TIP-SURFACE INTERACTIONS STUDIED USING A FORCE CONTROLLED ATOMIC-FORCE MICROSCOPE IN ULTRAHIGH-VACUUM

A magnetic force has been used to control a partially magnetized atomi c force microscope cantilever in ultrahigh vacuum in order to investig ate tip-surface interactions. It is shown that farces applied by an os cillating tip can drastically affect the measured response of the leve r. In particular the oscillating force influences the measured tip-sur face adhesion and can be treated as a simple addition to the static ap plied force in breaking adhesive bonds. Qualitative differences in far ce spectroscopy measurements due to the amplitude of the driving oscil lation of the lever are presented and an alternative nonintrusive tech nique introduced. (C) 1997 American Institute of Physics.