Jn. Woodford et al., Dispersion of the first molecular hyperpolarizability of charge-transfer chromophores studied by hyper-Rayleigh scattering, CHEM PHYS, 271(1-2), 2001, pp. 137-143
Stimulated Raman scattering from pressurized CH4 gas confined in a Raman sh
ifter is employed to obtain an excitation wavelength at 1543 nm for the hyp
er-Rayleigh scattering (HRS) experiment. The first molecular hyperpolarizab
ilities (ss) of a series of thiophene-based organic chromophores are determ
ined using this excitation wavelength to help shed light on their frequency
dependence. By combining the HRS results at 1543 nm with those using the 1
907 and 1064 rim excitation previously obtained, we arrive at an unambiguou
s result about the intrinsic hyperpolarizability calculated from the ss val
ues at these two wavelengths. The results are interpreted using an extended
two-state model previously put forth by our laboratory. The extended model
that includes the vibration and damping in the hyperpolarizability express
ion is intended for interpreting HRS data obtained using excitation wavelen
gth in the resonance regime. (C) 2001 Published by Elsevier Science B.V.