Xe~(53+)离子与Xe原子碰撞过程中的辐射电子俘获和辐射退激发光谱的理论研究

基于多组态Dirac-Fock方法和密度矩阵理论,系统地研究了在197 Me V/u的碰撞能量下,Xe~(53+)离子与Xe原子的辐射电子俘获过程(REC)以及电子被俘获到激发态后辐射退激发产生的特征谱线.计算了炮弹Xe~(53+)离子俘获电子到不同壳层np_(1/2,3/2)(n=2—5)的总截面与相应的REC光子能量和角分布,以及由激发组态1snp_(1/2,3/2)(n=2—5)J_f=1向基态1s~2Jd=0辐射退激发的跃迁能量、跃迁概率和特征光子的角分布和线性极化度.计算结果表明,辐射光子具有显著的角各向异性特征.此外,1snp_(3/2)J_f=1→1s~2J_d=0退激发特征光子也显示出很强的线性极化和角各向异性特征,而1snp_(1/2)J_f=1→1s~2J_d=0退激发特征光子的线性极化度趋于零并且角分布也趋于各向同性.

Theoretical studies on the radiative electron capture and subsequent radiative decay in the collision of Xe53+ ions with neutral Xe

The radiative electron capture (REC) and subsequent radiative decay of initial hydrogen-like Xe⁵²⁺ ions are studied in the collision of Xe⁵³⁺ with Xe atom at a projectile energy of 197 MeV/u within the framework of the multiconfiguration Dirac-Fock method and the density matrix theory. We calculate the differential and total cross sections as well as the REC photon energies for REC to the 1snp_{1/2, 3/2} J_f=1 (n=2-5) levels of finally helium-like Xe⁵³⁺ ions. Moreover, the transition energies and rates of the subsequent 1snp_3/2 J_f=1→ 1s² J_d = 0 decay as well as the angular distribution and linear polarization of the associated characteristic photons are also calculated. It is found that the REC photons are remarkably anisotropic. Through the analysis of the REC angular distribution characteristics, we find that the different configurations of the REC angular distribution are similar in quality, and they all have a peak at the 90°. That is to say, the REC process can more easily occur in the direction perpendicular to the incident direction of the projectile ions. In addition, while the characteristic photons from the subsequent 1snp_3/2 J_f=1→1s² J_d= 0 radiative decay of Xe⁵²⁺ ions exhibit an anisotropic angular distribution and strong linear polarization, their counterparts from the 1snp_1/2 J_f = 1→ 1s² J_d = 0 decay are almost isotropic and linearly unpolarized. The angular distribution and linear polarization of the radiation photon decay from the (1s np_1/2,3/2 J_f = 0) states to the ground state（1s² J_d = 0）both reach a maximum value at the 90°, their characteristics are similar to those of the REC photons, that is to say, the deexcited process can more easily occur in the direction perpendicular to the incident direction of the projectile ions, and in this direction the decay photons have much larger polarization degree.