Abstract

Herein, we present a practical yet accurate dispersion model for the molecular first hyperpolarizability β. This model incorporates both homogeneous and inhomogeneous line-broadening, because these affect the β dispersion differently, even if indistinguishable in linear absorption. Consequently, combining the absorption spectrum with one free shape-determining parameter G_inhom, the inhomogeneous linewidth, turns out to be necessary and sufficient to obtain a reliable description of the β dispersion, requiring no information on the homogeneous (including vibronic) and inhomogeneous line-broadening mechanisms involved, providing an ideal model for practical use in extrapolating experimental nonlinear optical (NLO) data. The model is successfully applied to extensive wavelength-dependent hyper-Rayleigh scattering (HRS) data of the efficient NLO chromophore picolinium quinodimethane (PQDM).

© 2012 Optical Society of America