Resonance raman excitation profiles of CrO2−4 from K2CrO4/K2SO4 lyophilised solid mixtures

Raman excitation profiles for the chromate 863 cm−1 totally symmetric mode and for its first two overtones, measured in rigorous resonance with the absorption band at 372 nm, are reported. Data were taken on a lyophilised mixture of K2CrO4 in K2SO4, and the 981 cm−1 sulphate fundamental was used as an internal standard for intensity measurements. Results are analysed in terms of a model based on the Franck-Condon scattering mechanism assuming either a singlet F2 resonant state or three non-degenerate states resulting from the Cs symmetry of the CrO2−4 ion in our medium. Comparisons are made with the results obtained by other authors for the isoelectronic MnO−4 ion.