Abstract
The Raman spectrum of polycrystalline methyl iodide has been studied at 77° and 195°K, and the difference between the Raman and infrared spectra has been discussed. All of six frequencies due to lattice vibrations have been found, and their assignments have been given. The heat capacity of crystalline methyl iodide at various temperatures has been calculated from the spectral data obtained and compared with the observed values of crystalline methyl bromide.