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Humboldt-Universität zu Berlin - Faculty of Mathematics and Natural Sciences - Optical Systems

Humboldt-Universität zu Berlin | Faculty of Mathematics and Natural Sciences | Department of Physics | Optical Systems | Publications | Molecular emission in laser-induced breakdown spectroscopy: An investigation of its suitability for chlorine quantification on Mars

David Vogt, Kristin Rammelkamp, Susanne Schröder, and H.-W. Hübers (2017)

Molecular emission in laser-induced breakdown spectroscopy: An investigation of its suitability for chlorine quantification on Mars

Icarus(302):470–482.

The intensity of the molecular CaCl emission in LIBS spectra is examined in order to evaluate its suitability for the detection of chlorine in a Martian environment. Various mixtures resembling Martian targets with varying Cl content are investigated under simulated Martian conditions. The reactions leading to the formation of CaCl are modeled based on reaction kinetics and are used to fit the measured CaCl band intensities. MgCl bands are also investigated as potential alternatives to CaCl, but no MgCl bands can be identified in samples containing both Mg and Cl. The study confirms that CaCl is well suited for the indirect detection of chlorine, but finds a strong dependence on the concentrations of Ca and Cl in the sample. Spectra from samples with a high chlorine concentration can have low-intensity CaCl emission due to a deficiency of Ca. A qualitative estimate of the sample composition is possible based on the ratio of the band intensity of CaCl to the intensity of Ca emission lines. Time-resolved measurements show that the CaCl concentration in the plasma is highest after about 1 µs.

ChemCam, LIBS, Molecular LIBS, Chlor, Molekülbande, CaCl, Mars