Form Contributions of Birefringence and Dichroism

Among the first theories of form birefringence was the calculation of Peterlin and Stuart [58] who solved for the anisotropy in the dielectric tensor of a spheroidal particle with different dielectric constants e j and e2 parallel and perpendicular to its symmetry axis, respectively. If the spheroid is aligned along the z axis, and resides in a fluid of dielectric constant e, the contribution of a single particle to the difference between the principal values of the macroscopic dielectric tensor of the fluid is 

It is important to note that the form effect is proportional to the square of the dielectric contrast, Ae, and will always be positive for prolate particles (Ll L2), and negative for oblate shapes (L2 Lx). The intrinsic contribution can change sign depending on the relative magnitudes of the principal values of the polarizability tensor of the particle. 

1 Theory of Copic for Form Birefringence of a Flexible Chain 

Equation (7.34) is the leading term in a near field expansion of the electric field generated from a radiating dipole. Substituting equations (7.34) and (7.33) into equation (7.32), and multiplying the result by the mean polarizability ot- of segment i, the following 

Equation (7.35) is a set of 3NK coupled linear equations that must be solved to 

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