ESR study on the spatial distribution of radicals trapped in the heavy ion-irradiated <i>n</i>-eicosane single crystal

Abstract

Single crystals of n−eicosane were subjected to the irradiation of helium, carbon, and nitrogen ions accelerated with the cyclotron, and the results were compared with those obtained by 60Co γ-ray irradiation. Irradiation was carried out at 77 °K. The nature and the spatial distribution of free radicals produced in the crystals were investigated by an ESR technique. The principal radical is –CH2ĊHCH2– (I) and the minor one, CH3ĊHCH2– (II); the linewidth and decay of these radicals were found to be LET-dependent. The ESR results indicate that radicals are trapped in two regions closely and sparsely; the relative distribution in the two regions is dependent on the LET of radiations used. The mean separation between the radicals trapped in the close proximity was estimated to be approximately 16 Å.