Photoconductivity in Anthracene Crystals Due to Excitation of Triplets

Two separate pulse-light sources, the first capable of producing singlets from which triplets are obtained by intersystem crossing, the second producing primarily a photon flux, have been used to produce a photocurrent in anthracene. An enhanced photocurrent is produced by the second flash well after the first flash has terminated. The decay of this effect appears to be characteristic of the lifetime of the triplets. The enhanced photoconductivity is believed to be a result of a tandem excitation process involving the triplets as the intermediate state.