title: X- and Q-band electron paramagnetic resonance of CO2- in hydroxyapatite single crystals.
abstract: Both X- and Q-band electron paramagnetic resonance (EPR) research has been conducted using slightly carbonated hydroxyapatite (HAp) single crystals after exposure to ionizing radiation. Below a temperature of 90 K, O(-) and CO(2-) radicals were detected, whereas at room temperature only CO(2-) spectra could be observed. The O(-) ion has previously been investigated in high-purity HAp single crystals, whereas EPR spectra of CO(2-) in HAp single crystals have not been reported. Both paramagnetic defects exhibit EPR angular variations in planes containing the c axis of the crystal from which spin Hamiltonian parameters were derived. Arguments are given for the presence of two CO(2-) defects in the irradiated HAp single crystals.
authors.affiliation: Laboratory for Crystallography and Study of the Solid State, Ghent University, Krijgslaan 281-S1, B-9000 Gent, Belgium.
authors.forename: G C
authors.initials: GC
authors.lastname: Vanhaelewyn
authors.forename: R A
authors.initials: RA
authors.lastname: Morent
authors.forename: F J
authors.initials: FJ
authors.lastname: Callens
authors.forename: P F
authors.initials: PF
authors.lastname: Mathys
mesh_terms: D002254:Carbonates / Q000032:analysis*; D003460:Crystallization; D017886:Durapatite / Q000737:chemistry / Q000528:radiation effects*; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D008872:Microwaves; D008956:Models, Chemical; D013696:Temperature
chemical_list: D002254:Carbonates; D017886:Durapatite