| Title | Deuterium enrichment of polycyclic aromatic hydrocarbons by photochemically induced exchange with deuterium-rich cosmic ices. | | Author(s) | Sandford SA, Bernstein MP, Allamandola LJ, Gillette JS, Zare RN | | Institution | NASA-Ames Research Center, Moffett Field, CA 94035-1000, USA. | | Source | Astrophys J 2000 Aug 1; 538(2 Pt 1):691-7. | | MeSH | Deuterium
Exobiology
Extraterrestrial Environment
Hydrogen
Ice
Meteoroids
Photochemistry
Photolysis
Polycyclic Compounds
Polycyclic Hydrocarbons, Aromatic
Research Support, U.S. Gov't, Non-P.H.S.
Ultraviolet Rays
| | Abstract | The polycyclic aromatic hydrocarbon (PAH) coronene (C24H12) frozen in D2O ice in a ratio of less than 1 part in 500 rapidly exchanges its hydrogen atoms with the deuterium in the ice at interstellar temperatures and pressures when exposed to ultraviolet radiation. Exchange occurs via three different chemical processes: D atom addition, D atom exchange at oxidized edge sites, and D atom exchange at aromatic edge sites. Observed exchange rates for coronene (C24H12)-D2O and d12-coronene (C24D12)-H2O isotopic substitution experiments show that PAHs in interstellar ices could easily attain the D/H levels observed in meteorites. These results may have important consequences for the abundance of deuterium observed in aromatic materials in the interstellar medium and in meteorites. These exchange mechanisms produce deuteration in characteristic molecular locations on the PAHs that may distinguish them from previously postulated processes for D enrichment of PAHs. | | Language | eng | | Pub Type(s) | Journal Article
| | PubMed ID | 11543580 |
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