THERMAL-DECOMPOSITION OF DICHLOROSILANE INVESTIGATED BY PULSED-LASER POWERED HOMOGENEOUS PYROLYSIS

Results of the SF6 sensitized infrared pulsed laser powered homogeneou s 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 mu s were carried out in the presence and absence of molecul es 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 decompositio n rate constant under these conditions by measuring reactant loss. The observed rates are consistent with the high activation energy for dic hlorosilane decomposition, near 75 kcal/mol, that is predicted by ab i nitio calculations.