Morphological resonances detected from a cluster of two microspheres

Abstract

Morphological resonances are detected in elastic scattering and fluorescence excitation spectra from a cluster of two spheres, each ~5 μm in radius, isolated and oriented in an electrodynamic levitator trap. Light scattering at 90° and perpendicular to the line of centers of the particles, by broadside illumination with polarization in the scattering plane, shows that an independent particle model may be used in describing resonance positions and the shape of the spectrum, even though the joined particles differ in size by slightly less than 10 nm. In end-fire illumination the fluorescence excitation spectrum is missing a number of resonances that are seen with broadside illumination.