Frequency-dependent first hyperpolarizabilities from linear absorption spectra

摘要

The first hyperpolarizabilities (beta) of donor-acceptor-substituted push-pull molecules are generally described by a model in which the lowest excited electronic state dominates the optical response. It is shown that within the usual assumptions accompanying this two-state model, beta(-2omega; omega, omega) can be expressed in terms of a Kramers-Kronig transform of the linear optical absorption spectrum. The method is applied to p-nitroaniline and several other push-pull chromophores, and results are compared with experimental data where available. Comparison of calculated and measured frequency dispersions is suggested as a purely experimental method, requiring no additional parameters, to test the assumptions of the two-state model. (C) 2002 Optical Society of America. [References: 58]