Neutral lithium spectral line 460.28 nm with forbidden component for low temperature plasma diagnostics of laser-induced plasma

Abstract

We present the results of theoretical and experimental line shape study of the Li I 460.28nm line with a forbidden component in a low temperature laser-induced plasma. For this purpose a computer simulation method is used to calculate the overall line profile in the electron number density range of (0.5–11.0)×1016cm-3 and the electron temperature 5800K. The same computer simulation method is used to evaluate asymmetric profiles of the isolated Li I 497.17nm line in the same electron density range and for several electron temperatures between 3500K and 10300K. The results for the Li I isolated line are used together with two other theoretical calculations for independent electron density measurements in laser induced plasma. The electron temperatures in the range of 4000–7000K were determined from relative Li I line intensities using Boltzmann plot technique. The comparison between calculated profiles and experimental data for the Li I 460.28nm line with a forbidden component indicates that theoretical results can be used for electron density diagnostics in the aforementioned density range with an accuracy of ±10–15%. To facilitate the application of theoretical line profiles simple expressions are supplied.