LABORATORY STUDIES ON THE INFRARED ABSORPTIONS OF HYDROGENATED CARBON-SILICON CLUSTERS: DIRECTING THE IDENTIFICATION OF ORGANOMETALLIC SiCHx SPECIES TOWARD IRC +10216

Silicon-bearing species of the molecular formula SiCHx (x 1⁄4 1 6) are plausible candidates for organometallic molecules that might be present in the circumstellar envelope of IRC +10216. Combining matrix-isolation laboratory experiments with computed vibrational spectra of these molecules, we have observed several fundamentals of the new silicon-containing radicals SiCH3 and SiCH5, in addition to the well-known SiCH4 and SiCH6 species, via infrared spectroscopy. These bands can now be used to search for hydrogen-deficient silicon-carbon–carrying molecules in the circumstellar envelope of the carbon star IRC +10216; the column densities of these species will yield valuable clues to the formation of silicon carbide molecules (SiC), together with their aggregates and partially hydrogenated clusters in the interstellar medium. Subject headinggs: astrochemistry — ISM: molecules — methods: laboratory — molecular processes