Electron spin resonance (ESR) studies of CO2- radicals in irradiated A and B-type carbonate-containing apatites
ESR spectra of irradiated carbonate-containing hydroxyapatites are complex and strongly dependent on the method of preparation of these materials. This paper describes results of our studies of the ESR spectra of irradiated A- and B-type carbonated hydroxyapatites. The most intense and stable lines in these spectra are attributed to CO2- radicals. The ESR spectrum of A-type carbonated apatite can be predominantly due to either axial or orthorhombic CO2- species, depending on whether the apatite was cooled in or without a CO2 flow. The B-type carbonated apatite has an ESR spectrum composed basically of signals from isotropic and orthorhombic CO2- species. These signals are different in intensity, line width, and g-factor for samples heated for 3 h at 200, 400 and 600 degrees C. The effect of the method of preparation of the A- and B-type carbonated apatites on the ESR spectra and the application of these materials to the ESR dating and dosimetry are discussed.
Schramm
DU
Centro Brasileiro de Pesquisas Fisicas, Rio de Janeiro, Brazil.
Rossi
AM