Abstract
This paper reviews the chemical processes responsible for fractionating deuterium in interstellar molecules. I show that this process is intrinsically a low temperature phenomenon and discuss how the degree of enhancement of the deuterium content of molecules is related to the physical conditions, particularly abundances, in molecular clouds. If significant amounts of abundant species, such as CO, are frozen out on to interstellar dust grains, the resulting enhancement in H2D+ can result in its abundance being greater than that of H3 + at 10 K. Transfer of the deuteron from H2D+ can then lead to the efficient formation of multiply deuterated species, such as NHD2 and ND3. Fractionation can also occur in grain surface reactions and some simple models are discussed.
Keywords
This is a preview of subscription content, log in via an institution.
Buying options
Tax calculation will be finalised at checkout
Purchases are for personal use only
Learn about institutional subscriptionsPreview
Unable to display preview. Download preview PDF.
References
Aikawa, Y., and Herbst, E.: 2001, ‘Two-Dimensional Distributions and Column Densities of Gaseous Molecules in Protoplanetary Disks. II. Deuterated Species and UV Shielding by Ambient Clouds’, Astron. Astrophys. 371, 1107–1117.
Blake, G.A., Qi, C., Hogerheijde, M.R., Gurwell, M.A., and Muhleman, D.O.: 1999, ‘Sublimation from Icy Jets as a Probe of the Interstellar Volitile Content of Comets’, Nature 398, 213–216.
Brown, P.D., and Millar, T.J.: 1989, ‘Grain Surface Formation of Multi-Deuterated Molecules’, Month. Not. Roy. Astron. Soc. 240, 25P–29P.
Brown, P.D., Charnley, S.B., and Millar, T.J.: 1988, ‘A Model of the Chemistry in Hot Molecular Cores’, Month. Not. Roy. Astron. Soc. 231, 409–417.
Caselli, P., Hasegawa, T.I., and Herbst, E.: 1998, ‘A Proposed Modification of the Rate Equations for Reactions on Grain Surfaces’, Astrophys. J. 495, 309–316.
Caselli, P., Walmsley, C.M., Tafalla, M., Dore, L., and Myers, P. C.: 1999, ‘CO Depletion in the Starless Cloud Core L1544’, Astrophys. J. 523, L165–L169.
Caselli, P., Stantcheva, T., Shalabiea, O., Shematovich, V.I., and Herbst, E.: 2002, ‘Deuterium Fractionation on Interstellar Grains Studied with Modified Rate Equations and a Monte Carlo Approach’, Plan. Space Sci. in press.
Ceccarelli, C., Castets, A., Loinard, L., Caux, E., and Tielens, A.G.G.M.: 1998, ‘Detection of Doubly Deuterated Formaldehyde Towards the Low-luminosity Protostar IRAS 16293–2422’, Astron. Astrophys. 338, 16293–2422.
Charnley, S.B., Tielens, A.G.G.M., and Rodgers, S.D.: 1997, ‘Deuterated Methanol in the Orion Compact Ridge’, Astrophys. J 482, L203–L206.
Cohen, S.D., and Hindmarsh, A.C.: 1996, ‘CVODE, a Stiff/Nonstiff ODE Solver in C’, Computers in Physics 10, 138–143.
Delsemme, A.H.: 2000, ‘1999 Kuiper Prize Lecture: Cometary Origin of the Biosphere’, Icarus 146, 313–325.
Gensheimer, P.D., Mauersberger, R., and Wilson, T.L.: 1996, ‘Water in Galactic Hot Cores’, Astron. Astrophys. 314, 281–294.
Gibb, A.G., and Little, L.T.: 1998, ‘Probing the Structure of Molecular Cloud Cores: Observations and Modeling of CI and C18O’, Month. Not. Roy. Astron. Soc. 295, 299–311.
Hatchell, J., Millar, T.J., and Rodgers, S.D.: 1998, ‘The DCN/HCN Abundance Ratio in Hot Molecular Cores’, Astron. Astrophys. 332, 695–702.
Jensen, M.J., Bilodeau, R.C., Safvan, C.P., Seiersen, K., Andersen, L.H., Pedersen, H.B., and Heber, O.: 2000, ‘Dissociative Recombination of H3O+HD2O+and D3O+’, Astrophys. J. 543, 764–774.
Larsson, M., Lepp, S.et al.: 1996, ‘Dissociative Recombination of H2D+ and the Cosmic Abundance of Deuterium’, Astron. Astrophys. 309, Ll-L3.
Leung, C.M., Herbst, E., and Huebner, W.F.: 1984, ‘Synthesis of Complex Molecules in Dense Interstellar Clouds via Gas-phase Chemistry - A Pseudo Time-Dependent Calculation’, Astrophys. J. Suppl. 56, 231–256.
Lis, D.C., Roueff, E., Gerin, M., Phillips, T.G., Coudert, L.H., van der Tak, F.F.S., and Schilke, P.:2002, ‘Detection of Triply Deuterated Ammonia in the Barnard 1 Cloud’, Astrophys. J. 571, L55–L58.
Loinard, L., Castets, A., Ceccarelli, C., Tielens, A.G.G.M., Fauré, A., Caux, E., and Duvert, G.: 2000, ‘The Enormous Abundance of D2CO in IRAS 16293–2422’, Astron. Astrophys. 359, 16293–2422.
Millar, T.J., and Freeman, A.: 1984, ‘Chemical Modelling of Molecular Sources1.TMC-l’, Month. Not. Roy. Astron. Soc. 207, 405–423.
Mousis, O., Gautier, D., and Coustenis, A.: 2002, ‘The D/H Ratio in Methane in Titan: Origin and History’, Icarus 159, 156–165.
Roberts, H., and Millar, T.J.: 2000a, ‘Modelling of Deuterium Chemistry and its Application to Molecular Clouds’, Astron. Astrophys. 361, 388–398.
Roberts, H., and Millar, T.J.: 2000b, ‘Gas-Phase Formation of Doubly-Deuterated Species’, Astron. Astrophys. 364, 780–784.
Roberts, H., Herbst, E., and Millar, T.J.: 2002, ‘The Importance of New Rate Coefficients for D Fractionation Reactions on Interstellar Chemistry’, Month. Not. Roy. Astron. Soc. 336, 283–290.
Roberts, H., and Millar, T.J.: 2002, in preparation.
Rodgers, S.D., and Charnley, S.C.: 2001, ‘Gas-phase Production of NHD2 in L134N’, Astrophys. J. 553, 613–617.
Rodgers, S.D., and Charnley, S.C.: 2002, ‘A Model of the Chemistry in Cometary Comae: Deuterated Molecules’, Month. Not. Roy. Astron. Soc. 330, 660–674.
Roueff, E., Tiné, S., Coudert, L. H., Pineau des Fôrets, G., Falgarone, E., and Gerin, M.: 2000, ‘Detection of Doubly Deuterated Ammonia in L134N’, Astron. Astrophys. 354, L63–L66.
Stantcheva, T., Caselli, P., and Herbst, E.: 2001, ‘Modified Rate Equations Revisited. A Corrected Treatment for Diffusive Reactions on Grain Surfaces’, Astron. Astrophys. 375, 673–679.
Stark, R., van der Tak, F.F.S., and van Dishoeck, E.F.: 1999, ‘Detection of Interstellar H2D+Emission’, Astrophys. J 521, L67–L70.
van der Tak, F.F.S., Schilke, P., Müller, H.S.P., Lis, D.C., Phillips, T.G., Gerin, M., and Roueff, E.: 2002, ‘Triply Deuterated Ammonia in NGC 1333’, Astron. Astrophys. 388, L53–L56.
Tiné, S., Roueff, E., Falgarone, E., Gerin, M., and Pineau des Fôrets, G.: 2000, ‘Deuterium Fractionation in Dense Ammonia Cores’, Astron. Astrophys. 356, 1039–1049.
Watson, W.D.: 1974, ‘Ion-Molecule Reactions, Molecule Formation, and Hydrogen-Isotope Exchange in Dense Interstellar Clouds’, Astrophys. J. 188, 35–42.
Williams, J.P., Bergin, E.A., Caselli, P., Myers, P.C., and Plume, R.: 1998, ‘The Ionization Fraction in Dense Cloud Cores’, Astrophys. J. 503, 689–699.
Author information
Authors and Affiliations
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2003 Springer Science+Business Media New York
About this chapter
Cite this chapter
Millar, T.J. (2003). Deuterium Fractionation in Interstellar Clouds. In: Kallenbach, R., Encrenaz, T., Geiss, J., Mauersberger, K., Owen, T.C., Robert, F. (eds) Solar System History from Isotopic Signatures of Volatile Elements. Space Sciences Series of ISSI, vol 16. Springer, Dordrecht. https://doi.org/10.1007/978-94-010-0145-8_6
Download citation
DOI: https://doi.org/10.1007/978-94-010-0145-8_6
Publisher Name: Springer, Dordrecht
Print ISBN: 978-94-010-3970-3
Online ISBN: 978-94-010-0145-8
eBook Packages: Springer Book Archive