FIRST-ORDER HYPERPOLARIZABILITY OF OLIGO-ACENE DERIVATIVES BY HYPER-RAYLEIGH SCATTERING

First-order hyperpolarizabilities beta for a series of oligo-acene der ivatives were estimated as a function of the conjugation length by mea ns of the hyper-Rayleigh scattering (HRS) technique. Satisfactory data acquisition and analyses gave the hyperpolarizabilities (17 +/- 2)X 1 0(-30) and (68 +/- 8) x 10(-30) esu for naphthalene-2,3-dialdehyde and anthracene-2,3-dialdehyde, respectively. The pure beta value of tetra cene-2,3-dialdehyde (OA4) could not be determined because of multiphot on absorption induced fluorescence superimposed on the HRS signal. A l arge beta value (approximate to 180 x 10(-30) esu) is expected for OA4 by extrapolating the conjugation length dependence on beta. (C) 1997 Elsevier Science B,V.