Rice-Ramsperger-Kassel-Marcus theoretical prediction of high-pressure Arrhenius parameters by nonlinear regression: application to silane and disilane decomposition
暂无分享,去创建一个
Arrhenius parameters are estimated for silane and disilane thermal decomposition reactions by direct regression of RRKM predictions on published static and shock-tube data. For silane decomposition, they find E/sub infinity/ = 57.4-61.1 kcal/mol and log A/sub infinity/ = 14.9-16.3, while for disilane they find E/sub infinity/ = 51.1-52.5 kcal/mol and log A/sub infinity/ = 15.2-16.2. The lower limiting values correspond to inclusion of negative temperature dependence in the collision efficiency, while the higher values correspond to inclusion of weak or negligible temperature dependence. The Arrhenium parameters for both silane and disilane decomposition differ substantially from previously published values. For silane, they predict preexponentials approximately an order of magnitude greater than the previous values for the same activation energy. For disilane, they find A/sub infinity/ is roughly an order of magnitude higher than the literature values and E/sub infinity/ is greater by more than 2 kcal/mol. Falloff curves for both silane and disilane decomposition are given. Implications of these results for the activation energy of SiH/sub 2/ insertion into H/sub 2/ and SiH/sub 4/ and for ..delta..H/sub f//sup 0/(SiH/sub 2/) are discussed.