SEARCH Articles Figures Tables Cascade-free lifetime measurements Free Volume Model and Positronium Lifetime Connection Free radical lifetimes Free radicals, absorption spectra lifetime Free volume positron annihilation lifetime spectroscopy Lifetime free positron Lifetime free volume distribution Positron annihilation lifetime spectroscopy PALS), free volume Positron annihilation lifetime spectroscopy free volume polymers Positron annihilation lifetime spectroscopy high free volume polymers