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A non-conventional method of polymer PAL spectrum analysis by the LT computer program
Institution:1. Center for Biomolecular Nanotechnologies @UNILE, Istituto Italiano di Tecnologia, Via Barsanti 1, 73010 Arnesano, LE, Italy;2. NNL-CNR Istituto di Nanoscienze, Via per Arnesano, 73100 Lecce, Italy;3. IPCF-CNR UOS di Pisa, Via G. Moruzzi 1, 56124 Pisa, Italy;4. IC-CNR Istituto di Cristallografia, Via Amendola 122/O, 70126 Bari, Italy;5. Dipartimento di Matematica e Fisica ‘E. De Giorgi’, Università del Salento, Via per Arnesano, 73100 Lecce, Italy
Abstract: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.
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