ISOLATION OF PRERESONANCE AND OUT-OF-PHASE DUAL CIRCULAR-POLARIZATIONRAMAN OPTICAL-ACTIVITY

We report the first isolation of preresonance Raman scattering behavio r in Raman optical activity (ROA) and the first measurement of out-of- phase dual circular polarization (DCP(II)) ROA. Using a series of mole cules of increasing delocalized electronic structure, we observe a cor related increase in the degree to which the DCP(I) and ICP(u) ROA back scattering spectra differ from one another. Through this comparison, R OA is shown to be a sensitive way of detecting the presence of prereso nance Raman scattering intensity using a single Raman excitation wavel ength.