where [DELTA][alpha] is anisotropy of molecular polarizability
, [mu] is the resultant dipole moment of the molecule, N is the molecular number density, [DELTA][alpha] is dielectric anisotropy, F is parameter depending on reaction field factor, and [beta] is the angle between the molecular axis and the direction of the off axis.
where [DELTA]C is the change of nuclear coordinate, [alpha] the molecular polarizability
(taken as 10[[Angstrom].
The enhancement is in part attributed to an exceptional increase in the local electromagnetic field (the "electromagnetic mechanism") and to an increase in the molecular polarizability
(the "chemical" or "charge transfer mechanism").
In solutions and melts, where the stresses originate from entropy elasticity, this coefficient scales with the anisotropy of the molecular polarizability of the polymer chain, [DELTA][alpha] (14, 15), as expressed in Eq 2.
For the stress-optical behavior in the glass state at small strains the relation to the molecular polarizability is less well understood, although a correlation to [DELTA][alpha] has been suggested (17, 18).
FB-PC also has a negative molecular polarizability very much like SBI-PC.
The software was slightly modified in-house to allow calculation of the imaginary molecular polarizability function [Phi] from the n and k spectra.
The molecular polarizability spectra obtained from the reflectance spectra are shown in Fig.