Photolysis of hydrogen and fluorine in solid argon. Matrix infrared spectra of (HF)₂, (HF) (DF), and (DF)₂

Argon diluted samples of H₂ and F₂ were codeposited at 10 K, and little reaction was observed. Photolysis produced a strong new 3826 cm^-1 band, in agreement with assignment to (HF)₂ from HF codeposition experiments, weak HF monomer and trimer bands, and a sharp new 3930 cm^-1 band for the H-F intermediate species. Sample annealing markedly increased trimer, relative to dimer and monomer, and destroyed the intermediate species. Similar experiments were done with D₂ and HD; the latter gave a strong 2808 cm^-1 absorption for the more stable (HF) (DF) mixed dimer and a weak 3832 cm^-1 band for the less stable (DF) (HF) mixed dimer. The ability of the argon matrix cage to quench substantial reaction exothermicity is demonstrated by the preferential stabilization of (HF)₂ in these experiments.