Effect of specific energy of heavy ions for 1,2,4,5-tetracyanobenzene radical anion formation

The absorption spectrum of poly(vinyl alcohol) (PVA) film doped with 1,2,4,5-tetracyanobenzene (TCNB) was measured after the irradiation with several hundred MeV of C, Ne and Ar ions. The absorbance due to the TCNB radical anion increased and then decreased with increasing the fluence for all ions. The fluence dependence of the absorbance was analyzed by use of the "chemical" track model with a cylindrical structure. As a result, the estimated radius of the chemical track decreases for C and Ne ions with increasing specific energy (ion energy per atomic mass unit). Furthermore, at the same specific energy, the radius increases with increasing ion mass. The formation yield (G-value) of the TCNB radical anion estimated by optical absorbance and ESR measurements was smaller than that by gamma-ray irradiation. (C) 2000 Elsevier Science Ltd. All rights reserved.