Laser Light Scattering by Poly-α-amino Acid Solutions

An improved self-beat spectrometer has been used to study the spectrum of light, from a He–Ne laser, scattered by solutions of poly-γ-benzyl-l-glutamate (PBG). From the observed spectral broadening, the translation diffusion constants of the solvated polymer were calculated. Diffusion constants were measured also as a function of solvent composition. A change in the diffusion constant at about 76% dichloroacetic acid (at 25°C) reflected the well-known helix–coil transition of PBG.