Radiation damage dating methods

Abstract

When dielectric solids are exposed to ionizing radiation, metastable electrons occur and can be detected by electron spin resonance (ESR). Measurements are possible by employing commercial ESR spectrometers which can sense the absorption of microwave radiation by the trapped electrons when they are subjected to a strong magnetic field, which promotes splitting of the energies of unpaired electrons. How this phenomenon takes place is dependent upon whether their magnetic moments are aligned parallel to or opposite the applied field. ESR dating is based on such measurements of unpaired electrons trapped in crystal defects. Such quasi-‘free’ electrons are produced through geological time by natural radiation arising from the decay of radioactive elements and also cosmic radiation.