Investigating the effects of silicon tip contamination in noncontact scanning force microscopy SFM/

We have studied the possible modifications to a noncontact scanning force microscopy SFM.silicon tip due to adsorption of species from the gas phase and due to contact with a NaCl surface. A model of the tip was developed based on a 33 atom silicon cluster, and then the different adsorbates were added and changes to tip electrostatic properties investigated. The interaction of a silicon tip with a NaCl surface was modelled quantum mechanically, allowing us to calculate the charge state of the adsorbed chlorine ion in the process of separation of the two surfaces. q1999 Elsevier Science B.V. All rights reserved.