (TOD) is investigated. The results show that the collision of neighbouring solitons in the trains can be suppressed by means of a proper TOD, but the maximum transmission distance (or bandwidth) is limited by the increasing soliton separation that results from the TOD. It is also shown that the separation can be suppressed by adjusting the initial phase or amplitude difference between the solitons. These results are helpful to re-establish the potential application of the soliton-based optical-communication systems in DSFs.     

Ellipticity of motion of particle in field of inhomogeneous plane wave

lIntroductionThephysicalmodelofinhomogeneousplanewaveofacousticsisusedtostudythewavepropagationinthermoviscoelasticmaterials.Inrecentyears,alotofworksandsomesignificafltresultshavebeenpublished,inwhichthegeneration,propagation,reflectionandrefractiononaninterfacefortheinhomogeneousplanewaveaswellastomeasurethecoefficientsofviscosityofmaterialsbyusingthemodelofinhomogeneousplanewavewerec..ce...dt1-2o].Inthispaper,under.thehighfrequency,westudytheellipticalmotionofparticleinthefieldofinhomogeneo…     

Interpretation of the change in optical constants of different compositions of Ge–Se–In in terms of cohesive energy

Compositional dependencies of the optical and physical properties of as-deposited amorphous Ge_xSe_90?xIn₅ films (with 5≤x≤30 at%), prepared by thermal evaporation have been studied. The optical energy gap $E_g^{opt}$ is derived from Tauc's extrapolation in the strong absorption region in terms of transmission and reflection spectra. The relationship between the optical gap and chemical composition of the Ge_xSe_90?xIn₅ (with 5≤x≤30 at%) amorphous system is discussed in terms of the chemical bond approach. The refractive index, n and film thickness, d have been determined by an envelope method using transmission spectra. It is observed that the refractive index, n of Ge_xSe_90?xIn₅ thin films increases with increasing x, over the entire spectral range, which is related to both the increased density and average coordination number.     

Propagation of Cylindrical Waves in Media of Time-Dependent Permittivity

We present the propagation of cylindrical waves in the media whose permittivity varies with time abruptly or continuously. By the method of variable separation, we derive the general expression of electric field of TM-polarized waves in two-dimensional space with excitation of any point at any time. With this expression,the solution for a spatially and temporally distributed source can be obtained theoretically. The focusing of reflected waves in the cross section is shown when the media undergoes a sudden or continuous change. The wave propagation in time-invariant media can be considered as a special case of the media under exponential variance.     

Observation of Diffusion Process of a Water Droplet Immersed in Protein Solution in Microgravity

Pure liquid-liquid diffusion driven by concentration gradients is hard to study in a normal gravity environment since convection and sedimentation also contribute to the mass transfer process. We employ a Math Zehnder interferometer to monitor the mass transfer process of a water droplet in EAFP protein solution under micro- gravity condition provided by the Satellite Shi Jian No 8, A series of the evolution charts of mass distribution during the diffusion process of the liquid droplet are presented and the relevant diffusion coefficient is determined.     

Role of Covariance Correlation Tensor in Establishment of Criterion of Quantum Entanglement

This article discusses the role of covariance correlation tensor in the establishment of the criterion of quantum entanglement. It gives a simple example to show the powerfulness in the treatment of quantum dense coding, and illustrates the fact that this method also provides theoretical basis for establishing corresponding knotted pictures.     

Applications of γ-γ-Directional correlation measurements in studies of trace elements in plants

Perturbed --directional correlation measurements were used in a study of the uptake and transport of trace elements in plants. The results from experiments with^111mCd in plant cell systems, cytoplasm and intact tomato plants indicate that Cd, applied as Cd²⁺, is rapidly bound to cell walls.     

Binding Energies of Excitons in Square Quantum-Well Wires in the Presence of a Magnetic Field

The binding energies of the ground state of excitons in the GaAs/Ga1-xAlxAs square quantum-well wire in the presence of a magnetic field are investigated by using the variational method. It is assumed that the magnetic field is applied parallel to the axis of the wire. The calculations of the binding energy as a fimction of the wire size have been performed for infinite and finite confinement potentials. The contribution of the magnetic field makes the binding energy larger obviously, particularly for the wide wire, and the magnetic field is much more pronounced for the binding energy in a square quantum wire than that in a cylindrical quantum wire. The mismatch of effective masses between the well and the barrier is also considered in the calculation.     

Use of wavelet in specifying optics

Using power spectral density (PSD) function to specify large aperture optical components' quality of laser system is universal. But it cannot provide effective guidance to eliminate certain frequency segment error. In order to solve this problem, two-dimensional discrete wavelet transform (2D-DWT) is used to separate frequency segment error and detect the corresponding region of certain frequency segment error, which is used as feedback to a machining process. The experimental results show that the corresponding region of certain frequency segment can be found and machining can be guided effectively by using wavelet.     

Photoexcitation of Bipolarons in Conducting Polymers

We theoretically study the photoexcitation process in a conducting polymer with a non-degenerate ground state,where the carrier with out spin is a bipolaron.The dynamical simulation reveals a photoinduced phenomenon in which a positive bipolaron is split into two polarons by absorbing one photon.The relaxation time of this photoinduced bipolaron split is about 40fs.It is predicted that this photoinduced phenomenon can be detected experimentally by observing the change of magnetic susceptibility.     

The Theses of Doctorate in 2003

The Isospin Effect an Intermediate Energy Heavy Ion Collisions and Halo Nuclear Structure Guo Wenjun. Experimental Investigation on the Isospin-dependent Properties of Hot Nuclei in Heavy-ion Collisions at Intermediate Energies Hu Rongjiang.     

Interpretation of Plateau in High-Harmonic Generation

The plateau in high-harmonic generation is investigated in the frequency domain. Probability density of an electron in an electromagnetic field is obtained through analysing the quantlzed-field Volkov state. The plateau of hlgh-harmonic generation reflects the spectral density of the electron at the location of nucleus after above-thre shold ionization.     

Diffusion of Hf in α-Zr

The diffusion of Hf in -Zr has been studied in the temperature range 773–1115 K for the first time using the Rutherford backscattering technique. For this purpose we have used 250 Å thick Hf films, which were deposited on two types of Zr samples. Our results show that in both cases, the diffusion coefficients follow curved Arrhenius plots. For the pure Zr material the diffusion coefficients are systematically lower than for Zr samples of lower purity. These results indicate that the Hf diffusion mechanism is at least partially of extrinsic character. Finally it should be mentioned that the present data lie significatively below the values of self-diffusion in -Zr.     

Photoformation of π mesons in carbon

A calculation is made of the total cross section of the¹²C(,^–)¹²N reaction as a function of the energy of the quanta, by means of the technique of nonrelativistic diagrams, which permitted the differential cross sections of this reaction and the electroexcitation of the 15.11-MeV level in¹²C to be directly related. For the amplitude of the photocreation of-mesons in the nucleons we take the relativistic- and gradient-invariant expression, which follows from the model of the algebra of currents with physical pions. An analysis is made of the effect of the contributions of (1232) resonance and vector mesons to the amplitude, and also the different choice of the reaction kinematics in the nucleon.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 46–50, September, 1979.     

Analysis of Aberrations in Laser-Focused Nanofabrication

Based on the semi-classical model, we analyse the motion equation of chromium atoms in the laser standing wave field under the condition of low intensity light field using fourth-order Adams-Moulton algorithm. The trajectory of the atoms is obtained in the standing wave field by analytical simulation. The image distortion coming from aberrations is analysed and the effects on focal beam features are also discussed. Besides these influences, we also discuss the effects on contrast as well as the feature width of the atomic beam due to laser power and laser beam waist. The simulation results have shown that source imperfection, especially the transverse velocity spread, plays a critical role in broadening the feature width. Based on these analyse, we present some suggestions to minimize these influences.     

Diffusion of Ta in α-Ti

The diffusion of Ta in the hcp (α) phase of high-purity Ti (99.99%) was studied at different temperatures from 911 K up to 1123 K. The Rutherford Backscattering Spectrometry (RBS) and Heavy Ion RBS (HIRBS) techniques were used to obtain the penetration profiles. The evolution of the diffusion coefficient, D, as a function of temperature follows prediction of the Arrhenius law. The activation energy of the diffusion process is (318±7)kJ/mol, similar to that corresponding to self-diffusion in α-Ti. On the other hand, the measured values of D are systematically lower than those corresponding to self-diffusion by a factor of approximately 5. This reduction could be explained by taking into account the mass difference between Ta and Ti. An increase of the diffusion coefficient was measured when the diffusion proceeds on a less pure Ti (99.9%) matrix. This increment is higher at lower temperatures. Received: 12 November 2001 / Accepted: 12 March 2002 / Published online: 5 July 2002 RID="*" ID="*" RID="*" ID="*" RID="**" ID="**"Corresponding author. Fax: +54-11/6772-7362, E-mail: dyment@cnea.gov.ar RID="*" ID="*"Members of the Carrera del Investigador Científico del Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina     

The Theses of Master in 2003

Investigation of Double-electron Processes in Slow Collisions of Highly Charged Ions with He Cao Zhurong. Studies of the High-spin Level Structures in ^134Ba and ^135La Luo Peng.