QUANTITATIVE COMPARISON OF EXPERIMENTAL INFRARED AND RAMAN OPTICAL-ACTIVITY SPECTRA

Infrared vibrational circular dichroism (VCD) and vibrational Raman op tical activity (ROA) have been measured and compared quantitatively ov er the frequency range from 835 to 1345 cm(-1) for trans-pinane, cis-p inane, alpha-pinene, and beta-pinene. For these molecules in this regi on of spectral overlap between VCD and ROA, the average ratio of VCD o r ROA to its parent vibrational intensity favors ROA by a factor of tw o to three. Several vibrational modes in each molecule yield both larg e VCD and large ROA, while several other modes show little propensity toward significant VCD or ROA intensity. Beyond this general property of a few strongly chiral and strongly achiral vibrational modes, littl e additional correlation between VCD and ROA intensity is found. This quantitative compilation of VCD, infrared, ROA, and Raman intensities provides an experimental basis for computational intensity studies of VCD, ROA, and their theoretical comparison.