title: Single scattering by a small volume element.
abstract: Starting from first principles, we present a detailed analysis of the concept of single scattering of light by a small volume element filled with sparsely and randomly positioned particles. We first derive the formulas of the far-field single-scattering approximation, which treats the volume element as a single scatterer, and discuss its range of applicability, using for illustration exact T-matrix results for randomly oriented two-sphere clusters. Our second approach is to treat the volume element as a small cloud of particles and apply the so-called first-order-scattering approximation. We demonstrate that although the two approaches are based on somewhat different sets of assumptions, they give essentially the same result for the electromagnetic response of a sufficiently distant polarization-sensitive detector.
authors.affiliation: NASA Goddard Institute for Space Studies, 2880 Broadway, New York, New York 10025, USA. crmim@giss.nasa.gov
authors.forename: Michael I
authors.initials: MI
authors.lastname: Mishchenko
authors.forename: Joop W
authors.initials: JW
authors.lastname: Hovenier
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Mackowski