Thermal decomposition of dichlorosilane investigated by pulsed laser powered homogeneous pyrolysis

Results of the SF₄ sensitized infrared pulsed laser powered homogeneous pyrolysis of dichlorosilane are reported. Pyrolyses at temperatures of 1350 to 1700 K and pressures of 150 to 230 Torr with reaction times around 7 μs were carried out in the presence and absence of molecules that could potentially scavenge the primary decomposition products (SiHCl and/or SiCl₂). We were unable to irreversibly trap the reaction products, but obtained upper limits for the unimolecular decomposition rate constant under these conditions by measuring reactant loss. The observed rates are consistent with the high activation energy for dichlorosilane decomposition, near 75 kcal/mol, that is predicted by ab initio calculations.