FTIR OBSERVATION VIBRATIONAL FUNDAMENTALS OF SiCH AND $H_{2}SiC_{2}H$ IN SOLID Ar

Abstract

Fourier transform infrared studies have resulted in the first observation of vibrational spectra of the linear SiCH and nonplanar $H_{2}SiCCH$ radicals produced by trapping the products of the vacuum ultraviolet photolysis of a mixture of $SiH_{4}$ silane, and $C_{2}H_{2}$ acetylene, in an Ar matrix at about 10 K. The silicon-carbon stretching mode $\nu_{1}(\sigma)$ of SiCH has been observed at $1010.4 cm^{-1}$. Two vibrational fundamentals of $H_{2}SiC_{2}H$ have been identified, the $v_{3}(a^{\prime})$, silicon-carbon stretching mode at $2055.6 cm^{-1}$ and the $v_{4}(a^{\prime})$, hydrogen-silicon bending mode at $926.8 cm^{-1}$. The results of extensive measurements of D and $^{13}C$ isotopic shifts are in good agreement with the predictions of coupled cluster ab initio calculations performed at the CCSD(T)/6-$31G^{\ast \ast}$ level and confirm the proposed identifications.