CHEMICAL TRACKS OF HEAVY-IONS FOR 1,2,4,5-TETRACYANOBENZENE ANION-RADICAL FORMATION

Poly(vinyl alcohol) (PVA) film doped with 1,2,4,5-tetracyanobenzene (T CNB) was irradiated with 330 MeV Ar11+ and 220 MeV C5+ ions. Absorptio n bands observed in the 340-480 nm region after the irradiation are as cribed to TCNB anion radical, The absorbance of TCNB anion radicals in creased with increasing fluence, and reached at a maximum with fluence of the ions at 1.5 x 10(10) ions/cm(2) for Ar11+ ions and 6 x 10(10) ions/cm(2) for C5+ ions and then de creased, The increase and the decr ease of the absorbance indicate the formation and the consumption of T CNB anion radicals resulting from chemical reactions in the ''chemical track'' in which the chemical reaction is induced by a single ion aro und its trajectory. The fluence-yield curves were simulated with a cyl indrical track model. The radii of the chemical tracks have been estim ated to be 50 nm for Ar11+ ions and 20 nm for C5+ ions by curve fittin g of the fluence dependence, (C) 1998 Elsevier Science B.V.