Polarized Raman spectra of a single crystal of iodine

Polarized and depolarized Raman spectra from an oriented single crystal of iodine at ambient temperature and pressure have been obtained using a micro-Raman apparatus. Temperature of the samples, which turn out to be heated by the laser beam, is monitored through an analysis of the Stokes/anti-Stokes ratio. An accurate analysis of the intensities of the two intramolecular stretching modes as a function of the angle formed by the polarization of the incident beam and the crystallographic axes is reported. The analysis assigns unambiguously the higher frequency band at 189 cm(-1) to the B-3g stretching mode and the lower frequency band at 180 cm(-1) to the A(g) stretching mode. Values for the relevant components of the Raman tensor are also derived and compared to the predictions of a simple bond polarizability model. (C) 2000 Elsevier Science B.V. All rights reserved.