Infrared spectroscopic detection of the methylsilyl (CH3SiH2, X2A′) and the silylmethyl (CH2SiH3, X2A′) radicals and their partially deuterated counterparts in low temperature matrices

Both the methylsilyl, CH3SiH2(X2A′), and the silylmethyl, SiH3CH2(X2A′), together with their partially deuterated isotopomers were identified for the first time via infrared spectroscopy in low temperature silane-methane matrices at 10 K upon exposure of the matrices with mono energetic electrons. Three fundamentals at 654 cm−1 (ν8), 1414 cm−1 (ν12), and 1251 cm−1 (ν5) (methylsilyl) and one absorption at 645 cm−1 (ν8) (silylmethyl) were detected; these assignments were confirmed by identifying also partially deuterated radicals through their absorptions at 781 cm−1 (ν7), 1415 cm−1 (ν12), 1419 cm−1 (ν4), and 1546 cm−1 (ν11) (d2-methylsilyl, CH3SiD2) and 582 cm−1 (ν8), 749 cm−1 (ν5), and 771 cm−1 (ν13) (d3-silylmethyl, SiD3CH2) in d4-silane-methane matrices. Since both silane and methane have been observed in the circumstellar envelope of the carbon star IRC+10216, our investigations assist in future infrared spectroscopic, astronomical searches for these species in interstellar space. Likewise, the knowledge of the infrared absorption features might help to follow the chemical evolution of organo-silicon CVD process via time resolved infrared spectroscopy.