等离子体屏蔽效应对Ar^(16+)基态和激发态能级的影响

Influence of plasma shielding effect on ground state and excited state energies of Ar^(16+)

基于Rayleigh-Ritz变分原理,发展了一套处理弱耦合等离子体环境中多电子原子(离子)非相对论能量及其相对论修正的解析方法.通过考虑电子间交换相互作用以及内外壳层电子的屏蔽效应,计算了Ar^(16+)基态1s^2~1S、单激发态1sns^(1,3)S (n=2—5), 1snp^(1,3)P (n=2—5)和双激发态2snp^1P (n=2—5)非相对论能量及其相对论修正值(包括质量修正、单体和双体达尔文修正以及自旋-自旋接触相互作用项),讨论了等离子体屏蔽效应对能级的影响.结果表明:相对论质量修正和第一类达尔文修正占主导,比其他相对论修正项高出三个数量级.此外,等离子体屏蔽效应具有明显的态选择性,屏蔽效应对外壳层电子的影响大于内壳层电子,随着等离子体屏蔽参数的增加,外壳层电子轨道向外延展,激发态越高,延展程度越大.

A systematical knowledge of the atomic properties in plasma is of great interest for various research areas,such as the explanation of the X-ray radiation from universe, plasma diagnostics, extreme ultraviolet(EUV)and X-ray sources and so on. Among these researches, the detailed information about how the plasma influences the atomic energy level and transition spectrum are crucial for understanding the X-ray emission mechanism and the state of plasma. An analytic calculation method of treating the non-relativistic energy and its relativistic corrections for the multi-electron atoms embedded in weakly coupled plasma is developed based on the Rayleigh-Ritz variation method. The systematical investigations are performed for the ground state 1 s21 S,single excited states 1 sns1,2 S(n = 2-5), 1 snp1,3 P(n = 2-5) and double excited state 2 s2 p 1 P of Ar16+ ion in weak coupled plasma. The analytic formulas for calculating the non-relativistic energy and its relativistic correction energy are derived, which include mass correction, one and two-body Darwin correction, spin-spin contact interaction and orbit-orbit interaction. All the angular integration spin sums involved in the problem are worked out explicitly by using the irreducible theory. The influence of plasma on non-relativistic energy and relativistic correction energy are discussed. The results show that the mass correction and the one-body Darwin correction are the main ones among the terms of relativistic correction, and are three orders of magnitude greater than the other relativistic terms. The plasma shielding effect mainly affects the non-relativistic energy,and has little effect on the relativistic correction. At the same time, it has a more significant selectivity for the electronic configuration. Further research shows that the influence of plasma on the energy of the outer shell electron is greater than that of the inner shell electron. With the increase of the plasma shielding parameters,the outer shell electron extends outward, and the higher the excited state, the greater the degree of extension is.This work should be useful for astrophysical applications where such a plasma environment exists.