Diffusion coefficients of positronium in amorphous polymers

Abstract

Diffusion coefficients of positronium (Ps) have been determined for polysulfone (PSF), polycarbonate (PC) and polystyrene (PS) by means of positron lifetime spectroscopy. 2,2′-Dinitrobiphenyl (DNB) was added to the polymers as a Ps quencher, and the diffusion coefficients were determined from measured Ps quenching rate constants, assuming that the reaction between Ps and DNB was diffusion controlled. It is shown that the diffusion coefficients of Ps at 25 °C are (2.6–3.2)× 10^–6 cm² s^–1, two–three orders of magnitude larger than those of oxygen, nitrogen and argon. The effect of DNB on Ps formation is briefly discussed.