Raman Spectrum and Intermolecular Forces of the Chlorine Crystal

Abstract

The Raman spectrum of the chlorine crystal has been observed at low temperatures for lattice and intramolecular vibrational regions. The observed spectrum supports the x-ray determined crystal structure Cmca with two molecules in a unit cell, with which the lattice vibrational Raman lines have been assigned. Normal-coordinate calculations showed that the central force field is inadequate for the chlorine crystal and noncentral forces must be taken into account to reproduce the observed frequencies. The force constants obtained based on a central and noncentral force field indicated the importance of charge-transfer interaction in the crystal.