Lorentz-Lorenz Coefficient of Ice Molecules of Astrophysical Interest: N2, CO2, NH3, CH4, CH3OH, C2H4, and C2H6

Abstract

[EN] This work calculates the Lorentz-Lorenz coefficient with the refractive index and density values of various molecules in their solid phase measured in our laboratory under astrophysical conditions. This was completed for a range of temperatures from 13 K to close to the sublimation temperature for each molecule. The studied molecules were N-2, CO2, NH3, CH4, CH3OH, C2H4, and C2H6. For CO2, our results match those found in the unique similar previous work in the literature. The results obtained for NH3 and CH3OH are relevant because they confirm that the procedure adopted is applicable also to polar molecules. The study presented here updates the previous work on these molecules by focusing on their solid states under astrophysical conditions and at a range of temperatures. The knowledge of the Lorentz-Lorenz coefficient in a specific temperature range allows for calculating the density using only the refractive index