Investigation of spectroscopic and kinetic features of the radicals produced in gamma irradiated butylated hydroxyanisole

Abstract

In the present work, spectroscopic, room- and high-temperature kinetic features of the radicals produced upon gamma irradiation of butylated hydroxyanisole (BHA) were reported using electron spin resonance (ESR) spectroscopy. While unirradiated BHA samples exhibited no ESR signals, irradiated ones presented an unresolved ESR spectrum with three characteristic resonance peaks extending over a magnetic field region of about 3.5 mT. An evaluation technique based on the variations of the spectrum pattern and the heights of the resonance peaks with microwave power, applied dose, storage time and temperature were adopted throughout the work. The results of the annealing studies performed at different temperatures above 290 K were used to calculate high-temperature kinetic features of the radical species responsible for the observed experiment's ESR spectrum. A model based on the presence of two radical species having different kinetic and spectroscopic features was found to best describe the observed spectrum and derived experimental data. The dosimetric potential of BHA was also investigated, and it was concluded that BHA could be used to measure gamma radiation doses in the range of 1–10 kGy with an accuracy better than 6%, even long after the irradiation. Two tentative radical species were also proposed and their spectroscopic parameters were determined by spectrum simulation calculations.