The reactions of primary ions Si+, SiH+, SiH2+, and SiH3+ with SiH4 are observed and reported, along with relative and absolute rate constants for the reactions observed. SiH2+ and SiH3+ are seen to undergo H− transfer reactions with large rate constants. All of the ions also participate in reactions yielding higher molecular weight ions containing two silicon atoms. The rate constants for many of these reactions are also large and suggest that the production of higher silanes from silane in activated systems (discharges, nuclear recoil experiments, etc.) may be due in part to the production of these ions.

The reactions of monosilane (SiH4) and disilane (SizHs) with Clz, Fz, and CIF have been studied. The monosilanetuorine a_nd disilane-fluorine systems are characterized by strong emission from the A(zZ+)-X(rII) transition of SiF, the A ( 2 A~) -X ( 2 A l ) transition of SiF3, and the A(2A)-X(211) transition of SiH. Some evidence indicates the possible observation of the a(4A)-X(211) transition in SiH. By contrast, the principal emission spectrum in the monosilane-chlorine and disilanechlorine reactions is the IA"-'A' transition of HSiCI. A continuum emission feature may belong to Sic12 or SiC13. These results indicate specific reaction mechanisms which include both atomic and molecular halogen reacting with intermediate silylene (SiH2) radicals and silicon atoms.Many organic and inorganic hydrides react with halogens to give vibrationally excited hydrogen halides as products. Consequently, these systems have received attention as potential sources for infrared chemical lasers.2 However, inorganic oxidation reactions are often highly exothermic and, as a result, produce a rich variety of electronically excited intermediates.' This suggests the study of gas-on-gas reactions, as an alternative to the presently favored metal-gas reaction^,^ as candidates for a visible chemical laser.The complex nature of flame reactions enhances the possibility of observing new spectroscopic transitions.s In some cases, by identifying reaction intermediates from previously reported spectra, individual kinetic steps may be inferred. Alternatively, these reactions could be used to give a high flux of radicals, which are otherwise difficult to prepare in sufficient concentration, for subsequent kinetic and/or spectroscopic studies.We report here the chemiluminescent spectra of the reactions of monosilane (SiH4) and disilane (Si2H6) with F2, CI2, and CI F. The monosilane-fluorine and disilane-fluorine reactions are characterized by an inner purple flame (emission by SiH* at 4150 A) surrounded by a blue region (emission from SiF* at -4375-4550 A). The disiiane-chlorine and monosilane-chlorine flame is green, as a result of emission from HSiCI*. In an earlier study of the monosilane-chlorine reaction, a green emission was observed and attributed to SiCI*.2b Our study definitely shows that the chemiluminescence is from HSiCI* and not from SiCI*.The requirement that a single step be sufficiently exothermic to account for the observed chemiluminescence suggests the following reactions,

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Endothermic ion-molecule reactions in silane are reported together with rate constants for the observed reactions. Si2+ is observed only from endothermic reactions of Si+ and SiH2+ with silane. Endothermic as well as exothermic channels are observed for the formation of Si2H+, Si2H2+, and Si2H3+. The kinetic energy dependence of reactions yielding Si2H+, Si2H2+, Si2H3+, and Si2H4+ products is reported and analyzed in terms of the mechanism and kinematics of fragmentation for the excited intermediate ion.