Hyperpolarisability of (donor)2-acceptor-type molecules determined by EFISHG

Molecular first-order hyperpolarisabilities β of (donor)2-acceptor type molecules have been determined by electric field induced second-harmonic generation (EFISHG) experiments at 1.06 μm. The hyperpolarisability values are enhanced in these two dimensional charge transfer molecules, compared with a reference linear model molecule. One of these molecules absorbs part of the second-harmonic beam. We propose a determination method for β that takes into account this phenomenon. Crystals of the title molecules exhibit second harmonic generation by the powder test.