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Astron. Astrophys. 364, 780-784 (2000)
Gas-phase formation of doubly-deuterated species
H. Roberts and
T.J. Millar
Department of Physics, UMIST, P.O. Box 88, Manchester M60 1QD, UK
Received 12 July 2000 / Accepted 19 October 2000
Abstract
We present the first results from a time-dependent chemical model to include a gas-phase reaction scheme for producing doubly-deuterated species. Under normal conditions the formation of these species is inefficient. However, when the effects of the freeze out of gas phase species onto grains is included in the chemistry we find that the fractionation of both singly and doubly deuterated species is enhanced.
We compare the predictions from our models with recent observations of deuterated molecules in L134N and find that, contrary to previous expectations, we can reproduce the observed levels of fractionation without recourse to an active grain-surface chemistry.
Key words: ISM:
abundances 
ISM: molecules
ISM: clouds
ISM: individual objects: LI34N
Send offprint requests to: H. Roberts (hhr@janus4.phy.umist.ac.uk)
Contents
- 1. Introduction
- 2. The models
- 3. Results
- 3.1. The gas-phase model
- 3.2. The accretion model
- 4. Comparison with observations
- 5. Discussion
- Acknowledgements
- References
© European Southern Observatory (ESO) 2000
Online publication: January 29, 2001
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