Raman spectroscopy of molecular hydrogen and deuterium dissolved in vitreous silica

Abstract

Earlier Raman studies confirming the molecular dissolution of protium and Geuterium in silica have been extended to include room-temperature measurements of the vibra ional-rotational Raman bands and the temperature dependence (11-800 K) of the $Q$ bands. Observation of the $S$ bands provides evidence for ${\mathrm{H}}_2$ and ${\mathrm{D}}_2$ molecular rotation in vitreous silica. The temperature and isotope dependence of the $Q$-band frequency shifts are found to agree with predictions of a solubility model based on a single molecule in a small confining interstice. The origin and temperature dependence of the $Q$-band line shape are discussed within the context of various models which include inhomogeneous broadening, collisional broadening, and recent theories of motional narrowing.