Two-color, photon-gated spectral hole-burning in an organic material

We report the first observation of two-color, photon-gated spectral hole-burning in an organic system: carbazole in boric acid glass. This novel hole-burning mechanism involves stepwise biphotonic photoionization of carbazole at 1.4 K. The quantum yield for photoionization increases exponentially with the energy of the second photon. © 1985.