A SIMPLE METHOD FOR THE ESTIMATION OF HYPERPOLARIZABILITIES - APPLICATION TO DIAMINO SUBSTITUTED DICYANOQUINODIMETHANE MOLECULES

Two-level hyperpolarisabilities, beta(2) of a series of amine substitu ted dicyanoquinodimethane molecules were investigated utilising a simp le solvatochromic method developed by us for the determination of exci ted state dipole moments. The hyperpolarisability, beta as well as the two-level approximation to it, beta(2), of these quinonoid systems we re estimated computationally. Using a parallel study on a set of well known coumarin dyes and their reported electric field induced second h armonic generation (EFISHG) beta for calibration, the experimental sta tic beta's of quinonoid molecules are estimated and found to be very l arge, approximately in the range of - 50 to - 60 x 10(-30) e.s.u.