Abstract
We report the fluorescence upconversion properties of a class of improved pyridinium toluene- p-sulfonates having donor– π–acceptor (D– π–A) structure under two-photon excitation at 1064 nm. The experimental results show that both the two-photon excited (TPE) fluorescence lifetime and the two-photon pumped (TPP) energy upconversion efficiency were increased with the enhancement of electron-donating capability of the donor in the molecule. It is also indicated that an overlong alkyl group tends to result in a weakened molecular conjugation, leading to a decreased two-photon absorption (TPA) cross section. By choosing the donor, we can obtain a longest fluorescence lifetime of 837 ps, a highest energy upconversion efficiency of ∼6.1%, and a maximum TPA cross-section of 8.74×10 −48 cm 4 s/photon in these dyes.
Published Version
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