Crystal Vibrations and Intermodular Interactions of CH3X and CD3X (X=Cl, Br, and I)

Abstract

Abstract Normal coordinate treatments of the crystal vibrations of methyl chloride, methyl bromide, methyl iodide, and their perdeuterated analogs have been made. The values of force constants of non-bonded atom interactions have been determined so as to give the best fit to the lattice frequencies and the splitting frequencies of the intramolecular vibrations. It has been found that the dipole-dipole interactions are essential to account for the splittings of some internal modes, but their effects on lattice frequencies are negligible.