ESR signals in bones: interference from Fe3+ ions and a new method of dating

A study of the fading of the electron spin resonance (ESR) dating signal induced by laboratory γ irradiation in modern and ancient bone has shown that the rate of fading is related to the age of the bone. The observed initial rate of decay of the signal appears to be smaller the older the sample and the relative size of the final signal to be related to the age of the sample. This new method of dating is complementary to the usual ESR method but has some advantages. Other results show that the accumulation of Fe3+ ions in bone can affect the dating signal and therefore the apparent age of the bone. A method of overcoming this problem is discussed. (author)