Infra-red cryogenic studies. Part 1.—Hydrogen halide multimers

Abstract

Infra-red spectra are reported of HCl, HBr and HI in argon and other matrices at 20 K. Studies have been made over a wide concentration range from matrix/absorber ratio 2000 to 50 which, together with diffusion (“warm-up”) experiments, enable an interpretation to be offered of the complex pattern of frequencies. The first two intense association bands which arise are assigned to cyclic dimers and trimers respectively. Bands are also assigned to various multimeric species and the frequencies compare favourably with values calculated on the basis of a model based on that proposed by Keyser and Robinson.