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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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We have fabricated a spectral imager for astronomy and aeronomy using collinear or noncollinear acousto-optic tunable filters (AOTFs). The AOTF provides high transparency, rapid tunability over a wide wavelength range, a capability of varying the bandwidth by more than an order of magnitude, high etendué, and linearly polarized output. We demonstrate here some typical observational applications of acousto-optic tunable filters used in several configurations at astronomical telescopes.