Optical anisotropy of polypeptide chains

Optical anisotropies γ 2 of N‐t‐butylacetamide (tBA), N ‐Methylacetamide (MA), and N, N‐dimethylacetamide (DMA) have been determined from the Rayleigh ratios for depolarzed scattering by dilute solutions of the amides in p‐dioxane. Traceless optical polarizability tensors \documentclass{article}\pagestyle{empty}\begin{document}$ \widehat{\rm \alpha } $\end{document} for the amides are derived from these results in conjunction with the Kerr constant for tBA determined by LeGèvre and co‐workers. It is shown that the tensor \documentclass{article}\pagestyle{empty}\begin{document}$ \widehat{\rm \alpha } $\end{document} i for the glycyle unit in a polypeptide chain may be identified with \documentclass{article}\pagestyle{empty}\begin{document}$ \widehat{\rm \alpha } $\end{document} MA . Methods for deriving corresponding tensors for other peptide units are indicated and the traceless polarizability tensor \documentclass{article}\pagestyle{empty}\begin{document}$ \widehat{\rm \alpha } $\end{document} for a polypeptide chain in any specified configuration is formulated.