Europhys. Lett.
Volume 75, Number 1, July 2006
Page(s) 174 - 180
Section Interdisciplinary physics and related areas of science and technology
Published online 26 May 2006
Europhys. Lett., 75 (1), pp. 174-180 (2006)
DOI: 10.1209/epl/i2006-10065-1

Effective forces between colloids at interfaces induced by capillary wavelike fluctuations

H. Lehle, M. Oettel and S. Dietrich

Max-Planck-Institut für Metallforschung - Heisenbergstr. 3 D-70569 Stuttgart, Germany and Institut für Theoretische und Angewandte Physik, Universität Stuttgart Pfaffenwaldring 57, D-70569 Stuttgart, Germany

received 13 February 2006; accepted in final form 29 April 2006
published online 26 May 2006

We calculate the effective force mediated by thermally excited capillary waves between spherical or disklike colloids trapped at a fluid interface. This Casimir type interaction is shown to depend sensitively on the boundary conditions imposed at the three-phase contact line. For large distances between the colloids an unexpected cancellation of attractive and repulsive contributions is observed leading to a fluctuation force which decays algebraically very rapidly. For small separations the resulting force is rather strong and it may play an important role in two-dimensional colloid aggregation if direct van der Waals forces are weak.

82.70.Dd - Colloids.
68.03.Kn - Dynamics (capillary waves).

© EDP Sciences 2006