High-Temperature Kinetics of Si + N2O

Article abstract of DOI:10.1021/j100071a022

In the present study the very fast high-temperature thermal decomposition of silane was used as a Si atom source to initiate its reactions with N2O.The experiments were performed behind reflected shock waves in SiH4/N2O/Ar systems by applying Atomic Resonance Absorption Spectroscopy (ARAS) for detecting Si and N atoms.Initial mixtures of 0.5 - 50 ppm SiH4 and 25 - 200 ppm N2O were used to perform experiments in the temperature range 1780 K /<- products (R3; k₃), was determined by fitting calulated to measured profiles.From energetical reasons reaction R3 can proceed via two exothermic product channels: Si + N2O ->/<- SiN + NO (R3a; k_3a) and Si + N2O ->/<- SiO + N2 (R3b; k_3b).To separate both possible channels, N atoms were measured, which are to be expected from secondary reactions including the products of the channel (R3a).Again by computer fittings rate coefficients for k_3a were obtained, which can be summarized by the following Arrhenius expression: k_3a = 5.0 x 10¹⁴ exp(-8100 K/T) cm³ mol^-1 s^-1 (+/- 50 percent).From the results of both, Si and N atom measuremetns, a mean value for the remaining rate coefficient k_3b = 8.0 x 10¹³ cm³ mol^-1 s^-1 (+/- 50 percent) was obtained.Detailed computer simulations based on a proposed reaction mechanism revealed estimates of further rate coefficients.