Molecular first hyperpolarizabilities of retinal and its derivatives

The hyper-Rayleigh scattering technique (HRS) has been used to determine the molecular first hyperpolarizabilities beta of retinal, retinoic acid, vitamin A acetate and a retinal Schiff base in its protonated and unprotonated form. The former is responsible for the linear and non linear optical properties of bacteriorhodopsin. PI, previous examination of these compounds by HRS at 1064 nm yielded surprisingly high p-values. Here, we report HRS measurements performed at 1064, 1300 and 1500 nm. The derived hyperpolarizabilities are self-consistent with the two-state model for all three wavelengths, but they are one order of magnitude lower than those reported previously. (C) 1997 Published by Elsevier Science B.V.