The application of Raman difference spectroscopy for the determination of the small frequency shifts arising from solvent effects has been demonstrated. Data are presented for benzene-carbon disulfide, benzene-pyridine, and acetone-chloroform mixtures. The majority of the solvent shifts measured are less than 1.0 cm−1 and these can generally be determined with better than 10% accuracy using a rotating two-compartment liquid cell. The smallest shift measured in this work was 0.06 cm−1. While statistical analysis indicates that uncertainties as small as ±0.01 cm−1 can be obtained in many cases, artifacts may cause apparent shifts up to ±0.03 cm−1.
