On the involvement of geminate pairs in radiation-induced conductivity of polystyrene
A. P. Tyutnev, J. Kundin, V. R. Nikitenko, V. S. Saenko, E. D. Pozhidaev.
High Energy Chemistry, 35, 79-86, (2001)
Basic parameters of the generalized Rose-Fowler-Weisberg theory were experimentally determined for polystyrene. The obtained data were used to comprehensively analyze the evolution of geminate pairs in this polymer. It was shown that the generation of the prompt component of radiation-induced conductivity occurs by the trapping mechanism with two charge carrier states involved, the quasi-free and trapped. This generation under equilibrium transport conditions (diffusivity and mobility of carriers are constant) reportedly ensured by the geminate recombination itself was not observed in a real experiment. With allowance for dispersive transport of holes (the major carriers), the lifetime of geminate pairs were found to be as long as a few hundred of milliseconds at 300 K. The published data on the formation and decay kinetics in doped polystyrene upon its pulse radiolysis or photolysis were thoroughly analyzed. It was shown that, at ultrashort times before localization of generated carriers, the contribution of electrons to the observed conductivity prevails, although the basic contribution is made by holes in later times.
Keyword(s): conductance; diffusion; dispersion; electron; photolysis; radiation; radiochemistry; radiolysis; transport kinetics