Circular intensity differential scattering of light by helical structures. I. Theory

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Abstract
General expressions for the fields and intensities of scattered electromagnetic radiation by helical structures whose optical properties are described by a uniaxial polarizability along the tangent to the helix are obtained. Analytical expressions for the circular intensity differential of scattering (CIDS) as a function of the helix parameters and the wavelength of light are derived. It is shown that a sufficient condition for the existence of differential scattering for right and left circularly polarized light is the existence of an asymmetric polarizability. The choice of a uniaxial polarizability is found to give rise to form CIDS. For incident plane‐polarized light, the scattered fields are found to be generally elliptically polarized. The Stokes parameters describing the state of polarization of the scattered radiation are derived. These results are expected to be relevant both as a new method to characterize chiral regions in macromolecular structures as well as to describe the light scattering properties of cholesteric and twisted nematic liquid crystals. The theory can also describe the radiation modes of helical antennas.