High-resolution oscillator strength measurements of the v′ = 0,1 bands of the B-X, C-X, and E-X systems in five isotopologues of carbon monoxide

G. Stark, A. N. Heays, James Lyons, P. L. Smith, M. Eidelsberg, S. R. Federman, J. L. Lemaire, L. Gavilan, N. De Oliveira, D. Joyeux, L. Nahon

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20 Scopus citations

Abstract

We report oscillator strengths for six strong vibrational bands between 105.0 and 115.2 nm, associated with transitions from the v = 0 level of the X 1Σ+ ground state to the v = 0 and 1 levels of the B 1Σ+, C 1Σ+, and E 1Π states, in 12C16O, 12C 17O, 12C18O, 13C16O, and 13C18O. These measurements extend the development of a comprehensive database of line positions, oscillator strengths, and linewidths of photodissociating transitions for all astrophysically relevant CO isotopologues. The E-X bands, in particular, play central roles in CO photodissociation and fractionation models of interstellar clouds and circumstellar disks including the early solar nebula. The resolving powers of the room-temperature measurements, R = 300,000-400,000, allow for the analysis of individual line strengths within bands; the measurements reveal J-dependences in the branch intensities of the C(v = 0,1)-X(0) and E(v = 0,1)-X(0) bands in all isotopologues. Minimal or no isotopologue dependence was found in the f-values of the C(v = 0,1)-X(0) and E(v = 0,1)-X(0) bands at a ∼5% uncertainty level. Revised dissociation branching ratios for the C(v = 0,1) and E(v = 0,1) levels are computed based on these f-values. The weak isotopologue dependence of the f-values presented here eliminates this mechanism as an explanation for the large 17O enrichments seen in recent laboratory photolysis experiments on CO at wavelengths from 105 to 108 nm.

Original languageEnglish (US)
Article number67
JournalAstrophysical Journal
Volume788
Issue number1
DOIs
StatePublished - Jun 10 2014

Keywords

  • ISM: molecules
  • methods: laboratory: molecular
  • molecular data
  • techniques: spectroscopic

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Stark, G., Heays, A. N., Lyons, J., Smith, P. L., Eidelsberg, M., Federman, S. R., Lemaire, J. L., Gavilan, L., De Oliveira, N., Joyeux, D., & Nahon, L. (2014). High-resolution oscillator strength measurements of the v′ = 0,1 bands of the B-X, C-X, and E-X systems in five isotopologues of carbon monoxide. Astrophysical Journal, 788(1), [67]. https://doi.org/10.1088/0004-637X/788/1/67