Identification of higher order silanes during monosilane pyrolysis using gas chromatography-mass spectrometry

Abstract

a b s t r a c tThere is a deficit of ways to detect higher order silane isomers during silane pyrolysis. Thus, a novel instrument utilizing gas chromatography-mass spectrometry (GC-MS) for detection of higher order silanes has been developed. The instrument enables us to separate higher order silane species using gas chromatography before they are introduced to the mass spectrometer, thereby obtaining spectra of separate isomers, rather than overlaid spectra. In this contribution we describe the details of the GC-MS system. We compare our GC-separated mass spectra of mono-, di-and trisilane to mass spectra of these species available in the literature. Further, we present mass spectra of the tetrasilane isomers n-tetrasilane (n-Si 4 H 10 ), silyltrisilane (i-Si 4 H 10 ) and cyclotetrasilane (cyclo-Si 4 H 8 ) and of the pentasilane isomers n-pentasilane (n-Si 5 H 12 ), silyltetrasilane (i-Si 5 H 12 ) disilyltrisilane (neo-Si 5 H 12 ) and cyclopentasilane (cyclo-Si 5 H 10 ). Six of these mass spectra are previously unpublished. Based on the fragmentation pattern in the tetra-and pentasilane mass spectra, we are able to acquire mass spectra of silanes with up to eight silicon atoms. Finally, we apply the novel detection technique to a silane pyrolysis reactor to track the outlet concentration of higher order silanes as function of reactor temperature. We believe that the detection technique that we present here may open the door for validation of monosilane pyrolysis models, and thus constitute a roadmap for future research in this field.

Stable “snow lantern-like” aggregates of silicon nanoparticles suitable as a drug delivery platform

“…The complex thermal SiH 4 decomposition process includes formation of different higher order silane species (Si x H y ) that eventually grow into polymeric chains and rings, and the rings finally stack into complexes. 26,27 At this stage, the reactions are exothermic and irreversible. To grow stable aggregate particles, the reaction parameters were adjusted to maximize formation of a large number of nuclei, such that each particle would compete for the same precursor gas and thus be limited in size.…”

Infrared spectra of SinH4n−1+ ions (n = 2–8): inorganic H–(Si–H)n−1 hydride wires of penta-coordinated Si in 3c–2e and charge-inverted hydrogen bonds

“…1,26 Recently, higher-order silanes have been identified during monosilane pyrolysis by gas chromatography-mass spectrometry. 21 From an astrochemical point of view, Si and H are amongst the ten most abundant elements in the universe, and thus Si n H m molecules and their ions are expected to occur in the interstellar medium, although so far only SiH 4 has been identified. 22 In the laboratory, saturated Si n H 2n+2 polysilanes up to n = 19 have been produced from bombarding SiH 4 ices with electrons and detected by mass spectrometry.…”

“…Hydrogen passivation converts reactive Si n clusters into stable polysilanes nanostructures (Si n H m ), with potential applications of their derivatives and ions in material science, inorganic chemistry, catalysis, plasma- and astrochemistry, and theoretical chemistry. 1–25 For example, polysilane oligomers and their radical ions reveal interesting electronic, photophysical, and optical properties arising from substantial σ -delocalization of the bonding Si–Si electrons. 1,26 Recently, higher-order silanes have been identified during monosilane pyrolysis by gas chromatography–mass spectrometry.…”