Bound Pairs: Direct Evidence for Long-range Attraction between Like-Charged Colloids
arXiv:0711.2883 · doi:10.1016/j.ssc.2008.06.026
Abstract
We report observations of stable bound pairs in very dilute deionized aqueous suspensions of highly charged polystyrene colloidal particles, with monovalent counterions, using a confocal laser scanning microscope. Through an analysis of several thousands of time series of confocal images recorded deep inside the bulk suspension, we find that the measured pair-potential, U(r) has a long-range attractive component with well depths larger than the thermal energy. These observations provide a direct and unequivocal evidence for the existence of long-range attraction in U(r) of like-charged colloidal particles.
8 pages, 4 figures, submitted to Phys. Rev. Lett