Inhibition of positronium formation and its quenching reactions in binary solid solutions and mixtures of metal tris-2,2,6,6-tetramethyl-3,5-heptanedionate (dpm) complexes

The inhibition of positronium formation and its quenching reactions have been studied in binary solid solutions formed by Al(dpm)3 as a matrix, and Co(dpm)3, Fe(dpm)3 and Mn(dpm)3 as guest molecules, by lifetime and Doppler broadening spectroscopies. In all the solid solutions studied the quenching of positronium lifetime by redox reactions was observed. The total inhibition and quenching rate constants determined for each system are similar. The full-width at half-maximum of the annihilation line increases with increasing guest molecule mole fraction, indicating the presence of redox reactions combining with inhibition processes. The corresponding mixtures were studied as blanks.