ESR identification of radiation damage in synthetic apatites: a study of the 13C-hyperfine coupling.

Although radiogenic free radicals are widely used as molecular probes in biological calcified tissues, their nature and their location remain controversial. In the present study we have synthesized and irradiated apatites in which 13CO3(2-) ions substitute hydroxyl or phosphate ions in hydroxyapatite. The 13C-couplings show that the carbon-centered radicals are CO2- --rather than CO3(3-)--the locations of which depend on the type of carbonate and the treatment of the sample.