DECAY KINETICS FOR ISOTROPIC RADICALS IN CARBONATES

Electron spin resonance (ESR) signals of isotropic CO3- and CO2- radic als are frequently encountered in irradiated carbonates. These centers are thought to be surrounded by water molecules. Until now, their the rmal annealing curves were generally described in terms of several sim ultaneous first order-reaction kinetics. A reinvestigation of some rec ent data allows us to conclude that, at sufficiently low temperatures, a second-order equal concentration dispersive kinetics suffices to re produce satisfactorily the decays. When the annealing temperature appr oaches that of the water departure, this mechanism becomes inadequate. Mixed first-and second-order classical reaction and 1.5-order reactio n kinetics have then been tentatively used.