Investigations of the Reaction of Trimethylsilane with O(3P) Atoms

Abstract

The reaction O(,PJ) + (CH&SiH -products (1) has been investigated by the discharge/fast-flow method with mass spectrometric detection (DF-MS) over 298-773 K and by the flash photolysis/resonance fluorescence (FP-RF) technique over 293-549 K. The rate constants from both methods are in close accord and may be summarized by kl(T) = 5.6 X lo-" exp(-1005 K/7') cm3 molecule-' s-l for 290-770 K. There is reasonable agreement with previous room-temperature studies. kl is larger than k2 for 0 + SiH4 (2), similar to results for triethylsilane and triisopropylsilane [Buchta, Chr.; Stucken, D.-V.; Vollmer, J.-T.; Wagner, H. Gg. Z. Phys.Chem. Neue Folge, to be published], and tri-alkylation is seen to increase the reactivity of the Si-H bonds by similar amounts largely independent of the nature of the alkyl group. This silane activation occurs through lowering the energy barrier to abstraction to form O H + (CH3)3Si*. Ab initio analysis of this pathway at the MP2/6-31G*//HF/3-21G(*) level of theory gives relative energies for the transition states of reactions 1 and 2 that agree well with experiment.

Kinetic studies of the reactions of hydroxyl radicals with the methyl-substituted silanes SiHn(CH3)4−n (n=0 to 4) at room temperature

“…A similar paradox and a possible interpretation in frontier orbital terms was presented earlier for the reactions of silanes with O( 3 P) atoms [16]. In that case it was argued that as the degree of methylation increases, electron withdrawal by the methyl groups makes the Si atom more positive.…”

Determination of the Rate Constants for Bimolecular Reactions of O(3P) Atom with SiH4and SiHCl3

“…The oxygen atoms are consumed by the reaction with silanes, as well as the wall of reaction tube by the collision, as given in equations (5) and (6) (6) where, k bi is the rate constant of bimolecular reaction; k w is the first order rate constant for wall effect regarding the consumption due to O 2 and also reaction products. Near the injection point, the rate equation for the consumption of oxygen atom is described by the equation (I) since the reaction (5) where, represents the concentration of remaining O( 3 P) when the samples are completely consumed.…”

“…Buchta et al reported the experimental work on the reaction of O( 3 P) with silanes by discharge flow method and mass spectrometry. 5,6 The rate constant for the reaction of O( /RT] in the range of 298-773 K, however, the rate expression considered only hydrogen abstraction channel rather than total reaction pathways. 5 In this note, we report kinetic data on the measurements of total reaction pathways for reaction of O( …”

Mechanism and Interpolated Variational Transition State Rate Constant for the Reaction of Atomic H with Monoethylsilane

“…The gasphase reactions of alkylsilanes with various atoms and free radicals have been the active subject of many studies for a long time. [1][2][3][4][5][6][7][8][9][10][11][12][13] In this paper we present a theoretical study on the reaction of atomic H with monoethylsilane EtSiH 3 . The reasons for initiating such a work are 3-fold.…”

“…Alkylsilanes are common precursors used in chemical vapor deposition (CVD) to produce semiconductor devices. The gas-phase reactions of alkylsilanes with various atoms and free radicals have been the active subject of many studies for a long time. − In this paper we present a theoretical study on the reaction of atomic H with monoethylsilane EtSiH 3 . The reasons for initiating such a work are 3-fold.…”