Stand-off laser induced breakdown spectroscopy on meteorites: calibration-free approach

In this work, LIBS (Laser Induced Breakdown Spectroscopy) capability to operate in stand-off configuration, without the need of a direct contact with the sample, has been coupled with the calibration-free (CF) approach to LIBS data analysis. The latter does not require the use of standard calibration. The feasibility of the calibration free method on stand-off LIBS spectra has been thereby tested. The quantitative analysis was performed on samples of two well-known meteorites, Toluca (iron meteorite) and Sahara 98222 (L6 chondrite) by using a stand-off configuration at a distance of 5 m. The plasma temperature and the electron number densities were determined for each sample and for each laser shot in order to apply the CF method. For the Toluca meteorite sample Fe, Ni and Co content was quantified during the depth profile. For the Sahara 98222 major and minor elements (Fe, Mg, Si, Na, Ti, Al, Cr, Mn, Ca, Ni, Co) were analysed by averaging different meteorite zones because of its strong inhomogeneity. Results demonstrate the possibility of remote analysis of minor bodies and space debris.