The two photon laser photolysis of pyrene in alkanes, benzene and methanol have been studied. Initial excitation of pyrene leads to the first excited singlet state, which subsequently absorbs a second photon leading to photoionization. Detection of the photoionization level at 10−9 sec time intervals indicates a very small photoionization yield in alkanes compared to alcohols. It is shown that this is due to a rapid initial neutralization of the photoproduced ions in the alkane, and that the initial yields of two photon photoionization are comparable in alkanes and alcohols. The lifetimes of the ion neutralization are 6.7×10−10 sec in methanol, 2×10−12 sec in iso‐octane, 2×10−11 sec in hexane and 6.7×10−12 sec in benzene.

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