Raman Spectrum of Polycrystalline Methyl Bromide

The Raman spectrum of polycrystalline methyl bromide has been observed at 77°K. Two Raman bands at 585 and 594 cm—1 of ν3 were characteristic of rapidly cooled samples. The band at 585 cm—1 disappeared from samples slowly cooled or subjected to warming and cooling several times. The origin of the 585‐cm—1 band is discussed and ascribed to the supercooled crystal or to the amorphous solid. Only the intramolecular fundamental ν5 has been observed to split due to the crystal field.Four lattice vibrational frequencies have been obtained and their tentative assignments are presented.