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
- Department of Physics, Wellesley College, Wellesley, MA 02481 (United States)
- Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden (Netherlands)
- School of Earth and Space Exploration, Arizona State University, 781 South Terrace Road, Tempe, AZ 85281 (United States)
- 93 Pleasant Street, Watertown, MA 02472 (United States)
- Observatoire de Paris, 5 place Jules Janssen, F-92195 Meudon (France)
- Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606 (United States)
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 {sup 1}Σ{sup +} ground state to the v = 0 and 1 levels of the B {sup 1}Σ{sup +}, C {sup 1}Σ{sup +}, and E {sup 1}Π states, in {sup 12}C{sup 16}O, {sup 12}C{sup 17}O, {sup 12}C{sup 18}O, {sup 13}C{sup 16}O, and {sup 13}C{sup 18}O. 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 {sup 17}O enrichments seen in recent laboratory photolysis experiments on CO at wavelengths from 105 to 108 nm.
- OSTI ID:
- 22356655
- Journal Information:
- Astrophysical Journal, Vol. 788, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ASTROPHYSICS
BRANCHING RATIO
CALCIUM ISOTOPES
CARBON MONOXIDE
DISSOCIATION
GROUND STATES
LINE WIDTHS
OSCILLATOR STRENGTHS
OXYGEN ISOTOPES
PHOTOLYSIS
RESOLUTION
SOLAR NEBULA
TEMPERATURE RANGE 0273-0400 K
VIBRATIONAL STATES
WAVELENGTHS