The thermal history of maize kernels determined by electron spin resonance

Electron spin resonance (ESR) can be sued to determine the thermal history of charred organic material. Maize seeds were heated under controlled condi tions in order to produce calibration curves relating g-values (the rate of electron splitting) and spin intensities (the number of spin centres) to h eating temperatures, times and conditions. These experiments reproduced res ults that had been previously obtained by other laboratories, with some min or exceptions. The calibration curves were then used to reconstruct the the rmal histories of charred maize kernels from several prehistoric sites in e astern North America. At these sties, the differing thermal histories of ma ize kernels are correlated with depositional contexts.