Dynamics of Repulsing Charged Particles: a Fluorescence Cross-Correlation Spectroscopy Study

Electrostatic interaction controls the stability of charged colloidal particles dispensed in an aqueous solution. In our study, we measured the interaction between charged polystyrene particles by fluorescence cross-correlation spectroscopy (FCCS). Negative correlation function was observed for these repulsing particles and a detailed analysis by Brownian dynamics simulation provided a few important factors of the system: the correlation length at which the interaction dominates and the cage effect in the diffusion of the particles.