title: EPR dating CO2- sites in tooth enamel apatites by ENDOR and triple resonance.
abstract: In this work we combine electron paramagnetic resonance (EPR), high-resolution electron nucleus double resonance (ENDOR) and general triple resonance (GTR) spectroscopies, to study the local environment of the CO2- groups created by ionizing radiation in fossil tooth enamel. We demonstrate that the CO2- groups occupy slightly modified phosphate sites in the hydroxyapatite lattice. In quaternary shark enamel we found these groups to be interacting with water molecules in the apatite channels. The absence of water molecules as first neighbors in mammalian samples indicate, however, that these molecules are not significantly responsible for the stabilization of CO2- dating centers in enamel.
authors.affiliation: Instituto de Física, Universidade Federal do Rio de Janeiro, Brazil.
authors.forename: N V
authors.initials: NV
authors.lastname: Vugman
authors.forename: A M
authors.initials: AM
authors.lastname: Rossi
authors.forename: S E
authors.initials: SE
authors.lastname: Rigby
mesh_terms: D000818:Animals; D002245:Carbon Dioxide / Q000032:analysis / Q000737:chemistry*; D003743:Dental Enamel / Q000737:chemistry*; D017886:Durapatite / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D018397:Equidae; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D015394:Molecular Structure; D010527:Perissodactyla; D012754:Sharks
chemical_list: D002245:Carbon Dioxide; D017886:Durapatite