Positronium-oxygen interaction in hexane

The role played by the O2molecule in the decay of Ps in air-saturated hexane was investigated by measurements of lifetime and by an experiment of magnetic quenching. The results indicate that a) O2reduces the overlap probability |φ(O)|2of the interacting positron-electron pair in Ps by a factor 1.6, b) Ps may react with the O2molecule forming a short-lived compound with a rate constant kq=5.7·10−11cm3s−1and c) it may undergo exchange collisions with unpaired electrons of the O2molecule with a rate constant γq= cm3s−1.