Abstract
AbstractThe increase of the positronium (Ps) yield as a function of the positron (e+) source exposure time at 20 K was monitored in polypropylene and polystyrene by positron annihilation lifetime (PAL) and Doppler broadening (DB) spectroscopy. The contributions of the different e+ and Ps states as extracted from the PAL analysis were used to reproduce the behaviour of the sharpness parameter (S) as a function of the wing parameter (W) of the annihilation line as measured by DB spectroscopy. We find a remarkable non‐linearity in the S ‐W plots, which seems to be related to the existence of a third component (C3) in a four‐component exponential analysis. We discuss the origin of C3 in the frame of a “blob” analysis of the PAL spectra. It is shown that the simulated S‐W dependence can satisfactorily fit the observed non‐linearity only on the assumption that C3 characterizes a e+‐molecule complex. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
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