Electric dichroism studies: interaction of trifluoroacetic acid with poly (gamma-benzyl L-glutamate)

Theoretical approach to the measurement of the induced linear dichroism of rigid macromolecules

A comprehensive theory is developed in terms of the principal molar extinction coefficients (epsilon(ii)) of rigid, isolated, rodlike macromolecules when subjected to orienting force fields. The theory embraces the conventional transverse parallel and perpendicular arrangements and the novel longitudinal dichroism method where the light beam and applied field traverse the system concomitantly. Both transverse and longitudinal measurements are considered when the initial light beam. is unpolarized. It is shown that unpolarized light yields as much molecular information as the polarized methods used hitherto. Equations also are given in terms of a single repeating chromophore (epsilon(0)) as if at a specific direction (alpha) to the molecular backbone.

Simple apparatus for pulsed electric dichroism measurements

A novel method of measuring the electrically induced dichroism of macromolecular solutions is described. Transient changes in the solution absorption are recorded when the solute molecules are aligned by pulsed electric fields that are applied along the incident path. Previous methods have applied fields transverse to the optical beam which has had to be variably polarized. The present longitudinal arrangement needs no polarizer, is simpler, can yield the required information in a single suitable measurement, and has other distinct advantages over the former transverse arrangements. The theory for the effect is derived, and the interrelation of these novel longitudinal measurements with the conventional transverse data is verified by measurements on an aqueous solution of the amylose triiodide complex.