Fourier transform infrared spectroscopic and density functional theoretical studies of silicon-carbon molecules

Abstract

Astronomers, experimentalists and theorists have produced a great deal of research on SinCm species, because of their potential applications to astrophysics and the study of Group IV molecules. The present work is part of this on-going research and we report here, the synthesis and observation of vibrational fundamentals of silicon-carbon species, SiC5 and SiC5Si. The infrared spectrum of SiC5 was observed by trapping the vapor from the Nd:YAG laser ablation of sintered Si/C rods in solid Ar at ~20 K. Measurements of ??C and ??,??Si isotopic shifts have enabled the identification of the v4(s) vibrational fundamental of the linear isomer of SiC5Si at 936.9 ? 0.2 cm??.The observed isotopic shifts are in excellent agreement with the predictions of DFT (density functional theory) calculations at the B3LYP/cc-pVDZ level. SiC5Si was produced using argon matrix trapping and Nd:YAG laser ablation of a sintered 30% Si/ 70%??C rod in solid Ar at ~20 K. The ??C and ??,??Si isotopic shifts were observed, and upon comparison with the calculations of DFT-B3LYP/cc-pVDZ, are in excellent agreement. This leads to a confident identification of the v5(s?) fundamental of linear SiC5Si at 1590.8 ? 0.2 cm??. A second fundamental, v4(s?), can only be tentatively identified at 2021.0 cm?? because near-lying absorptions belonging to other species overlap its isotopic shift pattern.