2012ApJ...761..178K

We present a combined experimental and theoretical study on the formation processes and ionization energies of small organo-silicon molecules of the formula SiC₂H_x(x = 0, 1, 2). These organic molecules are considered important benchmark systems in understanding the formation of silicon- and carbon-bearing grains in the outflow of carbon stars. The studies identify four distinct (hydrogenated) silicon-carbon molecules together with their ionization energies: c-SiC₂[9.75±0.10 eV; 9.83±0.05 eV], l-HCCSi [7.00 ± 0.05 eV], c-SiC₂ H [7.27±0.05 eV], and c-SiC₂H₂[9.05±0.05 eV; 8.96 ± 0.05 eV] with numbers in italics depicting computed data. Implications of these results to the non-equilibrium chemistry in shocked regions of circumstellar envelopes of carbon stars are also discussed.