Force gradient versus distance curves studied by atomic force microscopy

Force gradients between silicon tips and (110) Si surfaces have been measured in Ar controlled atmosphere by means of an Atomic Force Microscope. Noncontact mode techniques have been exploited to investigate long range Van der Waals forces without the influence of meniscus forces. Measurements have been compared to the theoretical predictions for the induced dipole-dipole contribution. Theoretical curves need to be corrected for finite oscillation amplitude effects.