Molecular emissions in the laser-induced plasma in simulated Martian conditions - calibration models and new insights from plasma imaging

Abstract

Molecular emissions in LIBS can be used to detect elements that do not have strong emission lines, such as Cl and F. This is interesting for Martian exploration, where Cl and F offer important clues about past environments. In this study, we investigate the relationship between the reactant concentrations and the intensities of the molecular emissions of MgCl, CaCl, and CaF. The intensities of CaCl and CaF emissions are well-described by the non-equilibrium calibration model that is introduced. Plasma imaging experiments show that the molecules only form close to the center, suggesting that the plasma temperature is unexpectedly low there, potentially due to rarefaction and radiative losses.