THE INFLUENCE OF LO-TO SPLITTING ON NU-SO2 EXCITON BANDS IN IR AND ATR SPECTRA OF CRYSTALLINE DIMETHYL SULFONE

The IR and attenuated total reflection (ATR) spectra of polycrystallin e solids and oriented specimens of dimethyl sulphone (CH3)(2)SO2 (DMS) and DMS-d(6) have been measured. Several anomalies are seen in the ra nge of the nu SO2 stretching bands. Among these are the appearance of nu SO2 bands in the ATR spectra outside the contours of those bands in the IR spectra. Another anomaly was found to be in the variations of the nu SO2 band contours and maxima in the IR spectra of oriented spec imens. The experimental data can be explained within the framework of the LO-TO splitting (a difference in frequency of the longitudinal and transverse vibrations). (C) 1997 Elsevier Science B.V.