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.

Raman Scattering Studies of Solid-Phase Species

“…These results are in reasonably good agreement with those of Cahill and Leroi (Ref. 15) who determined the band positions to be 1,277 and 1,385 cm-i respectively. It is to be noted that these two intramolecular vibrational Raman bands correspond to Stokes scattering processes involving the lowest-lying Fermi-resonance doublet of CO2.…”

“…As shown by Cahill and Leroi (Ref. 15), CO2 crystallizes in a facecentered-cubic (FCC) lattice structure, and the corresponding space group is Pa3 (T~); a description of the Hermann-Mauguin and Schoenflies space group nomenclature is given in Ref. 16.…”

Metal nanostructure growth on molecular buffer layers of CO2

“…This compares to 6.9 meV for diffusion on Xe [8]. At 88 K, there are three major phonon modes active with energies of 9.05, 11.2, and 16.2 meV with relative intensities of 100, 24, and 10, respectively [23]. E MN agrees very well with the energies of the most prominent phonons, demonstrating the key role that phonons play in diffusion on CO 2 .…”

Raman spectroscopy of supersonic jets of CO2: Density, condensation, and translational, rotational, and vibrational temperatures

“…A search for the crystalline phase of CO 2 in expansions I-IV has been carried out in the region of the strong E g librational mode 73,74 at 73.5 cm Ϫ1 , and in the region of the upper component of the main Fermi diad, 75 at 1384.0 cm Ϫ1 . No evidence of cystalline CO 2 has been found.…”