EFFECTS OF SOLVENT ON THE EXCITATION PROFILE OF THE NU-2 LINE OF BETA-CAROTENE

The excitation profile of the v2 line of β-carotene has been examined as to its solvent dependency. Excitation profiles in acetone, cyclohexane, ethyl alcohol, and toluene show that the origin of the v 2 line in the resonance Raman spectrum is a vibronic coupling with the 0-0 and 2-0 virtual transitions of a single electronic state, presumably the excited π* state. The solvent shifts in the excitation profile correlate with the observed solvent shifts in the visible spectrum. It is shown that solvents can cause large perturbations to the intensity of the v 2 line. © 1980 American Institute of Physics.