Theory of resonance Raman optical activity: the single electronic state limit

Abstract

The theory of natural Raman optical activity (ROA) is extended to the limit of strong resonance with a single electronic state (SES). It is shown that in the SES limit, the resonance ROA (RROA) bands all have the same sign, and their relative intensities are identical to the corresponding resonance Raman (RR) parent bands. The sign of the RROA bands are predicted to be opposite that of the pure electronic circular dichroism (CD) of the single, resonant electronic transition. The ratio of the RROA to the RR spectrum is the same or one-half the magnitude of the electronic CD anisotropy ratio of the resonant electronic state. Deviation from this simple pattern is indicative of contributions from more than one excited electronic state to the RR and RROA spectra, and hence is a sensitive probe of the electronic origin of ordinary RR spectra.