Enhancement of Two-photon Absorption by Ce~(3+) Sensitization in Organic Dyes

摘要

The two-photon absorption (TPA) and TPA-induced frequency upconversion emission properties of the dyes 4-[P-(dicyanoethylamino) crystal ]-N-methypyrdinium iodide and the complex of 4-[ P-(dicyanoethylamino) crystal] -N-methypyrdinium iodide and Ce(NO_3)_3 were experimentally studied. It was found that the TPA cross section for the dye sensitized by Ce~(3+) is two factors larger than that of the dye without being sensitized. A three-level system model of the dye molecules was used to analyze the enhancement of TPA by the sensitizer Ce~(3+) , which indicated that the sensitizer results in the increase of the transition dipole moment from the one-photon allowed excited state(1Bu) to the two-photon allowed excited state(2Ag).