We perform a molecular dynamics simulation to emulate the retraction followed by re-approach of an AFM with respect to a surface. We found a hysteresis in the snap-off distance and energy during such a tapping process of AFM tip. As the tip initially retracts from the surface, the meniscus gradually thins out and eventually snaps off. The meniscus keeps its symmetric shape during all stages of the retraction. On the other hand, as the tip re-approaches the surface, the water meniscus is initially asymmetric in shape but finally recovers its symmetry. The distance for the reformation of meniscus is about 4 nm shorter than the snap-off distance during tip retraction. Hysteresis also exists in the behavior of energy vs. tip-surface distance.
Journal: TechConnect Briefs
Volume: 3, Nanotechnology 2009: Biofuels, Renewable Energy, Coatings, Fluidics and Compact Modeling
Published: May 3, 2009
Pages: 296 - 299
Industry sector: Advanced Materials & Manufacturing
Topics: Informatics, Modeling & Simulation