8 research outputs found
Anomalous interactions in confined charge-stabilized colloid
Charge-stabilized colloidal spheres dispersed in weak 1:1 electrolytes are
supposed to repel each other. Consequently, experimental evidence for anomalous
long-ranged like-charged attractions induced by geometric confinement inspired
a burst of activity. This has largely subsided because of nagging doubts
regarding the experiments' reliability and interpretation. We describe a new
class of thermodynamically self-consistent colloidal interaction measurements
that confirm the appearance of pairwise attractions among colloidal spheres
confined by one or two bounding walls. In addition to supporting previous
claims for this as-yet unexplained effect, these measurements also cast new
light on its mechanism.Comment: 8 pages, 5 figures, RevTeX4. Conference proceedings for CODEF-04,
Colloidal Dispersions in External Fields, March 29 - April 1, 200
Direct measurement of three-body interactions
Three-body interactions have been measured among three charged colloidal
particles in deionized solvent. Two of the particles have been confined to an
optical line-trap while the third one was approached by means of a focused
laser beam. The experimentally determined three-body interactions are
attractive and roughly of the same magnitude and range as the
pair-interactions. In addition, numerical calculations have been performed,
which show good agreement with the experimental results