We study the interrelation of the internal field of irregular particles to the far-field scattering characteristics by modifying the internal field of dipole groups. In this paper, we concentrate on the longitudinal component, i.e., the internal-field component parallel to the incident wave vector. We use the discrete-dipole approximation to determine the internal field and switch off the longitudinal component from the dipoles that have the highest energy density above a preset cutoff value. We conclude that only a relatively small number of core dipoles, about 5% of all dipoles, contribute to the negative linear polarization at intermediate scattering angles. These core dipole groups are located at the forward part of the particles. The number of core dipoles in the group becomes greater as particle asphericity increases. We find that the interference between the scattered waves from the core dipole groups, which was studied previously for spherical particles, is preserved to a large extent for nonspherical particles.
© 2010 Optical Society of America
Original Manuscript: April 26, 2010
Revised Manuscript: August 23, 2010
Manuscript Accepted: August 23, 2010
Published: September 23, 2010
Jani Tyynelä, Evgenij Zubko, Karri Muinonen, and Gorden Videen, "Interpretation of single-particle negative polarization at intermediate scattering angles," Appl. Opt. 49, 5284-5296 (2010)