Electron spin resonance dating
Electron spin resonance dating, or ESR dating, is a technique used to date materials, for which radiocarbon dating does not work well, such as minerals (e.g. carbonates, silicates, sulphates), inorganic biological materials (e.g., tooth enamel), inorganic archaeological materials (e.g., ceramics) and certain foods. Electron spin resonance dating was first introduced to the science community in 1975, when Japanese nuclear physicist Motoji Ikeya dated a speleothem in Akiyoshi Cave, Japan. ESR dating measures the amount of unpaired electrons in crystalline structures that were previously exposed to natural radiation. The age of a substance can be determined by measuring the dosage of radiation since the time of its formation.