Positron annihilation spectroscopy study of polymers and organic liquids

We have used positron annihilation Doppler broadening spectroscopy and positron annihilation lifetime spectroscopy to investigate properties of several polymers and organic liquids. The Doppler broadening is characterized by the $S$ parameter, which is a measure of the probability of low momentum annihilations in the material. The lifetime spectroscopy is characterized by the ortho-positronium (o-Ps) lifetime and intensity of o-Ps formation. We found that the correlation between the S parameter and the probability of o-Ps formation is dependent on polymer composition and sensitive to oxygen or fluorine present in the polymer. A similar conclusion has also been recently reported by another group.[1] We also found correlations between our results and various physical parameters characterizing the materials. \newline \newline [1] K. Sato, et al, Phys. Rev. B 71, 012201 (2005).