Spectrum decomposition of the angular measurements of fossil tooth enamel fragments using an automated simulated annealing (SA) procedure shows that the mix CO2− radicals generated by laboratory irradiation is significantly different to that of the natural sample. The naturally irradiated sample contains about 10% of non-oriented CO2− radicals and a mix of 35:65 orthorhombic to axial CO2− radicals. In contrast, laboratory irradiation generated about 40% of non-oriented radicals and a large amount of orthorhombic CO2− radicals, while we failed to detect any axial CO2− radicals. The results indicate that geological aging of the sample incurs various annealing and transfer processes; their precise nature is yet unknown. Nevertheless, the understanding of the formation and transfer processes that leads to the observed mix of CO2− radicals in fossil tooth enamel is essential for the reliable application of ESR dating.
Joannes-Boyau, R, Grun, R & Bodin, T 2010, 'Decomposition of the laboratory gamma irradiation component of angular ESR spectra of fossil tooth enamel fragments', Applied Radiation and Isotopes, vol. 68, no. 9, p..1798-1808.
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