Investigation on three-photon absorption induced upconversion fluorescence properties of two fluorene-based derivatives

Steady state florescence and three-photon-absorption-induced upconversion fluorescence of two fluorene-based derivatives with different electron donors were investigated. The upconversion fluorescence intensity is cubic with the input intensity. The electron donors have great impact on the upconversion fluorescence property. The transition processes of the two molecules were investigated with TD SCF/DFT theory methods, the results of theory and experiments accord well with each other.