Relativistic spectroscopy of plasma-embedded Li-like systems with screening effects in two-body Debye potentials

Abstract

The spectroscopic properties of Li atom and Li-like Ca and Ti ions in the plasma environment are investigated using a relativistic coupled-cluster (RCC) method. Assuming the plasma is of low density and very hot, we consider the Debye model with two approximations by accounting the screening effects: (i) in the nuclear potential alone and (ii) in both the nuclear and the electronelectron interaction potentials. First, the calculations for the energies and the lifetimes of the atomic states are carried out for the plasma free systems in order to check their accuracies following which they are investigated in the plasma environment. It is observed that screenings in the electronelectron interaction potentials stabilize the systems more than the case when the screenings present only in the nuclear potential. Similarly, the earlier predicted blue and red shifts in the ∆n = 0 and ∆n = 0 transition lines (with the principal quantum number n) of the Li-like ions change significantly in the case (ii) approximation. The level-crossings among the energy levels are observed for the large screening effects which seem to be prominent in the states of higher orbital angular momentum. The lifetimes of many low-lying states and the relative line-intensities of the allowed transitions are estimated considering different plasma screening strengths.PACS numbers:

Plasma screening effects on the electronic structure of multiply charged Al ions using Debye and ion-sphere models

“…However at very high screening region, this EE starts decreasing at some critical D value in the SD approximation. This behavior was also seen in the hydrogen-like ions [5] and lithium-like ions [42] in the Debye model studies. Where as in the NSD potential approximation, this behavior disappears.…”

New Relativistic Approach to Computing Spectral Parameters of Multicharged Ions in Plasmas

“…In Tables 1 and 2 we list the numerical variations in the lifetimes of the 2p 1/2 , 3s 1/2 , 3p 1/2 , 3d 3/2 , and 4s 1/2 states in Ca XVIII for different µ values. The analysis shows that the presented data are in physically reasonable agreement with the NIST experimental data and theoretical results by relativistic coupled-cluster (RCC) method calculation [3]. However, some difference between the corresponding results can be explained by using different relativistic orbital bases and by difference in the model of accounting for the screening effect as well as some numerical differences..…”

Isotope shift of the 2s 2S1/2 → 2p 2P1/2,3/2 transitions of Li-like Ca ions*

“…It can be found that the wavelengths calculated in present work are in good agreement with the values of previous work. [49][50][51] The consistency of the transition probability from two different gauge is fairly good, which indicate that the wave function used in the present work is good in some extent. It can also be found that the transition probabilities in this work are in good agreement with many-body perturbation theory (MBPT) by Johnson et al and relativistic coupled-cluster method (RCC) by Das et al Although the methods used are different, the electronic correlation effect, Breit interaction and QED correction are almost same.…”