LOW-FIELD EXPRESSIONS FOR REVERSING-PULSE ELECTRIC BIREFRINGENCE OF IONIZED POLYIONS WITH PERMANENT, IONIC, AND ELECTRONIC DIPOLE-MOMENTS -A FURTHER EXTENSION OF THE ION-FLUCTUATION THEORY AND THE APPLICATIONTO POLY(ALPHA,L-GLUTAMIC ACID)

A rigorous theory was further extended for the reversing-pulse electri c birefringence (RPEB) of the ionized polyion of cylindrical symmetry with the permanent dipole moment mu(3), in addition to two previously considered electric dipole moments, i.e., the root-mean-square-average moment (m(3)(2))(1/2) resulting front the fluctuation of ion-atmosphe re along the longitudinal (3)axis of the polyion with a single relaxat ion time tau(I), as originally proposed by Szabo et al. [J. Chem. Phys . 85, 7472 (1986)], and the electronic moment from the intrinsic coval ent polarizability anisotropy Delta alpha between the longitudinal and transverse axes of the polyion by Yamaoka et nl, [J. Chem. Phys. 101, 1625 (1994)]. The extended RPEB expressions were derived with three e lectric and hydrodynamic parameters (p = mu(3)(2)/kT Delta alpha, q = [m(3)(2)](1/2)/kT Delta alpha, and tau = tau(l)/tau(theta)) in the Ke rr-law region. Calculated with appropriate values to these parameters, the theoretical curves show such new features that either maxima or m inima appear in the buildup and reverse processes. The present theory was used to analyze a set of experimental RPEB signals of poly(alpha,L -glutamic acid) in helical conformation in methanol and in methanol-wa ter containing sodium hydroxide, By fitting the observed data to theor etical curves, the contribution of [m(3)(2)](1/2) was shown to surpass that of mu(3) for the same helical sample that was partially ionized by neutralization with sodium hydroxide. (C) 1996 American Institute o f Physics.