Measurement of Solvent Shifts by Raman Difference Spectroscopy

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 .