AVS 47th International Symposium
    Surface Science Wednesday Sessions
       Session SS-WeP

Paper SS-WeP12
W-Si(111) Force Interaction Measurements with Force-feedback Force Sensor

Wednesday, October 4, 2000, 11:00 am, Room Exhibit Hall C & D

Session: Poster Session
Presenter: V. Yakimov, McGill University, Canada
Authors: R. Erlandsson, Linkoping University, Sweden
V. Yakimov, McGill University, Canada
Correspondent: Click to Email
We have investigated the tungsten-silicon contact in ultrahigh vacuum using an atomic force microscope equipped with a force-feedback force sensor. The operation of the sensor is based on balancing the tip-sample interfacial force by an electrostatic actuator. The measurements show that the force changes in discrete steps both upon approach and retraction, and the magnitude of the steps indicate that these events can be attributed to neck formation and relaxation phenomena involving only a few atoms. The data is in good agreement with previously published molecular dynamic simulations of the behaviour of sharp tips interacting with surfaces. It is shown that the commonly used calculation of the long-range van der Waals force using a spherical tip approximation is inadequate for measurements on this scale. Curves obtained using force-feedback method are compared with conventional force curves, and the role of the dynamic behaviour of the force-feedback sensor in the interpretation of force spectroscopy data will be discussed.