First-order hyperpolarizability of oligo-acene derivatives by hyper-Rayleigh scattering

First-order hyperpolarizabilities β for a series of oligo-acene derivatives were estimated as a function of the conjugation length by means of the hyper-Rayleigh scattering (HRS) technique. Satisfactory data acquisition and analyses gave the hyperpolarizabilities (17 ± 2) × 10−30 and (68 ± 8) × 10−30 esu for naphthalene-2,3-dialdehyde and anthracene-2,3-dialdehyde, respectively. The pure β value of tetracene-2,3-dialdehyde (OA4) could not be determined because of multiphoton absorption induced fluorescence superimposed on the HRS signal. A large β value (≈ 180 × 10−30 esu) is expected for OA4 by extrapolating the conjugation length dependence on β.