ON THE ORIGIN OF THE INTERMEDIATE COMPONENT IN THE POSITRON LIFETIME SPECTRA IN POLYMERS

We have carried out an investigation of the nature of the ≈1 ns intermediate component in the positron time annihilation spectra of five polymers (atactic and isotactic polypropylene, polymethylmethacrylate, teflon, and polyethylene), using the magnetic quenching technique at high fields (1.5-3 T), coupled to lifetime spectroscopy. The results indicate that this component comes from the decay of a positron-electron bound system, different from that associated with the longest lifetime component. Therefore, two different Ps-like systems must be considered in the investigated polymers. © 1990 Springer-Verlag.