Weak- and hyperfine-interaction-induced 1s2s1S0→ 1s2 1S0E1 transition rates for the isoelectronic sequence of Helike ions have been calculated using the multi-configuration Dirac–Hartree–Fock(MCDHF) and relativistic configuration interaction methods. The results should be helpful for the future experimental investigations of parity non-conservation effects.
基于多组态Dirac-Fock理论方法和冲量近似,对Xe54+与Xe在197 Me V/u碰撞能量下,炮弹离子的俘获及退激发过程进行了理论研究.计算了炮弹离子从中性靶原子俘获一个电子到nl(n=1,2,3,4,5;l=s,p,d)轨道上的辐射电子俘获截面和相应的辐射光子能量,以及俘获末态退激发辐射跃迁的能量和概率.结合这些计算结果,进一步模拟了碰撞产生的炮弹离子的退激发X射线谱的结构,并与兰州重离子加速器装置上的最新实验观测结果进行了比较,符合得很好.
The transition energies and electric dipole(E1)transition rates of the K,L,and M lines in neutral Np have been theoretically determined from the MultiConfiguration Dirac–Fock(MCDF)method.In the calculations,the contributions from Breit interaction and quantum electrodynamics(QED)effects(vacuum polarization and self-energy),as well as nuclear finite mass and volume effects,are taken into account.The calculated transition energies and rates are found to be in good agreement with other experimental and theoretical results.The accuracy of the results is estimated and discussed.Furthermore,we calculated the transition energies of the same lines radiating from the decaying transitions of the K-,L-,and M-shell hole states of Np ions with the charge states Np1+to Np6+for the first time.We found that for a specific line,the corresponding transition energies relating to all the Np ions are almost the same;it means the outermost electrons have a very small influence on the inner-shell transition processes.
Radiation from laser-produced plasmas was examined as a potential wavelength calibration source for spectrographs in the extreme ultraviolet(EUV) region.Specifically, the EUV emission of chromium(Cr) plasmas was acquired via spatiotemporally resolved emission spectroscopy.With the aid of Cowan and flexible atomic code(FAC) structure calculations,and a comparative analysis with the simulated spectra, emission peaks in the 6.5–15.0 nm range were identified as 3 p–4 d, 5 d and 3 p–4 s transition lines from Cr5+–Cr10+ions.A normalized Boltzmann distribution among the excited states and a steady-state collisional-radiative model were assumed for the spectral simulations, and used to estimate the electron temperature and density in the plasma.The results indicate that several relatively isolated emission lines of highly charged ions would be useful for EUV wavelength calibration.
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.
