A QUANTUM BAND MODEL OF THE {nu}{sub 3} FUNDAMENTAL OF METHANOL (CH{sub 3}OH) AND ITS APPLICATION TO FLUORESCENCE SPECTRA OF COMETS
Journal Article
·
· Astrophysical Journal
- Solar System Exploration Division, Mailstop 690.3, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
Methanol (CH{sub 3}OH) radiates efficiently at infrared wavelengths, dominating the C-H stretching region in comets, yet inadequate quantum-mechanical models have imposed limits on the practical use of its emission spectra. Accordingly, we constructed a new line-by-line model for the {nu}{sub 3} fundamental band of methanol at 2844 cm{sup -1} (3.52 {mu}m) and applied it to interpret cometary fluorescence spectra. The new model permits accurate synthesis of line-by-line spectra for a wide range of rotational temperatures, ranging from 10 K to more than 400 K. We validated the model by comparing simulations of CH{sub 3}OH fluorescent emission with measured spectra of three comets (C/2001 A2 LINEAR, C/2004 Q2 Machholz and 8P/Tuttle) acquired with high-resolution infrared spectrometers at high-altitude sites. The new model accurately describes the complex emission spectrum of the {nu}{sub 3} band, providing distinct rotational temperatures and production rates at greatly improved confidence levels compared with results derived from earlier fluorescence models. The new model reconciles production rates measured at infrared and radio wavelengths in C/2001 A2 (LINEAR). Methanol can now be quantified with unprecedented precision and accuracy in astrophysical sources through high-dispersion spectroscopy at infrared wavelengths.
- OSTI ID:
- 22016312
- Journal Information:
- Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 747; ISSN ASJOAB; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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