Raman Spectra of Solid CO2, N2O, N2, and CO

Abstract

The Raman spectra of solid CO2, N2O, N2, and CO have been observed. Each spectrum can be analyzed by assuming an approximately ordered structure isomorphous with that of CO2. The lattice mode intensities have been calculated on the basis of the oriented gas model; they are in good agreement with the measured values and lead to confident assignments of the observed bands. The frequencies of the Eg and two Tg librations are 73.5, 91.5, and 132 cm−1, respectively, for CO2(15°K) and 68, 82, and 124.5 cm−1, respectively, for N2O (15°K). In α-N2 at 16°K two sharp bands are observed at 33.5 cm−1 (Eg) and 37.5 cm−1 (Tg). The other Tg mode may coincide with the Eg. Only one broad, asymmetric lattice band is observed for α-CO, which is located at 47.5 cm−1 at 12°K. The peak frequencies of these bands decrease an average of ∼ 15% on warming from 15°K to the phase transition, and there is a considerable concommitant increase in their widths.