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Positronium trapping process caused by slow thermalization of Ps inside intermolecular spaces of polymer is considered. The pickoff annihilation rate of Ps decreases from an initial value, characteristic for the delocalized Ps, to a final value, relating to its localized state. The elastic thermalization lifetime analysis of polymers spectra with a new ETLT program is proposed to determine the total...
The dependence of free volume on temperature has been monitored in some cross-linked polyurethanes, with different chain lengths, by using positron annihilation lifetime spectroscopy (PALS). The spectra were analysed in terms of continuous distributions in order to obtain the distribution of the longest component, τ 3 . The relative number and the mean size of free volume holes have been...
A new model is presented describing the annihilation of positronium in polymers. Ps is formed in the bulk and is trapped into the free volume holes with epithermal initial energy where it thermalizes towards its ground state. This model was verified by interpreting lifetime spectra in an amorphous cross-linked polyurethane.
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