Optical limiting property and ultrafast pump-probe study of two X-shaped oligomers with anthracene unit as a core

Abstract

Two X-shaped multi-branched oligomers based on anthracene unit were studied by open-aperture Z-scan and ultrafast pump-probe methods to elucidate the nonlinear optical absorption properties as well as intramolecular charge transfer properties of typical X-shaped oligomers. Significant enhancement on the nonlinear optical absorption property was observed for the oligomer with triphenylamine groups as terminal end of each branch. Obvious optical limiting property was observed for these X-shaped oligomers and the mechanism was attributed to the two-photon absorption process. The ultrafast dynamic of these X-shaped oligomers exhibited a fast process about several ps to build an intramolecular charge transfer state, followed by a slow process longer than 100 ps which reflecting the evolution of the intramolecular charge transfer state.