Infrared spectroscopic identification of the methylsilylidyne (SiCH3, X 2A″) and the silenyl (H2CSiH, X 2A′) radicals in methane-silane matrices

The methylsilylidyne (SiCH3, X 2A″) and the silenyl (H2CSiH, X 2A′) radicals were identified via infrared spectroscopy in low temperature silane-methane matrices upon irradiation of the samples matrices with energetic electrons at 10 K. The ν4 and ν3 fundamentals of the methylsilylidyne species were detected at 1226 and 1371 cm−1, whereas one band of the silenyl radical showed up at 822 cm−1(ν6). These assignments were verified in partially deuterated matrices. Our studies suggest that these radicals are generated through radiolysis of silene (H2CSiH2, X 1A1) and its methylsilylene isomer (CH3SiH, X 1A′). The new absorptions of two SiCH3 isomers can be utilized in future spectroscopic studies of chemical vapor deposition processes and in astronomical searches of silicon-bearing organometallic molecules to better understand the chemistry of the circumstellar envelope of the carbon star IRC + 10216.