Communication: The ground electronic state of Si{sub 2}C: Rovibrational level structure, quantum monodromy, and astrophysical implications
- Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, Massachusetts 02138 (United States)
- JILA, National Institute of Standards and Technology and Department of Physics, University of Colorado, Boulder, Colorado 80309 (United States)
- Department of Chemistry, University of Colorado, Boulder, Colorado 80309 (United States)
- Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712 (United States)
We report the gas-phase optical detection of Si{sub 2}C near 390 nm and the first experimental investigation of the rovibrational structure of its {sup 1}A{sub 1} ground electronic state using mass-resolved and fluorescence spectroscopy and variational calculations performed on a high-level ab initio potential. From this joint study, it is possible to assign all observed K{sub a} = 1 vibrational levels up to 3800 cm{sup −1} with confidence, as well as a number of levels in the K{sub a} = 0, 2, and 3 manifolds. Dixon-dip plots for the bending coordinate (ν{sub 2}) allow an experimental determination of a barrier to linearity of 783(48) cm{sup −1} (2σ), in good agreement with theory (802(9) cm{sup −1}). The calculated (K{sub a}, ν{sub 2}) eigenvalue lattice shows an archetypal example of quantum monodromy (absence of a globally valid set of quantum numbers) that is reflected by the experimentally observed rovibrational levels. The present study provides a solid foundation for infrared and optical surveys of Si{sub 2}C in astronomical objects, particularly in the photosphere of N- and J-type carbon stars where the isovalent SiC{sub 2} molecule is known to be abundant.
- OSTI ID:
- 22490810
- Journal Information:
- Journal of Chemical Physics, Vol. 142, Issue 23; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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