Spin-Flip and Elastic Processes in Slow Collisions of Mesic Atoms

The reduced adiabatic hyperspherical (RAHS) basis suggested previously is used for the calculation of elastic and spin-flip cross sections in the processes (aμ) _F + a → (aμ) _F′ + a, a = (p, d, t), for collision energies 10⁻³ ≤ ε ≤ 10² eV. The rapid convergence of the method is demonstrated. A comparison of the obtained results with previous ones is presented. This revised version was published online in August 2006 with corrections to the Cover Date.     

Energy Losses in Collisions of Relativistic Structural Heavy Ions with Atoms

A nonperturbative theory of the energy losses in collisions of structural multiply charged heavy ions moving with relativistic velocities with atoms is worked out. Within the framework of this theory, by structural ions are meant ions containing partially filled electronic shells. It is such ions, having, as a rule, a considerable charge (for example, completely or partially stripped ions of uranium), that are used in many modern experiments on accelerators of heavy ions.     

Multiple Collisions of a Fast Mesic Atom with a Diatomic Molecule

Processes of ionization of the fast (μHe)⁺ mesic atom in multiple collisions with a diatomic molecule are examined. It is demonstrated that a consideration of molecule alignment can significantly increase the probability of mesic atom ionization. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 30–33, May, 2005.     

中低能速度能区离子与H,He原子碰撞中的经典电子俘获截面

Bohr-Lindhard模型被用来描述中低能速度能区离子—原子碰撞中的经典电子俘获过程。根据离子与原子的作用时间与碰撞参数的关系,建立俘获几率对碰撞参数的依赖性,碰撞参数范围被限定在俘获半径之内。在该模型的框架内,人们试图通过电子的空间分布函数来研究所有碰撞参数的贡献,但存在较为复杂的数值计算。基于Bohr-Lindhard模型,本工作提出通过简单的指数衰减函数来描述电子俘获几率对碰撞参数的依赖性,计算了Aq+(q = 2~6)-H碰撞中的单电子俘获截面和Aq+(q = 3~6)-He碰撞中的双电子俘获截面,计算结果与已有实验数据符合很好,很好地描述了低能和中能区的电子俘获截面随能量和电荷态的变化,该工作还可计算其他不同电荷态离子与He和H靶的电子俘获截面。     

Impact Excitations of Hydrogen Atoms in Collisions with Protons and Antiprotons

The direct impact excitations of ground-state hydrogen atoms by protons and antiprotons are investigated by using an impact parameter treatment. The calculations are performed within the solution of the coupled differential equations arising from the one-center atomic-orbital close-coupling approach as well as the impact parameter version of the first and second Born approximations. We have considered calculations that allow couplings to the n=1-5 states （up to g sub-levels） of the target atom as well as others, which neglect the effect of all states other than the initial and final states of the target atom. The sensitivity of the cross sections to the charge of the projectile is studied. The calculated cross sections are compared with those obtained by previous theoretical and experimental results.     

Elastic Collisions Between two Ground-State P and D Atoms at Low and Ultralow Temperatures

The PD（X^3∑^-） interaction potential is constructed using the CCSD（T） theory and the basis set, augcc-pV5Z. Using this potential, the spectroscopic parameters are accurately determined. The present Do, De, Re, ωe, ωeχe, αe, and Be are of 3.056 99 eV, 3.161 75 eV, 0.142 39 nm, 1701.558 cm^-1, 23.6583 cm^-1, 0.085 99 cm^-1, and 4.3963 cm^-1, respectively, which almost perfectly conform with the measurements. A total of 26 vibrational states is predicted when J = 0 by solving the radial Sehrodinger equation of nuclear motion. The complete vibrational levels, classical turning points, initial rotation and centrifugal distortion constants when J = 0 are reported for the first time, which favorably agree with the experiments. The total and various partial-wave cross sections are calculated for the elastic impact between two ground-state P and D atoms at 1.0 × 10^-12 - 1.0 × 10^-4 a.u. when they approach each other along the PD（X^3∑^-） potential. No shape resonances exist in the total elastic cross sections, though the peaks can be found for each partial wave until l=6. The shape of the total elastic cross sections is dominated by the s partial wave at very low temperatures. Due to the weakness of the shape resonances of each partial wave, they are all passed into oblivion by the strong total elastic cross sections.     

Collisions with Participation of Polarized Cesium and Lithium Alkali Atoms

Optics and Spectroscopy - The spin-exchange cross sections and the magnetic resonance frequency shift in collision of lithium and cesium atoms in the ground state are calculated. The calculations...     

The Fine Structure of Alkali Metal Atoms in Inelastic Collisions with Hydrogen

Optics and Spectroscopy - A method is proposed for calculating the rate constants of inelastic processes occurring during collisions of alkali metal atoms and their positive ions with hydrogen...     

Ionization of Hydrogen and Helium Atoms in Collisions with Relativistic Structural Heavy Ions

Based on the eikonal approximation, cross sections for single and double ionization of hydrogen and helium atoms in collisions with structural multiply charged heavy ions moving with relativistic velocities are calculated. In the present paper, the structural ions are taken to mean the ions with partially filled electronic shells. It is demonstrated that a consideration of the ion charge extension may noticeably change the corresponding cross sections compared to the cross sections for ionization by point ions having the same charges and energies.     

Strongest Magnetically Induced Transitions in Alkali Metal Atoms

JETP Letters - Atomic transitions in alkali metals that have zero probability in the absence of a magnetic field but have large probabilities in the presence of a magnetic field are called...     

Magnetic Resonance Frequency Shift of Na Atoms during Collisions in a Mixture of Potassium and Sodium Atoms

Technical Physics - Collisions between sodium and potassium atom in the conditions of optical orientation of potassium atoms are considered. Because of collisions, the spin exchange occurs between...     

Coulomb Deexcitation and Non-Resonant Meson Transfer from Excited States of Mesic Hydrogen Isotope Atoms

Advanced adiabatic approach is used to calculate the rates of the Coulomb deexcitation and charge transfer processes including meson transfer from a heavy isotope to a light one.     

High-Precision Calculation of the Energy Levels and Auger Decay Rates of the Metastable States of the Antiprotonic Helium Atoms

We precisely calculated the energy levels and the Auger decay rates of the antiprotonic helium atoms with the coupled rearrangement channel method and the complex-coordinate-rotation method. Calculated transition frequencies were in excellent agreement with observed values. This agreement gives best limit of the antiproton mass with 5×10⁻⁸ uncertainty. This revised version was published online in August 2006 with corrections to the Cover Date.     

On the Question of Spatial Transitions in a System of Atoms

Russian Physics Journal - This paper is a generalization of two of our preceding papers which considered, among other things, a version of the solution with a minimum and a maximum number of atoms...     

Na原子能量自囚禁的加速效应

采用高分辨激光光谱方法，在较高温度条件下，实验观察到Na原子能量自囚禁加剧特征。出现原子加速的光谱行为；并导致零速度原子碰撞转移到高激发态的速度减少。从原子内能碰撞转移的角度，分析了原子速度分布变异的机理。