POSITRONIUM CHEMISTRY IN AQUEOUS KMNO4 SOLUTIONS

The reaction of positronium was studied in aqueous KMnO4 solutions at various concentrations and pK. Lifetime measurements show a distinct decrease of τ2 and increase of I2 with increasing temperatures, as expected for chemical reactions in which thermalized positronium is involved. No dependence on the pH of the solution could be observed. The activation energy calculated from the temperature dependence of τ2 is rather small and about 0.1-0.2 eV. The free positron annihilation lifetime was found to be approximately 0.55 nsec, which is in good agreement with the value obtained by using Dirac's formula, 0.5 nsec for water.