title: Massive isotopic effect in vacuum UV photodissociation of N2 and implications for meteorite data.
abstract: Nitrogen isotopic distributions in the solar system extend across an enormous range, from -400‰, in the solar wind and Jovian atmosphere, to about 5,000‰ in organic matter in carbonaceous chondrites. Distributions such as these require complex processing of nitrogen reservoirs and extraordinary isotope effects. While theoretical models invoke ion-neutral exchange reactions outside the protoplanetary disk and photochemical self-shielding on the disk surface to explain the variations, there are no experiments to substantiate these models. Experimental results of N2 photolysis at vacuum UV wavelengths in the presence of hydrogen are presented here, which show a wide range of enriched δ(15)N values from 648‰ to 13,412‰ in product NH3, depending upon photodissociation wavelength. The measured enrichment range in photodissociation of N2, plausibly explains the range of δ(15)N in extraterrestrial materials. This study suggests the importance of photochemical processing of the nitrogen reservoirs within the solar nebula.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0356; subrata@ucsd.edu.
authors.forename: Subrata
authors.initials: S
authors.lastname: Chakraborty
authors.affiliation: The Fritz Haber Research Center for Molecular Dynamics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel;
authors.forename: B H
authors.initials: BH
authors.lastname: Muskatel
authors.affiliation: Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0356;
authors.forename: Teresa L
authors.initials: TL
authors.lastname: Jackson
authors.affiliation: Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720; and.
authors.forename: Musahid
authors.initials: M
authors.lastname: Ahmed
authors.affiliation: The Fritz Haber Research Center for Molecular Dynamics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel; Department of Chemistry and Biochemistry, Crump Institute for Molecular Imaging, and Department of Molecular and Medical Pharmacology, University of California, Los Angeles, CA 90095.
authors.forename: R D
authors.initials: RD
authors.lastname: Levine
authors.affiliation: Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0356;
authors.forename: Mark H
authors.initials: MH
authors.lastname: Thiemens
keywords: nitrogen isotopes; organic molecules; perturbation