Characterization of Internal Particle Structures by Dynamic Light Scattering

Abstract

Available dynamic light scattering (DLS) methods determine only the size and surface charge of the particles since information is obtained from an analysis of the motion arising from thermal noise or electrophoretic force. We propose a new method combining DLS with dielectric single particle spectroscopy [GIMSA et. al. 1995]. This method exploits the fact that also ac-fields of the radio frequency range may induce particle motion. In such fields the particle’s polarization is a function of field frequency. Depending on the external field properties translation (dielectrophoresis) or rotation (electrorotation) may be induced. In electrorotation the dielectric properties of particles subject to a rotating electric field may be obtained from the frequency spectrum of individual particle rotation. Given a known geometry, dielectric constants and conductances of the particle’s substructures can be obtained from the electrorotation spectrum.