An approach for a polychromatic generalized Lorenz-Mie theory

In this work a polychromatic version of the generalized Lorenz-Mie theory stricto sensu (GLMT) is derived. In this new formalism, arbitrary time-dependent fields are expanded into partial waves using Bromwich scalar potentials and, instead of the usual expansion coefficients - the beam shape coefficients (BSCs) - found in the monochromatic GLMT, now one finds field shape spectra (FSSs) which are intrinsically frequency-dependent. Expressions for the incident, scattered and internal fields are presented, and it is shown how physical quantities defined and expressed in the monochromatic GLMT in terms of the BSCs are modified and redefined in terms of the FSSs in polychromatic light scattering problems, like scattered intensities and phase angles, absorption, extinction and scattering cross-sections, and radiation pressure cross-sections.