Abundance determination of atoms and ions in the channel plasma of lightning

Abstract

Based on the multi-configuration Dirac-Fock (MCDF) method, accurate atomic spectral data were calculated and used for plasma spectral diagnostics and line identification. The formation of multiplet emission lines due to the proximity of the upper and lower levels of the transition is common. For multiplet analysis, some software is often used for line separation; however, this is a rather inaccurate process. In this study, the CF-LIBS and Saha-Boltzmann methods for multiplet emission lines are derived, which allow the use of multiplet and singlet emission lines. This CF-LIBS and Saha-Boltzmann method for multiplet is used in lightning plasma spectroscopy for obtaining particle abundances in the lightning channel. It was found that there is a dependence between the intercept, ξ, of the Boltzmann plot and the ionic abundance, η, of the plasma, and that the differences in η in different particles are attributed to the varying amounts of nitrogen and oxygen in the air. Then, the final measured η-data indicate that N II ions are the most abundant in this lightning, with N III and O III ions being extremely rare. The presently reported data are in better agreement with some verification data and other measurements.