Heavy-ion-induced free radical formation in solid DNA-constituents: quantitative and structural aspects

Abstract

Electron spin resonance (ESR) spectroscopy was used to study free radical formation in solid, polycrystalline pellets of DNA-constituents. Dose-yield curves were obtained at low (ca 90 K) and ambient temperatures, and were analyzed for initial G-values (radicals per 100 eV absorbed energy). At both temperatures, values of one or more orders of magnitude below the corresponding x-ray values were found. Combination of x-ray and heavy-ion irradiation indicated an enhanced radical destruction as probable cause of reduced G-values. Structural aspects as analyzed from the ESR-powder spectra revealed differences in initial, low-temperature radical population and in decay reactions upon annealing between heavy-ion bombardment and low-LET irradiation.