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Highlights: What are the main findings? Atomic spectroscopy for Ar7+, Kr7+, Xe7+, and Rn7+ ions with high accuracy. Plasma screened ionization potential, atomic transition amplitudes and rates. Ionisation potential depression parameters. What is the implication of the main finding? Properties of the astrophysical medium. Properties of laboratory plasma. The growing interest in atomic structures of moderately stripped alkali-like ions in the diagnostic study and modeling of astrophysical and laboratory plasma makes an accurate many-body study of atomic properties inevitable. This work presents transition line parameters in the absence or presence of plasma atmosphere for astrophysically important candidates Ar7+, Kr7+, Xe7+, and Rn7+. We employ relativistic coupled-cluster (RCC) theory, a well-known correlation exhaustive method. In the case of a plasma environment, we use the Debye Model. Our calculations agree with experiments available in the literature for ionization potentials, transition strengths of allowed and forbidden selections, and lifetimes of several low-lying states. The unit ratios of length and velocity forms of transition matrix elements are the critical estimation of the accuracy of the transition data presented here, especially for a few presented for the first time in the literature. We do compare our findings with the available recent theoretical results. Our reported data can be helpful to the astronomer in estimating the density of the plasma environment around the astronomical objects or in the discovery of observational spectra corrected by that environment. The present results should be advantageous in the modeling and diagnostics laboratory plasma, whereas the calculated ionization potential depression parameters reveal important characteristics of atomic structure. [ABSTRACT FROM AUTHOR]

Here, we report on accurate ab initio calculations to study astrophysically important elec- tromagnetic transition parameters among different low-lying states of Sn IV. Our ab initio calculations are based on the sophisticated relativistic coupled cluster theory, which almost exhausts many important electron correlations. To establish the accuracy of the calculations, we compare our results with the available experiments and estimate the transition amplitudes in length and velocity gauged forms. Most of these allowed and forbidden transition wave- lengths lie in the infrared region, and they can be observed in the different cool stellar and interstellar media. For the improvement of uncertainty, we use experimental energies to the estimations of the above transition parameters. The presented data will be helpful to find the abundances of the ion in different astrophysical and laboratory plasma. [ABSTRACT FROM AUTHOR]

In this paper, we report on weighted oscillator strengths of El transitions and transition probabilities of E2 transitions among different low-lying states of triply ionized germanium using highly correlated relativistic coupled cluster (RCC) method. Due to the abundance of Ge IV in the solar system, planetary nebulae, white dwarf stars, etc., the study of such transitions is important from an astrophysical point of view. The weighted oscillator strengths of El transitions are presented in length and velocity gauge forms to check the accuracy of the calculations. We find excellent agreement between calculated and experimental excitation energies. Oscillator strengths of few transitions, wherever studied in the literature via other theoretical and experimental approaches, are compared with our RCC calculations. [ABSTRACT FROM AUTHOR]