Standoff mid-infrared reflectance spectroscopy using quantum cascade laser for mineral identification

Mid-Infrared Reflectance Spectroscopy Based on External Cavity Quantum Cascade Lasers for Mineral Characterization

“…The spectra measured on different minerals were presented in a previous work and compared to the ASTER database. 14,21 For reference, figures in the Supplemental Material present the ECQCL spectra and their associated ASTER spectra for k-feldspar, albite, muscovite, biotite, chlorite, calcite, dolomite, gypsum, anhydrite, pyrite, and chalcopyrite. In each case, the ECQCL average spectrum generally exhibited the same peak spectral positions and shape as their ASTER references.…”

“…Previous ECQCL-based MIR data analysis showed that the multivariate curve resolution (MCR) method could extract individual endmembers of mineral mixture in a half-core sample. 14 In the present work, we measured 70 locations on a polished rock tile that has been also measured using quantitative mineral analysis (QMA) based on scanning electron microscope energy dispersive spectroscopy (SEM-EDS). Only the diffusely scattered light is measured at a collection angle of 20° from the surface normal while the specular reflected light from the polished tile surface is suppressed.…”

“…13 Preliminary results of mineral identification were shown for silicates and carbonates. 14 Mid-infrared spectroscopy is particularly suited for mineral identification by probing the fundamental vibrational bands of crystals, instead of the overtones or the impurities captured in the visible and the near infrared spectral regions, hence providing distinct spectral signatures. ECQCL-based reflectance spectroscopy was also combined to laser-induced breakdown spectroscopy for mineral identification and quantification.…”