FAR-INFRARED SPECTRA OF CRYSTALLINE ANTIMONY TRI-IODIDE AND ARSENIC TRI-IODIDE

Far-infrared spectra of SbI3 and AsI3 in both single crystal and powder form at 20 K are reported. Principal features are identified through the predictions of a group theoretical analysis and by comparison with Raman data. Tentative assignments of the six infrared active modes are proposed. Certain anomalies are attributed to a partial breakdown of the molecular interpretation of the spectra and to the importance of interionic effects, especially for SbI3.