A simple method for the estimation of hyperpolarisabilities: Application to diamino substituted dicyanoquinodimethane molecules

Abstract

Two-level hyperpolarisabilities, /?2 of a series of amine substituted dicyanoquinodimethane molecules were investigated utilising a simple solvatochromic method developed by us for the determination of excited state dipole moments. The hyperpolarisability, as well as the two-level approximation to it, 2, of these quinonoid systems were estimated computationally. Using a parallel study on a set of well known coumarin dyes and their reported electric field induced second harmonic generation (EFISHG) for calibration, the experimental static /f s of quinonoid molecules are estimated and found to be very large, approximately in the range of - 50 to - 60 x 10~30 e.s.u.