Effect of plasma inhomogeneity on the determination of Strark broadening coefficients by Laser-Induced Breakdown Spectroscopy

Laser-Induced Breakdown Spectroscopy (LIBS) is increasingly used for the determination of fundamental spectroscopic parameters (transition probabilities and Stark broadening coefficients) of many emission lines of several elements. In this paper, the effect of plasma inhomogeneity on the precision of the determination of the Stark broadening coefficients is discussed, using a simple two-levels model and the solution of the radiative transfer equation. The main result of this work is the evidence that, when the experimental conditions are carefully chosen to limit self-absorption/self-reversal of the emission line, the approximation of homogeneous plasma does not critically affect the validity of the results obtained, thus justifying the use of conventional LIBS experimental set-up for the determination of Stark broadening coefficients.