Effect of oxygen on the lifetime of O-Ps in perfluorobezene

Under examination of the effect of oxygen on the lifetime (τ3) of ortho-positronium (O-Ps) in perfluorobenzene system, it is found that the effect of oxygen on (τ3 in C6F6 is not marked when Po2 is less than 9.3 x 103 Pa, but the τ3 is decreased markedly as Po2 increases. The experimental results show that the effect of excited molecule 3(C6F6)* on the τ3 of OPs is small. The values of the original pick-off lifetime (τ30) of O-Ps, K(3O2 + O-Ps), and K(3(C6F6)* + O-Ps) have been found to be 4.15 ns, 1.8 x 101) (1 centre dot mol-1 centre dot s-1) and 1.7 x 1010 (1 centre dot mol-1 centre dot s-1), respectively