Temperature-dependent resonance Raman profiles of β-carotene in carbon disulfide

Abstract

Resonance Raman (RR) profiles of the 1005, 1155, and 1525 cm−1 modes of β-carotene dissolved in carbon disulfide have been measured at room temperature and at 172 K. Previous studies, based upon room temperature measurements, have indicated that inhomogeneous (i.e., site) broadening may be important for this system. Our measurements are the first RR data for this system at two temperatures. Such data are necessary in order to study the relative importance of inhomogeneous broadening and thermal broadening. Using previously developed transform techniques, we analyze our RR data by calculating profile line shapes directly from our measured optical absorption data for each temperature. The assumptions underlying this analysis do not include inhomogeneous broadening, and the calculations yield profile line shapes which are in quite good overall agreement with the measured profile line shapes for all three modes at both temperatures. We have also extended the transform calculations in order to incorporate inhomogeneous broadening. However, the agreement between the measured and calculated RR profile line shapes is not substantially improved by the inclusion of inhomogeneous broadening in the transform analysis.