Activation mechanisms of recombination processes in irradiated poly(arylenephthalides)

Abstract

The recombination of separated ion-radical states (SIRS) in poly(arylenephthalide) (PAPh) films accompanied by emission of light with a maximum of ∼ 500 nm has been analyzed. The density functional theory methods [PBE1PBE/6-311+G(d,p)] and mathematical modeling were used for description of thermally stimulated luminescence (TSL) kinetics of PAPh. The versatility of the earlier proposed three-step kinetic model of metastable (X) and labile (Y) SIRS recombination was demonstrated on the example of various cardo polymers. The contribution of X-SIRS recombination to total luminescence was found to be characterized by the vanishingly small intensity in a vacuum and moderate and maximum one in inert gases and an oxygen-containing medium, respectively. It was found out that the recombination of labile SIRS does not depend on the nature of the atmosphere. It was theoretically substantiated that SIRS recombination can proceed via the transfer of both positive and negative charges. It was shown that the key factor determining the efficiency of thermal activation of recombination processes is the ratio of radiant and conductive channels of energy transfer from the heating element to the polymer sample.