Effects of two-photon fluorescence and polymerization on the first hyperpolarizability of an azobenzene dye

The technique of hyper-Rayleigh scattering (HRS) has been employed to investigate the first hyperpolarizability (beta) of the azo dye Disperse Red 19 and a polymer in which Disperse Red 19 appears as a side-chain moiety. In addition to HRS, these two molecules were found to exhibit substantial two-photon-induced fluorescence (TPF). The TPF spectra for these molecules were measured, and corrected HRS intensities were obtained. Using an external reference method, beta values of (1480 +/- 100) x 10(-30) and (1470 +/- 90) x 10(-30) esu were determined for the dye and polymer systems, respectively, in dimethyl sulfoxide at 1064 nm. The difference between these two values is very small and shows that the effect of polymerization on the HRS intensity, in the dilute concentration limit, is negligible.