OPTICAL ANISOTROPIES OF NEMATOGENS FROM THE DEPOLARIZED RAYLEIGH SPECTRA

Depolarized Rayleigh spectra recorded with a planar Fabry-Perot interferometer have been used to determine the intrinsic optical anisotropy γ2 oligomers of several p-oxybenzoate oligomers and several solvents. The VH (V, vertical; H, horizontal) spectrum of benzene was used as a standard with the absolute Rayleigh ratio RVH(25°C) = 2.67 × 10-6 cm-1 at 488 nm. The broad collision-induced background can be excluded since the Fabry-Perot interferometry allows the determination of the much narrower Lorentzian line of the depolarized spectra that contains the molecular anisotropy γ2. The constitutive scheme for construction of the anisotropy of the molecular polarizability tensor with the group increments is in agreement with the experimental γ2 of the oligomers. This corroborates the notion that measurements of γ2 are highly useful for determination of conformational parameters. © 1990 American Chemical Society.