Stark halfwidth trends along the homologous sequence of doubly ionized noble gases

Abstract

Aims. The aim of this work is to analyse experimental Stark halfwidths behaviour for the ( 3 P)ns−( 3 P)np and ( 3 P)np−( 3 P)nd transitions along the homologous sequence of single ionized noble gases. This kind of trend analysis can be useful for Stark halfwidths predictions and therefore for spectroscopic diagnostic of astrophysical plasmas. Methods. The compilation of Stark halfwidths was done taking into account the measurements developed in the last decades. The experimental results and observed Stark halfwidth trends for different multiplets of ionized noble gases were compared with the modified semiempirical formula (MSE) calculations and other theoretical estimations. Results. The analysis shows that the halfwidths of the spectral lines in all observed multiplets belonging to the same transitions have a similar trend along the homologous sequence. Stark halfwidths of ( 3 P)ns−( 3 P)np transitions are more or less constant, while those of ( 3 P)np−( 3 P)nd transitions have a clear increasing slope. A qualitative explanation of the observed Stark halfwidth trends based on the energy level structure is also given.