An electron spin resonance study of radical decay in γ-ray irradiated pepper by thermal treatments

Abstract

We examined by electron spin resonance (ESR) spectroscopy the thermal decay of radicals as induced by γ-irradiation on pepper. Upon irradiation, the satellite signals were newly induced and appeared at the symmetric positions of the organic free radical, i.e., theg=2.0 signal. Heat treatment decreased the satellite signals exponentially. The ESR signal of the pepper heated for more than 10 min was essentially the same as that before irradiation. To evaluate the radical decay by heat treatment, we formulated a time-dependent master equation. We could evaluate the time constant of the radical decay on the basis of the general solution of the equation together with the non-linear least-squares method.