ADHESION OF SMALL PARTICLES IN ELECTRIC-FIELDS

We discuss experiments performed with an atomic force microscope that has been modified so that an electric field can be applied across a di electric particle attached to a cantilever. The modified microscope is used to measure the attractive (before contact) and adhesion (after c ontact) forces for micrometer-sized dielectric particles. From these m easurements, the relative contributions of the nonelectrostatic forces and the electrostatic forces to adhesion can be quantified. Surface c onductivity is observed to change the particle's attraction to the sur face. In large electric fields, the electrostatic forces dominate the particle's adhesion.