Noncontact Atomic Force Microscopy - Yale School of Engineering ...

Influence of thermal noise on measurements of
chemical bonds in UHV-AFM
Peter M. Hoffmann
Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201
P.I-07
Ultra-high vacuum based AFM has been repeatedly shown to provide high resolution
measurements of forces and force gradients associated with chemical bonds 1-5 . However,
the bond parameters, such as bond length and energies, have varied between
measurements. One theory put forward for these discrepancies has been the influence of
thermal noise on measurements performed at room temperature. In FM-AFM it was
originally found that bond force curves seem broadened when measured at room
temperature 1 , and theoretically expected bond lengths were only recovered when
measurements were obtained at low temperature 2 . On the other hand, AM-AFM
performed at small amplitudes found no such broadening at room temperature 3 . More
recent measurements using FM AFM at room temperature, however, also seem to show
shorter interaction lengths 4,5 . What, if any, is the influence of cantilever thermal noise on
measured interaction lengths? We present a simulation study of the influence of thermal
noise on measurements of interaction forces using FM or AM AFM.
[1] M. Guggisberg, et al., Phys. Rev. B 61, 11151 (2000).
[2] M. A. Lantz, et al., Science 291, 2580 (2001).
[3] P.M. Hoffmann, et al.. Proc. Royal Soc. Lond. 457, 1161-1174 (2001).
[4] Y. Sugimoto et al., Phys. Rev. B 77, 195424 (2008).
[5] K. Ruschmeier et al., Phys. Rev. Lett. 101, 156102 (2008)
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