title: Enhanced two-photon absorption and ultrafast dynamics of a new multibranched chromophore with a dibenzothiophene core.
abstract: A series of novel compounds with dibenzothiophene core branched structures have been synthesized, and their two-photon absorption (TPA) properties were investigated. Two-photon fluorescence (TPF) and z-scan techniques were carried out, and a significant enhancement in the TPA cross section was observed for ST-G2, which possesses the largest generation number among the studied samples. By using different solvents, the largest nonlinear optical (NLO) response was observed in the most polar solvent. Ultrafast pump-probe experiments were performed to probe the excited state dynamics in the branched molecules, and the obtained results further confirmed the TPA enhancement mechanism. Time-resolved fluorescence (TRFL) and TRFL anisotropy measurements reveal that there is an ultrafast charge localization to the intramolecular charge transfer (ICT) state followed by relaxation with a lifetime longer than 1 ns.
authors.affiliation: Physics Department, Fudan University, Shanghai 200433, People's Republic of China, Surface Physics Lab (National Key Lab), Fudan University, Shanghai 200433, People's Republic of China.
authors.forename: Yongli
authors.initials: Y
authors.lastname: Yan
authors.forename: Bo
authors.initials: B
authors.lastname: Li
authors.forename: Kangjun
authors.initials: K
authors.lastname: Liu
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Dong
authors.forename: Xiaomei
authors.initials: X
authors.lastname: Wang
authors.forename: Shixiong
authors.initials: S
authors.lastname: Qian