Two-photon absorption in quadrupolar bis(acceptor)-terminated chromophores with electron-rich bis(heterocycle)vinylene bridges

Two-photon absorption spectra for a range of bis(acceptor)-substituted bis(dibutoxythienyl)ethene and bis(N-hexylpyrrolyl)ethene chromophores have been recorded using Z-scan and white-light-continuum pump-probe techniques. All the chromophores studied show strong near-infrared two-photon absorption with cross sections in the range of 2400-5900 GM (1 GM = 1 x 10(-50) cm(4) s/photon) at photon wavelengths between 1.0 and 1.3 mu m; cross sections as high as 10000 GM can be accessed close to the one-photon absorption edge. Quantum-chemical calculations reproduce the experimentally observed variations of the two-photon properties with the chemical structure.