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The gas-phase Raman spectrum of CSz has been recorded and analysed in the region of the v1 : 2u2 Fermi resonance. The absolute differential Raman scattering cross-sections and depolarization ratios of the observed vibrational transitions are satisfactorily interpreted in terms of three bond polarizability parameters and the cubic force constant k m .

From an analysis of the photoelectrically recorded Raman band of acetylene at 3950 cm-', which contains contributions from u, +u4 and its hot bands, u3+us in Fermi resonance with u2+u4+2vg, and the Q-branch of 215, some anharmonicity constants were determined. In particular xZ2 = -7.4 cm-' was obtained directly for the first time, other constants are revised due to a more complete consideration of the resonance perturbations. A computer simulation of the u4 fundamental and the u1 +u4 combination band shows excellent agreement with the experimental spectra.

The temperature dependence of the intensities of the Q-branches in the Raman spectrum of gaseous CO2 in the Fermi resonance region was measured in the range from 300 K to 650 K. The intensity contours were reproduced by computer simulation, taking into account energy levels up to ( v1 v21 v3) = (30°0) as final states. Calibration curves are given for the determination of temperatures from the intensity distribution in the hot bands of the Raman spectrum of CO2.

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