 The infrared multiphoton dissociation of trichlorosilane (HSiCl3) also yields polysilicon dichloride, (SiCl2)n, along with HCl.SiBr4 and SiI4 react with Si at high temperatures to produce SiBr2 and SiI2, which polymerize on quenching.The polysilicon dihalides are generally stable under vacuum up to about 150-200°C, after which they decompose to perhalosilanes, Sin"X"2n+2 (where n = 1 to 14), and to polysilicon monohalides.