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Semiclassical calculation of ionisation rate for Rydberg helium atoms in an electric field

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Chinese physics B 2011年第1期20卷 328-332页

作者：王德华 college of physics Ludong University

The ionisation of Rydberg helium atoms in an electric field above the classical ionisation threshold has been examined using the semiclassical method, with particular emphasis on discussing the influence of the core scattering on the escape dynamics of electrons. The results show that the Rydberg helium atoms ionise by emitting a train of electron pulses. Unlike the case of the ionisation of Rydberg hydrogen atom in parallel electric and magnetic fields, where the pulses of the electron are caused by the external magnetic field, the pulse trains for Rydberg helium atoms are created through core scattering. Each peak in the ionisation rate corresponds to the contribution of one core-scattered combination trajectory. This fact further illustrates that the ionic core scattering leads to the chaotic property of the Rydberg helium atom in external fields. Our studies provide a simple explanation for the escape dynamics in the ionisation of nonhydrogenic atoms in external fields.

关键词： ionisation rate closed orbit theory core scattering pulse train

Investigations on analytic potential energy function, spectroscopic parameters and vibrational manifolds (J = 0) of the SD + (X^3 Σ^- ) ion

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Chinese physics B 2009年第2期18卷 558-564页

作者：张金平施德恒孙金锋刘玉芳朱遵略马恒 college of physics & Electronic Engineering Xinyang Normal University college of physics & Information Engineering Henan Normal University

This paper investigates the spectroscopic properties of the SD^＋（X^3∑^-） ion by employing the coupled-cluster singles-doubles-approximate-triples [CCSD（T）] theory combining with the quintuple correlation-consistent basis set augmented with diffuse functions （aug-cc-pV5Z） of Dunning and co-workers. The accurate adiabatic potential energy function is obtained by the least-squares fitting method with the 100 ab initio points, which are calculated at the unrestricted CCSD（T）/aug-cc-pV5Z level of theory over the internuclear separation range from 0.09 to 2.46 nm. Using the potential, it accurately determines the spectroscopic parameters （De, ωeХe, αe and Be）. The present De, Re, We, ωeХe, αe and Be results are of 3.69119 eV, 0.13644 nm, 1834.949 cm^-1, 25.6208 cm^-1, 0.1068 cm^-1 and 4.7778 cm^-1, respectively, which are in remarkably good agreement with the experimental findings. A total of 29 vibrational states has been predicted by numerically solving the radial Schrodinger equation of nuclear motion when the rotational quantum number J equals zero. The complete vibrational levels, classical turning points, inertial rotation and centrifugal distortion constants are reported when J = 0 for the first time, which are in good accord with the measurements wherever available.

关键词： spectroscopic parameter vibrational level inertial rotation constant centrifugal distortion constant

Third-order optical intensity correlation measurements of pseudo-thermal light

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Chinese physics B 2014年第9期23卷 148-153页

作者：陈希浩吴炜孟少英李明飞 college of physics Liaoning University Laboratory of Optical physics Institute of PhysicsChinese Academy of Sciences

Third-order Hanbrury Brown-Twiss and double-slit interference experiments with a pseudo-thermal light are performed by recording intensities in single, double and triple optical paths, respectively. The experimental results verifies the theoretical prediction that the indispensable condition for achieving a interference pattern or ghost image in Nth-order intensity correlation measurements is the synchronous detection of the same light field by each reference detector, no matter the intensities recorded in one, or two, or N optical paths. It is shown that, when the reference detectors are scanned in the opposite directions, the visibility and resolution of the third-order spatial correlation function of thermal light is much better than that scanned in the same direction, but it is no use for obtaining the Nth-order interference pattern or ghost image in the thermal Nth-order interference or ghost imaging.

关键词： third-order intensity correlation thermal double-slit interference pseudo-thermal light

Elastic scattering of two ground-state N atoms

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Chinese physics B 2010年第1期19卷 268-275页

作者：施德恒张小妞刘慧朱遵略孙金锋 college of physics & Electronic Engineering Xinyang Normal University college of physics & Information Engineering Henan Normal University

An interaction potential for an N2（X^1∑g^＋） molecule is constructed by using the highly accurate valence internally contracted multireference configuration interaction method and the largest basis set, aug-cc-pV6Z, in the valence range. The potential is used to investigate the elastic scattering of two N atoms at energies from 1.0×10^-11 to 1.0 × 10^-4 a.u. The derived total elastic cross sections are very large and almost constant at ultralow temperatures, and the shape of total elastic cross section curve is mainly dominated by the s-partial wave at very low collision energies. Three shape resonances are found in the total elastic cross sections. Concretely, the first one is very sharp and strong. It results from the g-partial-wave contribution and the resonant energy is 3.645 × 10^-6 a.u. The second one is contributed by the h-partial wave and the resonant energy is 1.752 × 10^-5 a.u. This resonance is broadened by those from the d- and f-partial waves. The third one comes from the l = 6 partial wave contribution and the resonant energy is 3.522 × 10^-5 a.u. This resonance is broadened by those from the g- and h-partial waves. The N2（X1∑g＋） molecular parameters, which are determined at the current theoretical level, achieve very high accuracy due to the employment of the largest correlation-consistent basis set in the valence range.

关键词： elastic scattering total cross section shape resonance molecular parameter

Parallel propagating modes and anomalous spatial damping in the ultra-relativistic electron plasma with arbitrary degeneracy

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Chinese physics B 2017年第11期26卷 76-82页

作者： H Farooq M Sarfraz Z Iqbal G Abbas H A Shah Department of physics Government College University Government college University

The dispersion relations of parallel propagating modes（Langmuir mode, right and left handed circular polarized waves） in the weak magnetic field limit ｜ω-k·v｜〉〉？ are considered for ultra-relativistic arbitrary degenerate electron plasma. The results are presented in terms of moments of Fermi-Dirac distribution. The increase in the electron equilibrium number density from negative large（weakly degenerate） to positive large（highly degenerate） values of μ/Te is observed（where μ is the electron chemical potential and Te is the electron thermal energy）. As a result, shifting of the cutoff points in all the real dispersion branches towards the higher values and increasing in the band gap between unmagnetized longitudinal and transverse modes in k-space are examined. Also, the suppression of the weak magnetic field effects in weakly magnetized right handed and left handed circular polarized waves and a decrease in the longitudinal and transverse screening effects are observed in the graphical patterns due to an increase in the equilibrium number density.

关键词： degenerate Fermi gases relativistic plasmas electromagnetic waves

Wave packet dynamics of the photodetachment of H^- near dielectric surface

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Chinese Optics Letters 2010年第6期8卷 553-556页

作者：王德华 college of physics Ludong University

The wave packet dynamics of the photodetachment of H- near dielectric surface are studied by using the wave packet evolution and the autocorrelation *** results show that the evolutions of the autocorrelation function and the wave packet in the time domain correspond well with each other. Besides,we consider the influence of the electronic state lifetime on the wave packet evolution and the autocorrelation *** simulation shows that the evolution of the photodetached electronic wave packet near the dielectric surface exhibits some properties similar to the time-resolved two-photon photoemission intensity of surface electron.

关键词： Autocorrelation Biology Computer simulation Dielectric devices Regression analysis Waves

Investigations on molecular constants of the CD(X^2Π) radical and elastic collisions between ground-state C and D atoms at low temperatures

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Chinese physics B 2009年第9期18卷 3856-3864页

作者：施德恒张金平孙金锋刘玉芳朱遵略 college of physics & Information Engineering Henan Normal University college of physics & Electronic Engineering Xinyang Normal University

The potential energy curve of the CD（X2∏） radical is obtained using the coupled-cluster singles-doublesapproximate-triples [CCSD（T）] theory in combination with the correlation-consistent quintuple basis set augmented with diffuse functions, aug-cc-pV5Z. The potential energy curve is fitted to the Murrell-Sorbie function, which is used to determine the spectroscopic parameters. The obtained Do, De, Re, ωe, ωeXe, αe and Be values are 3.4971 eV, 3.6261 eV, 0.11197 nm, 2097.661 cm^-1, 34.6963 cm^-1, 0.2083 cm^-1 and 7.7962 cm^-1, respectively, which conform almost perfectly to the available measurements. With the potential obtained at the UCCSD（T）/aug-cc-pV5Z level of theory, a total of 24 vibrational states have been predicted for the first time when J = 0 by solving the radial Schrodinger equation of nuclear motion. The complete vibrational levels, the classical turning points, the inertial rotation constants and centrifugal distortion constants are reproduced from the CD（X2∏） potential when J = 0, and are in excellent agreement with the available measurements. The total and the various partial-wave cross sections are calculated for the elastic collisions between the ground-state C and D atoms at energies from 1.0×10^-11 to 1.0 × 10^-4 a.u. when the two atoms approach each other along the CD（X2∏） potential energy curve. Only one shape resonance is found in the total elastic cross sections, and the resonant energy is 8.36×10^-6 a.u. The results show that the shape of the total elastic cross section is mainly dominated by the s partial wave at very low temperatures. Because of the weak shape resonances coming from higher partial waves, most of them are passed into oblivion by the strong total elastic cross sections.

关键词： elastic collision total cross section molecular parameter vibrational level

Passive Q-Switching of a Yb:LuVO_4 Laser with Cr^(4+):YAG:Approaching the Intrinsic Upper Limit of Repetition Rate

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Chinese physics Letters 2018年第6期35卷 28-32页

作者： Xiao-Dan Dou Jing-Nan Yang Yan-Jun Ma Wen-Juan Han Hong-nao Xu Jun-Hai Liu college of physics Qingdao University

We demonstrate a diode pumped Yb：LuVO4 laser that can be passively Q-switched by a Cr^（4＋）：YAG saturable absorber having an initial transmission as high as 99.3%.A maximum pulsed output power of 2.35 W is generated at a repetition rate of 285.7 kHz,approaching or very near the intrinsic upper limit imposed by the recovery time of the Cr^（4＋）：YAG saturable absorber,and the resulting pulse energy,duration and peak power are,respectively,8.2μJ,39.2ns and 0.209kW.

关键词： YAG:Approaching the Intrinsic Upper Limit of Repetition Rate Yb Passive Q-Switching of a Yb:LuVO4 Laser with Cr

Electric flux distribution in photodetachment of heteronuclear diatomic molecular negative ion

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Chinese physics B 2010年第2期19卷 48-52页

作者：王德华 college of physics Ludong University

The photodetachment of a hetero-nuclear diatomic molecular negative ion is studied by using a two-centre model. An analytic formula is presented for the electron flux distribution of a heteronuclear diatomic molecular negative ion. Taking HF- as an example, we calculated the electron flux distributions of this ion for various detached electron energies. The results show that the electron flux distributions exhibit oscillatory structures, which are caused by the interference effect between the two nuclei. Besides, the laser light polarization also has a great influence on the electron flux distribution. The oscillation amplitude is the largest when the laser polarization is parallel to the z-axis; when the laser polarization is perpendicular to the z-axis, the oscillation almost vanishes. This study provides a new understanding of the photodetachment of a heteronuclear diatomic molecular negative ion.

关键词： photodetachment electron flux two-centre model hetero-nuclear diatomic molecular negative ion