Formation of a One-Atom Contact on Pb: Adhesion and Energy Dissipation

Quartz Tuning Fork (TF) has been recently successfully implemented in force detection schemes for scanning probe microscopy applications [1]. Here we report its use as a nanotribometer for studying energy dissipation and the forces in the formation of a single atom contact. The idea behind such a noncontact mono-atomic energy dissipation detector, is to take advantage of the mechanical resonance of a TF which has a large Q-factor (Q_4.2K∼150000) which in our set-up is a function of the tip-sample dissipative forces. Finally, we report measurements of the shift in the resonance frequency and the Q-factor degradation of the oscillating TF, either as a function of the tip-sample voltage or distance. These experiments have been done on Pb close to the superconducting transition temperature in high vacuum. [4pt] [1] S. Morita, et. al. Noncontact Atomic Force Microscopy, Nanoscience and Technology (Springer-Verlag, Berlin 2002)