posted on 2012-07-11, 00:00authored byA. Siria, T. Barois, K. Vilella, S. Perisanu, A. Ayari, D. Guillot, S.T. Purcell, P. Poncharal
This article presents a study of the poorly understood
“shear-force”
used in an important class of near-field instruments that use mechanical
resonance feedback detection. In the case of a metallic probe near
a metallic surface in vacuum, we show that in the 10–60 nm
range there is no such a thing as a shear-force in the sense of the
nonconservative friction force. Fluctuations of the oscillator resonance
frequency, likely induced by local charge variations, could account
for the reported effects in the literature without introducing a dissipative
force.