title: Kinetic isotopic fractionation and the origin of HDO and CH3D in the Solar System.
abstract: It is argued that photochemical processes, driven by ultraviolet starlight, could lead to large deuterium fractionation for H2O and CH4 relative to H2 in the primitive solar nebula.  Implications for deuterium enrichment observed in planetary atmospheres are briefly discussed.
authors.affiliation: Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena 91125, USA.
authors.forename: Y L
authors.initials: YL
authors.lastname: Yung
authors.forename: R R
authors.initials: RR
authors.lastname: Friedl
authors.forename: J P
authors.initials: JP
authors.lastname: Pinto
authors.forename: K D
authors.initials: KD
authors.lastname: Bayes
authors.lastname: Wen J-S
mesh_terms: D001272:Atmosphere; D003903:Deuterium; D005118:Extraterrestrial Environment; D006859:Hydrogen / Q000737:chemistry; D017665:Hydroxyl Radical / Q000737:chemistry; D007554:Isotopes; D008956:Models, Chemical; D010777:Photochemistry; D010782:Photolysis; D016083:Planets; D016082:Solar System; D014867:Water / Q000737:chemistry
chemical_list: D007554:Isotopes; D014867:Water; D017665:Hydroxyl Radical; D006859:Hydrogen; D003903:Deuterium