Temperature-dependent, VIS-NIR reflectance spectroscopy of sodium sulfates

Hydrated sodium sulfates have been suggested to be present in variable amounts Solar System objects such as Mars and Europa, among the possible others. The presence of these hydrated species is related current/past aqueous environments, thus has an importance regarding potential habitability planetary objects. In this study, we analyzed anhydrous sulfate (thénardite) (mirabilite) by means visible-infrared reflectance spectroscopy 0.4–5 ?m spectral range, at different low temperatures between 80 298 K. Each mineral three grain sizes, 36 150 ?m. compound, thénardite, characterized a nearly flat spectrum visible near IR up 2.6 ?m, while 3–4 region, shows few weak features due H2O SO42? overtones/combinations. first strong overtone 4.6 Spectra mirabilite are substantially absorption 1–3 overtone/combination bands occurring 3.8 4.7 A feature appearing 2.18 also putatively attributed ion. show changes function temperature. hydration strongest dependence with temperature, both terms shift position change shape. Bands 3.1–3.24 well located 1.78 2.47 mirabilite, could used diagnostic proxies for detection two minerals on bodies.