High resolution Raman spectra of the Fermi diad in crystalline CO2 at 6 K

Abstract
High resolution Raman spectra of the Fermi diad ω1:2ω2 in crystalline CO2 at 6 K were obtained by means of a tandem interferometer‐spectrometer instrument. For the first time the two components of the factor group splitting of the Ω hybrid level were perfectly resolved. The bandshape of the two overlapping components of the Ω+ state were obtained by means of polarization measurements. The very different residual bandwidths of these crystal modes are discussed in terms of decay processes involving the two‐phonon continuum and the isotopic impurity levels.