The resonance Raman spectrum of azulene

Excitation profiles have been measured for three Raman lines of azulene in CS₂ solution in the spectral range of the visible absorption system, viz. 665—570 nm. The results are unexpected in as much as the excitation profiles do not exhibit maxima at or near the absorption peaks. The results are interpreted on the basis of contributions to the A-term by other modes than the one studied in the Raman effect. These terms give rise to interferences which lower the excitation profile in some regions while causing maxima at other frequencies.