Matrix-Isolation Study of the Vacuum-Ultraviolet Photolysis of Difluorosilane. The Infrared and Ultraviolet Spectra of the Free Radical SiF2

The vacuum-ultraviolet photolysis of difluorosilane in inert matrices at cryogenic temperatures has been found to lead to the stabilization of an appreciable concentration of SiF2. A system of ultraviolet absorption bands observed in a neon matrix corresponds very well with the 0v2′0–000 bands recently reported for gas-phase SiF2 produced by another technique. In an argon matrix, the bending fundamental of SiF2 appears at 343 cm−1, and the two stretching fundamentals at 843 and at 855 cm−1. Evidence is presented supporting a previous assignment of these two fundamentals to the symmetric and antisymmetric stretching modes, respectively. Carbon monoxide matrix observations indicate that H-atom detachment plays an important role in the photolysis of difluorosilane. There is no evidence for the occurrence of processes involving F-atom detachment. It appears likely that an appreciable concentration of HSiF2 is also stabilized in the present experiments.