Theoretical calculation of energy levels and radiative lifetimes of Tl I

Considering the perturbation, the results of theoretical calculation of five Rydberg series energy levels 6s2ns^2S1/2 （n = 7 - 20）, 6s^2nd^2D3/2 （n = 6 - 20）, 6s^2nd^2D5/2 （n = 6 - 20）, 6s^2np^2P1/2^0 （n = 7- 20）, and 6s^2np^2P3/2^0 （n = 7-20） for Tl I are presented using the weakest bound electron potential model （WBEPM） theory. Furthermore, the radiative lifetimes of this five series are also calculated. The calculated values of energy levels and lifetimes are in good agreement with the experimental results.     

Perturbations in the Spectra of the Rydberg Series of a Silver Atom

The main series of a silver atom with n = 5–70 are investigated. Perturbations of the np ² P _1/2,3/2 states with n = 10 and 17 caused by interaction with the selfionization 4d5s5p ⁴ P _1/2,3/2 states are detected. Energies of the selfionization states are determined.     

Resonant widths, line intensities and lineshapes for MQDT models with two or more open channels

Approximate analytical formulae describing the energy variation of line intensities, autoionization widths and lineshape asymmetries, are derived for a Phase-Shifted Multichannel Quantum Defect Theory model composed of two closed interacting channels coupled to two effective continua. This is accomplished by putting the two compatibility equation solutions, for the common phase shifts of the two open channels, in such a form so the resonant behavior is attributed to one of them, the other accounting for an energy dependent background. Then, the well-known procedures for the simpler case where only one continuum is considered are applied, using only the resonant solution. The method is quite general and applicable to any MQDT model with two or more open channels. The resulting analytical formulae are tested on experimental spectra of Sr, Ba and Cu and it is shown that they are valid as long as: i) The resonances are non-overlapping, ii) The direct closed channel coupling is much stronger than the indirect one through the continua and (when excitation matrix elements are involved) iii) The open channels excitation strength is smaller or at least comparable to the closed channels one. Received: 26 May 1998 / Accepted: 1st July 1998     

Non-adiabatic quantum molecular dynamics: General formalism and case study H<Subscript>2</Subscript><Superscript>+</Superscript> in strong laser fields

In Rydberg atoms subject to static and harmonic collinear electric fields, intrashell transition can be induced by the first order perturbation from a small perpendicular electric or magnetic field, or by effects of the second order in the major fields. Both mechanisms lead to resonances that are suppressed under certain conditions, and high-frequency interference oscillations in case of non-adiabatic field switching. Recent measurements of microwave ionization signals show very rich and fascinating structures similar to the ones predicted for intrashell mixing. We show that the observed ionization structures may be explained by diabatic electric-field ionization and the consistent use of perturbation theory for intrashell mixing. In particular, the dominant oscillation frequency is successfully interpreted in terms of interference between first and second order transition amplitudes. New predictions are provided. The present approach gives a comprehensive picture of intrashell transitions, which may be tested in future experiments designed to observe such transitions directly. Received 2 May 2002 / Received in final form 23 September 2002 Published online 21 January 2003 RID="a" ID="a"e-mail: Valentin.Ostrovsky@pobox.spbu.ru RID="b" ID="b"e-mail: horsdal@ifa.au.dk     

Elliptic dichroism in hydrogen ionization by a coherent superposition of two harmonics

The two-photon ionization of the hydrogen atom from its ground state by a two-colour electromagnetic field consisting of two odd harmonics of the same IR laser is analyzed. The influence of the state of polarization of the bichromatic field on the azimuthal angular distribution and the dependence of the elliptic dichroism on the photon frequencies are reported. Received 11 December 2002 Published online 29 April 2003 RID="a" ID="a"e-mail: fritz.ehlotzky@uibk.ac.at     

K2里德堡态新分类

根据里德堡轨道的nl? 特性，对理论计算和实验观察到的钾分子电子态进行了分类．这些态被划分为实贯穿和实非贯穿里德堡态．这种分类更能从本质上解释和预测实验结果．比较了这种分类法对K2的应用和对Na2、Li2的应用．     

在WBEPM理论下EuⅠ原子里德堡能级计算(英文)

依据最弱受约束电子势模型理论,计算了铕原子4f76snd6D9/2(n≥13)、4f76snd8D9/2(n≥17)、4f76snd8D5/2(n≥15)和4f76snd8D3/2(n≥21)里德堡系列能级.计算结果与实验值的最大相对误差为4×10-5,最大绝对误差是1.91cm-1,达到了较高精度,这表明文中的外推数据是可信的.     

A coincidence technique for the study of intense laser atom interactions

A new device for charged particle coincidence experiments in strong-field, short pulse laser-atom/molecule interactions is presented. The device consists of a single time of flight spectrometer, common for both positive and negative charge detection. Experimental parameters required for the use of the device in the high intensity regime are discussed. A demonstration of electron-ion coincidence measurements in the interaction of Xe atoms with 60 fs laser pulses at 800 nm and an intensity of W/cm² is reported. Received 22 November 1999     

Master equation of the reduced statistical operator of an atom in a plasma

We use the nonequilibrium Liouville equation to derive the master equation for the reduced statistical operator in a heat bath represented by a many-particle environment. Focusing on the case of a weak system-bath coupling, we consider the Born-Markov approximation of the master equation and compare the result to different approaches. The master equation is elaborated for the special case of an atom as a reduced system in a plasma background. We find that the dynamical structure factor determines the effect of the plasma on the reduced system. We consider the operator equation in the atomic eigenstate and in the phase-space representation, which yields two limiting cases: quantum mechanical behavior similar to the isolated atom for the lower strongly bound levels and a semiclassical one for highly excited Rydberg levels. __________ Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 154, No. 1, pp. 31–62, January, 2008.     

The dynamical properties of Rydberg hydrogen atom near a metal surface

The dynamical properties of Rydberg hydrogen atom near a metal surface are presented by using the methods of phase space analysis and closed orbit theory. Transforming the coordinates of the Hamiltonian, we find that the phase space of the system is divided into vibrational and rotational region. Both the Poincaré surface of section and the closed orbit theory verify the same conclusion clearly. In this paper we choose the atomic principal quantum number asn=20. The dynamical character of the exited hydrogen atom depends sensitively on the atom-surface distanced. Whend is sufficiently large, the atom-surface potential can be expressed by the traditional van der Waals force and the system is integrable. Whend becomes smaller, there exists a critical valued _c. Ford>d _c, the system is near-integrable and the motion is regular. While chaotic motion appears ford<d _c, and the system tends to be non-integrable. The trajectories become unstable and the electron might be captured onto the metal surface.