Infrared spectra and band strengths of CH3SH, an interstellar molecule

Abstract

Three solid phases of CH₃SH (methanethiol or methyl mercaptan) have been prepared and their mid-infrared spectra recorded at 10–110 K, with an emphasis on the 17–100 K region. Refractive indices have been measured at two temperatures and used to estimate ice densities and infrared band strengths. Vapor pressures for the two crystalline phases of CH₃SH at 110 K are estimated. The behavior of amorphous CH₃SH on warming is presented and discussed in terms of Ostwald's step rule. Comparisons to CH₃OH under similar conditions are made, and some inconsistencies and ambiguities in the CH₃SH literature are examined and corrected.