in gaseous matrix Kinetics; Irradiation (UV/VIS); laser flash photolysis/laser absorption technique; SiC4H8 (2.5 mTorr) asphotoprecursor of SiH2 (193 nm flash photolysis, 60-80 mJ), at 295 K, t otal pressure 10 Torr (SF6 diluent); not isolated, detd. by UV-spectroscopy;