The changes of o-Ps intensity in benzene and cyclohexane solutions in the presence of different concentrations of electron scavenger (CCl4) and positive hole scavenger (pyridine) have been investigated. The results show that both the mobilities of electron and positive ion in cyclohexane are very high. Their mobilities in benzene are also high but less than that in cyclohexane. The fitting equation for the enhancement of o-Ps intensity in the presence of hole scavenger was derived, and shows that enhancement or inhibition of o-Ps intensity is the consequence of competition between processes of scavenging election and scavenging positive ion.

Key words: BENZENE, CARBON TETRACHLORIDE, PYRIDINE, ANNIHILATIONS, CYCLOHEXANE, POSITRONIUM, ELECTRON MOBILITY