IONIC REACTIONS IN GASEOUS MIXTURES OF MONOSILANE AND ETHYLENE

In ionized mixtures of monosilane and ethylene the only major ions that are observed to undergo collision reactions with the opposite molecule are C2H2+, C2H4+, and SiH2+. The principal reactions of both C2H2+ and C2H4+ are those involving H2- (or H and H- in one step) abstraction from SiH4. The principal reaction of SiH2+ with C2H4 is to form SiCH3+ and CH3. Rate constants for all the reactions of C2H2+ and C2H4+ with SiH4 and of SiH2+ with C2H4 are reported. Isotope labeling experiments indicate reactive intermediates in which complete mixing of hydrogen atoms takes place. The very fast reactions of C2H4+ with SiH4 and SiH2+ with C2H4 provide a rationale for the effects of C2H4 on the radiolysis of monosilane.