Angle dependent light scattering by highly uniform colloidal rod-shaped microparticles: experiment and simulation

Abstract

While extensive theoretical work has been devoted to analyzing scattering behavior for nonspherical particles, few experimental studies of the light-scattering properties of such particles are available, largely because of the difficulty of synthesizing such particles with uniform geometries. Here we report the synthesis of highly uniform, volume-equivalent rod-shaped colloidal particles prepared from their commercial spherical counterparts, on which we performed light scattering experiments as a function of scattering angle for micro rods with varying aspect ratio and volume. These results were compared to values calculated using the T-Matrix method. Good agreement with theoretical predictions was found for the experimentally measured scattering cross sections and the angular dependence of the scattering intensity. An increase in the forward scattering intensity is observed and predicted for particles with larger aspect ratios relative to their volume equivalent spheres, with only minor differences observed at both mid-range and backscattering angles. Furthermore, the light scattering results for the rod-shaped particles did not show the scattering fringes seen in scattering by the spheres, indicating that as three-dimensional symmetry is broken, the associated Lorenz–Mie resonances are strongly attenuated.