Raman excitation profiles of actinomycin D

Pre-resonance Raman spectra of actinomycin D have been measured using the exciting lines of an Ar+ laser. The analysis of the excitation profiles provided information on the origin of the electronic states; in particular, the absorption feature between 400 and 500 nm was interpreted as due to a vibrational structure of a single electronic state which is located at 450 nm. In addition, on the basis of the excitation profiles, the number of observed Raman bands, and their frequencies, it has been possible to propose a vibrational assignment of the chromophoric framework of the drug.