Measurements of High-Temperature Silane Pyrolysis Using SiH4 IR Emission and SiH2 Laser Absorption

The thermal decomposition of silane highly diluted in argon was observed behind reflected shock waves over the temperature range from 1060 to 1730 K and pressures between 0.6 and 5.0 atm, making this the first SiH4 decomposition study to thoroughly investigate pressures above 1 atm. Silane and silylene time histories were monitored using the infrared emission of SiH4 near 4.7 μm and laser absorption of a SiH2 A−X transition near 579 nm. Reaction rate coefficients for the first- and second-order forms of the decomposition reaction SiH4 + M = SiH2 + H2 + M were determined from the species measurements for M = Ar. The effects of competing reactions were considered using a detailed reaction mechanism. The bimolecular rate constant over the pressure range considered herein was determined to be k1a = 7.2 × 1015 exp(−E/RT), with k1a in cm3/mol s and E = 45.1 ± 1.2 kcal/mol. This second-order rate coefficient describes the silane decomposition reaction over the entire range of temperatures and pressures herein a...