The free positron lifetime in amorphous polymers at low temperature

Abstract

A series of amorphous polymers was studied by positron annihilation lifetime (PALS) spectroscopy at 20 K each experiment lasted more than 1 week. The lifetime spectra were deconvoluted into three exponential components. In isothermal conditions, an increase of the free positron lifetime is observed while the parapositronium (pPs) and orthopositronium (oPs) lifetimes do not change with the measuring time.