Regularities of Line Strengths in Spectra of NI, FI, and NeII

Recently experimentally determined individual (fine structure) line strengths for the spectra of NI, FI, and NeII are analysed, searching for regularities resulting from similarities in the structure of these species. Strengths of spectral lines of the prominent 3s-3p and 3p-3d transition arrays are investigated. The absolute scales of these experimentally derived data are based on independently determined lifetimes for excited levels of NI, FI, and NeII. The simple Coulomb approximation method was applied for calculations of the matrix elements for the "jumping" electron in order to obtain an average trend in line strengths of the studied emitters. In the case of the isoelectronic species (FI, NeII), additionally the trend resulting from the perturbation theory is taken for comparison. Except the trend study of the absolute scale, the strengths of individual lines within analogous multiplets (in a relative scale) are investigated and compared with data resulting from LS coupling scheme and with semi-empirical calculations.