POSITRONIUM-OXYGEN INTERACTIONS IN POLYTRIMETHYLSILYLPROPINE MEMBRANES

The shortening of tripler positronium (Ps) lifetime by oxygen in membr anes of polytrimethylsilylpropine has been studied by using the lifeti me spectroscopy and the Zeeman effect on Ps: the mixing of the m = 0 P s sublevels induced by the magnetic held produces a quenching of ortho -Ps lifetime, which can be used to discriminate between the chemical r eactions of Ps by oxygen (ortho-para conversion or oxidation). Our dat a can be interpreted in terms of an ortho-para conversion; the reactio n of Ps oxidation is negligible for the system trapped in the holes fo rming the free volume of the membrane.