Hyper-Rayleigh scattering of thiophene-incorporated polyene chromophores with π-configuration locking

The hyper-Rayleigh scattering (HRS) technique is used to determined and compare the first hyperpolarizabilities (β) of thiophene-incorporated polyene chromophores with and without a configuration locked trans-triene bridge. To ensure the purity of the HRS signal, special attention is paid to its dependence on the fundamental intensity and the spectral content of the scattered radiation including the two-photon absorption induced fluorescence. From the HRS results, it is found that the configuration-locked trans-triene bridge enhances the β values of the chromophores studied. The β-enhancement is more pronounced when the electron acceptor CHCC(CN)2 in the chromophores is replaced with C2(CN)3.