Chlorine and fluorine play an important role in the geological history of Mars due to their high concentration in Martian magmas and their influence on the generation and evolution of Martian basalts. Chlorine-bearing salts could also facilitate the formation of eutectic brines that could be important for the fluvial history of Mars. The LIBS instruments of ChemCam and SuperCam can detect emission lines of Cl and F, but the intensity of these emission lines is comparatively low, making it difficult to quantify them correctly. A promising alternative is the quantification by molecular emission of diatomic molecules like CaCl and CaF, which can be observed as intense molecular bands in LIBS spectra if Ca is also present. However, the nonlinear dependence of the band intensity on the concentrations of both elements needs to be considered. In this study, we expand upon our previous analysis of molecular bands by investigating samples which produce CaCl bands, CaF bands, or both. We find that the highest CaCl band intensities are found in samples containing more Ca than Cl, while the strongest CaF bands are found in samples with roughly equal concentrations of Ca and F. Both observations can Preprint submitted to IcarusJune 20, 2019be described by the model that we present here. We also find that the CaCl band is significantly stronger for a sample containing CaCl 2 than it is for a sample containing the same concentrations of Ca and Cl in separate bonds.The opposite is true for the CaF band, which is significantly weaker for the sample containing CaF 2 bonds than it is for the sample that does not contain CaF 2 bonds. These matrix effects are partially attributed to fragmentation during the ablation process and differences in the dissociation energies. Furthermore, we observe that CaF formation is not affected by competing CaCl formation, while CaCl is strongly affected by competing CaF formation. All measurements are done in simulated Martian atmospheric conditions in order to assist the analysis of Martian LIBS data.

Laser‐induced breakdown spectroscopy (LIBS) and Raman spectroscopy are powerful key techniques for the geoanalytical exploration of extraterrestrial bodies, especially when combined. Their data are complementary, which motivates the question of how it can be best combined to maximize the scientific output. For this study, LIBS and Raman data from pure sulfates and their mixtures as well as from other Mars‐relevant salts such as carbonates, chlorides, perchlorates, and sulfates in a basaltic matrix were measured and investigated. All measurements were performed with miniaturized setups, and LIBS experiments were done in simulated Martian atmospheric conditions. Multivariate data analysis (MVA) techniques such as principal component analysis (PCA) and partial least squares discriminant analysis (PLS‐DA) were employed to evaluate the potential for identifying the sulfates or the salts in the basalt with LIBS and Raman data alone and with their low‐level fused data. We found that low‐level data fusion, that is, combination of LIBS and Raman spectra at the data level, can improve the identification of sulfates and salts. Although the approach of low‐level data fusion aims to use all relevant information from both techniques, we observed that not all benefits from the single models are completely represented by the fused model. The computation and performance of appropriate MVA models are affected by the weighting of the single spectra in the combined one, by the dimensionality of the MVA models, and in case of PLS‐DA, by the given input data. From this study, we conclude that generally, data fusion of LIBS and Raman is an advantage for the identification of unknown samples but that more levels, especially, high‐level data fusion (decision level), should be further investigated.

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This thesis investigates the application of laser-induced breakdown spectroscopy (LIBS) with detection in the vacuum ultraviolet (VUV) spectral range for in-situ space exploration. LIBS is a type of optical emission spectroscopy (OES). For LIBS, a pulsed laser is tightly focused onto the sample, thereby ablating material and exciting a luminous plasma. The atoms and ions contained in the plasma radiate light of characteristic wavelengths, which can be analysed with spectrometers like in other types of OES. The spectral analysis allows to identify the chemical elements in the plasma, which are assumed to be representative for the elements in the sample. With LIBS, in principle all elements can be detected. However, especially the non-metal elements are challenging to detect because their strongest lines are located in the VUV spectral range, i.e. below 200 nm, which is often not investigated. Detection in this range brings its own challenges, since large parts of the radiation spectrum are absorbed by the atmosphere surrounding the sample. On celestial bodies without an atmosphere, such as the Moon, the ambient conditions are well suited for VUV-LIBS analyses. In such a scenario, a better detectability for the otherwise challenging elements C, Cl, H, N, O, P and S is expected compared to LIBS in the usually employed detection range above 200 nm.Motivated by the recent ambitions of the national space agencies to return to the Moon and to potentially set up a permanent moon base in the near future, I investigated the potential of VUV-LIBS in a lunar context. For this project, a dedicated set-up for VUV-LIBS was designed and built at Institut für Optische Sensorsysteme of Deutsches Zentrum für Luft-und Raumfahrt (DLR-OS) in Berlin-Adlershof. After an initial characterization including a relative spectral sensitivity estimate, chemically simple samples have been studied in order to identify emission lines that are typically detectable with this set-up. From these measurements, emission lines from Al,

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