低损耗玻璃光波导的溶胶-凝胶法制备

By means of the relation of ionicity and the ionization energies of hydrogenlike atoms, the soft X-ray spectra are calculated for the hydrogenlike sodium, magnesium and aluminium atoms. The calculated results are in good agreement with the experiments.     

类氢硅离子软X射线谱的计算

利用高剥离态类氢离子的势函数模型，计算了类氢Si离子的软X射线谱及 其精细结构，计算结果与实验值进行了比较。     

交换势对光电离截面的影响

利用相对论平均自洽场理论,研究了光电离截面在不同交换势下的差异,在对这种差异进行分析的基础上,对其变化规律做了较详细的理论说明.计算结果表明:光电离截面随交换系数的增大而增大;电子所感受到的平均核势场越小,交换势所起的作用则相对地有所增加,从而对光电离截面的影响更大.     

类氢离子的新势函数模型

给出了类氢离子的一个新势函数,该势函数包含了离子电离度效应,求出了相应的离子能级与波函数。用该理论研究了高离化态的类氢氟离子和类氢氖离子的部分激发光谱,计算结果与实验结果吻合很好。     

The influence of nuclear structure on the Lamb shift in hydrogenlike heavy atoms

We evaluate and list the various contributions to the Lamb shift in hydrogenlike heavy atoms which arise from parameters describing shape, size and structure of the nucleus. We compare these contributions with those obtained from quantum electrodynamics. It is found that in heavy nuclei, nuclear contributions depending on experimental parameters and nuclear models are of the same size as QED contributions of order a². Therefore, in these systems the theoretical predictions for binding energies are limited by the exact knowledge of the nuclear parameters. In addition, we tabulate all corrections contributing to the 1s_1/2 Lamb shift in hydrogenlike Pb and U. This revised version was published online in August 2006 with corrections to the Cover Date.     

Exact two-loop vacuum polarization correction to the Lamb shift in hydrogenlike ions

We present a calculation scheme for the two-loop vacuum polarization correction of order to the Lamb shift of hydrogenlike high-Z atoms. The interaction with the external Coulomb field is taken into account to all orders in . By means of a modified potential approach the problem is reduced to the evaluation of effective one-loop vacuum polarization potentials. An expression for the energy shift is deduced within the framework of partial wave decomposition performing appropriate subtractions. Exact results for the two-loop vacuum polarization contribution to the Lamb shift of K- and L-shell electron states in hydrogenlike Lead and Uranium are presented. Received: 10 August 1997 / Revised: 31 October 1997 / Accepted: 18 November 1997     

Measurement of the beta+ and orbital electron-capture decay rates in fully ionized, hydrogenlike, and heliumlike 140Pr ions

We report on the first measurement of the beta+ and orbital electron-capture decay rates of 140Pr nuclei with the simplest electron configurations: bare nuclei, hydrogenlike, and heliumlike ions. The measured electron-capture decay constant of hydrogenlike 140Pr58+ ions is about 50% larger than that of heliumlike 140Pr57+ ions. Moreover, 140Pr ions with one bound electron decay faster than neutral 140Pr0+ atoms with 59 electrons. To explain this peculiar observation one has to take into account the conservation of the total angular momentum, since only particular spin orientations of the nucleus and of the captured electron can contribute to the allowed decay.     

On the change of polarization of positive muons in alkali halides

Positive muons implanted in nonconducting solids form with high probability hydrogenlike muonium atoms (µ ⁺ e ^–) with properties similar to those ofU ₂-centers. The influence of superhyperfine interactions with neighbor nuclei on the evolution of the polarization of the muon is investigated theoretically. The resulting muon polarization in longitudinal magnetic fields is calculated for muonicU ₂-centers in some alkali halides.     

Polarization of the dielectronic recombination satellites including the generalized Breit interaction effects

The polarizations of dielectronic recombination satellite lines for hydrogenlike F to U ions are calculated including the generalized Breit interaction(GBI). The calculated values of the asymmetry parameter are compared with other theoretical results and good agreements are obtained for all lines except for those from the level 2s2p3P1. The GBI effects on the polarization become much stronger as the atomic number increases. However, for different lines, the GBI effects on the polarization are different.     

Spectral Properties of Endohedrally Confined Hydrogen Atom and Hydrogen—Like Ions Obtained by Using B—Spline Basis Set

A B-spline method has been used to calculate the electron structure of endohedrally confined hydrogenlike atoms.The boundary conditions were conveniently satisfied with such the method.The evolution of the energy spectrum,as function of the depth of the confining well,exhibits a “mirror collapse”.Ions with higher ionicity have more “collapse lines”,the energies change more sharply at “collapse points”,and the oscillator strengths change more violently with the depth of the confining well.     

Magnetic neutrino scattering on atomic electrons revisited

We reexamine the role of electron binding effects in the inelastic neutrino–atom scattering induced by the neutrino magnetic moment. The differential cross section of the process is presented as a sum of the longitudinal and transverse components, according to whether the force that the neutrino magnetic moment exerts on electrons is parallel or perpendicular to momentum transfer. The atomic electrons are treated nonrelativistically. On this basis, the recent theoretical predictions concerning the magnetic neutrino-impact ionization of atoms are critically discussed. Numerical calculations are performed for ionization of a hydrogenlike Ge⁺³¹ ion by neutrino impact.     

Relativistic and many-body effects in K, L, and M shell ionization energy for elements with and the determination of the 1s Lamb shift for heavy elements

We report on a calculation of K, L and M inner-shell ionization energy in atoms with atomic numbers in the range . Many-body effects are evaluated for all n =1, 2, and 3 hole states. Those include correlation and effects due to the auto-ionizing nature of the hole states (Auger shift). For high Z we add recent corrected nuclear polarization, and several second-order vacuum polarization corrections. K and L ionization energies are compared with experimental X-ray absorption edges measurements. Excellent agreement with rare gazes and metal vapor measurements is found. We also compare our calculations with X-ray transition energies for all K and L lines that involve K, L and M holes. Finally we use K X-ray lines to deduce an hydrogenlike 1 s Lamb shift for several heavy elements, with far better accuracy than has been obtained by direct measurements of hydrogenlike ions. Received: 25 February 1998 / Accepted: 31 March 1998     

Asymmetry of the natural line profile for the hydrogen atom

The asymmetry of the natural line profile for transitions in hydrogenlike atoms is evaluated within a QED framework. For the Lyman- alpha 1s-2p absorption transition in neutral hydrogen this asymmetry results in an additional energy shift of 2.929 856 Hz. For the 2s(1/2)-2p(3/2) transition it amounts to -1.512 674 Hz. As a new feature this correction turns out to be process dependent. The quoted numbers refer to the Compton-scattering process.     

Extremely short pulses via stark modulation of the atomic transition frequencies

We propose a universal method to produce extremely short pulses of electromagnetic radiation in various spectral ranges. The essence of the method is a resonant interaction of radiation with atoms under the conditions of adiabatic periodic modulation of atomic transition frequencies by a far-off-resonant control laser field via dynamic Stark shift of the atomic levels and proper adjustment of the control field intensity and frequency, as well as the optical depth of the medium. The potential of the method is illustrated by an example in a hydrogenlike atomic system.     

Resonant generation of few-cycle pulses in hydrogenlike atoms

We show the possibility to produce nearly bandwidth-limited few-cycle pulses based on time-dependent resonant interaction of an incident radiation with the bound states of hydrogenlike atoms. A time-dependence of an atomic resonance is provided by far-off-resonant laser field with intensity much below the atomic ionization threshold via time-dependent tunnel ionization from the excited states and temporal adiabatic Stark splitting of the excited energy levels. Without external synchronization of the spectral components it is possible to produce a train of two-cycle pulses at 121.6 nm with duration 800 as in atomic hydrogen.     

Doubly inelastic collisions with relativistic heavy ions and target recoil momentum spectroscopy

We consider relativistic collisions of heavy hydrogenlike ions with hydrogen and helium atoms in which the ion-atom interaction causes both colliding particles to change their internal states. Concentrating on the study of the longitudinal momentum spectrum of the atomic recoil ions, we discuss the role of relativistic and higher order effects, predict a surprisingly strong influence of the projectile's electron on the momentum transfer, and show that the important information about the doubly inelastic collisions could be obtained in experiment merely by measuring the recoil momentum spectrum.     

电离度效应对高电离态类氢离子平均寿命的影响

利用类氢离子新势函数模型,研究了电离度效应对高电离态类氢离子平均寿命的影响,计算了类氢Kr+35离子2p-8p态的平均寿命.发现电离度效应使类氢O+7-Pm+60离子各态的平均寿命相对减少0.26%～9.41%.结果对估价高电离态原子光谱和寿命的测量值有一定影响,有利于识别离子状态.     

Application of radiative electron capture for the diagnostics of spin-polarized ion beams at storage rings

It is proposed to apply the radiative electron capture into high-Z projectiles as a probe process for measuring the spin polarization of the hydrogenlike ions at storage rings. We argue that such polarization measurements are possible since the linear polarization of emitted x-ray photons is greatly sensitive to the spin states of incoming ions with nuclear spin I > 1/2. In particular, for K-shell electron capture into the hydrogenlike ions, the linear polarization of light as measured out of the reaction plane is found to be proportional to the degree of ion polarization. Detailed computations for the dependence of the photon polarization on the ion spin states and projectile energies are carried out for the electron recombination into hydrogenlike Bi 82+ ions.     

Alignment and orientation of charge exchange excitation with polarized projectiles

The alignment and orientation of hydrogenlike excited atoms produced by electron capture in collisions of spin polarized bare atomic nuclei with atomic targets is described in terms of Stokes parameters. TheH(2p)^* excited state formed by spin polarized protons making charge exchange collisions on atomic targets is dealt with extensively for the purpose of illustration. The linear polarization and circular polarization of resulting Lyman-α when polarized protons make electron capture collision on atomic hydrogen target are plotted to compare observable aspects of different theories of electron capture.