Investigation of MgCl, MgF, CaCl and CaF emission in LIBS for the quantification of chlorine and fluorine in Martian atmospheric conditions

Abstract

Laser-Induced Breakdown Spectroscopy (LIBS) is an increasingly important tool in the exploration of Mars. The detection of Cl and F with LIBS has been a challenge due to their low-intensity emission lines. The detection via molecular emissions has been proposed as a way to enhance the level of detection for halogens. In this study, the suitability of molecular emissions of CaCl, CaF, MgCl, and MgF in LIBS spectra for the detection and quantification of Cl and F is investigated. Experiments are made in simulated Martian ambient conditions and numerical simulations are used to explain the observations. The CaCl and CaF emissions can lead to an improved detection while MgCl and MgF emissions are very weak and do not improve the limit of detection for these Cl and F.