A non-conventional method of polymer PAL spectrum analysis by the LT computer program

A new version of computer program (LT v.10) offers a new concept of polymer spectrum analysis. The theoretical model takes into account a few processes in which positron is involved: the process of slow formation and localization of positronium (Ps), delay formation of positronium from shallow trapped electrons and positron trapping in irradiation-induced centers. The model was applied to two series of spectra for LDPE and HDPE collected at constant temperature (much below the glass temperature) as a function of measurement time. The Ps internal relaxation time and time of localization of Ps in a free-volume center were determined. The results show that the trapping rate of positron is strictly correlated with the amount of the shallow trapped electrons. That suggests a coupling between the positron and electron-trapping centers.