The Infrared Spectra of Oriented Rhombic Sulfur Crystals with Polarized Radiation

Abstract

The infrared spectra, in the rock salt region, of oriented sections of single rhombic sulfur crystal have been obtained. The spectra of sections perpendicular to the c axis of the crystal, the 001 type planes, have been compared, under ordinary radiation with those of sections parallel to the c axis, 110 type planes. Most bands in the region investigated, 700 to 1500 cm⁻¹, show differences in intensity in the two spectra. With a 110 section and radiation polarized at various angles, similar changes in intensity were observed. Both experiments lead to similar conclusions regarding the direction of the oscillating dipole in the vibrations giving rise to the observed bands. Assignments of the infrared active species (B₂ or E₁) in these bands are given but no attempt is made to explain them in terms of the fundamental vibrations.