Electron spin resonance dating
Electron Spin Resonance Dating, or ESR dating, is a technique used to date newly formed materials, which Radiocarbon dating cannot, like carbonates, tooth enamel, or materials that have been previously heated like igneous rock. Electron spin resonance dating was first introduced to the science community in 1975, when 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. Age of substance can be determined by measuring the dosage of radiation since the time of its formation.
Electron Spin Resonance Dating is being used in fields like radiation chemistry, biochemistry, and as well as geology, archaeology, and anthropology. ESR dating is used instead of Radiocarbon dating because ESR dating can date newly formed materials or previously heated rock. The dating of buried teeth has served as the basis for the dating of human remains. Studies have been used to date burnt flint and quartz found in certain ancient ceramics. Newer ESR dating applications include dating previous earthquakes from fault gouge, past volcanic eruptions, and tectonic activity along coastlines.
Electron spin resonance dating can be described as trapped charge dating. Radioactivity causes negatively charged electrons to move from a ground state, the valence band, to a higher energy level at the conduction band. After a short time, electrons eventually recombine with the positively charged holes left in the valence band. Since natural materials are not always perfect, sometimes electrons are trapped between energy levels. The trapped electrons form para-magnetic centers and give rise to certain signals that can be detected under an ESR spectrometry. The amount of trapped electrons corresponds to the magnitude of the ESR signal. This ESR signal is directly proportional to the number of trapped electrons in the mineral, the dosage of radioactivity substances, and the age.
The electron spin resonance age of a substance is found from the following equation:
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