INFRARED CHARACTERIZATION OF INTERACTIONS BETWEEN DIHYDROGEN AND ALKALI-HALIDES IN ARGON MATRICES - EVIDENCE FOR A DOMINANT ANION INTERACTION

Dihydrogen has been codeposited with alkali halides in argon matrices at similar to 10 K. The presence of the alkali halide induces infrared activity which is assigned to the H-H stretching vibration that is re d-shifted by as much as 114 cm(-1) from the position of the Q branch v ibration of o-H-2 in argon. The observations suggest that it is the an ion of the alkali halide ion pair which is responsible for the perturb ation of H-2. Thus, the largest perturbations have been recorded for K F and CsF while the perturbation due to RbNO3 is not nearly as great a s that for RbCl. Moreover, the position of the perturbed H-H stretch i s quite insensitive to the size of the cation in the series of all;ali chlorides. The extent of perturbation on the H-H stretch has been fou nd to be greater for alkali halide monomers than for aggregates.