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Determination of Single-Bond Forces from Contact Force Variances in Atomic Force Microscopy

Atomic force microscopy contact forces are shown to obey a Poisson distribution, so that the ratio of their variance to mean gives the force of a single chemical bond between the tip and sample. The derived single-bond force was able to distinguish nominal van der Waals interactions (60 ± 3 pN) from...

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Bibliographic Details
Published in:Langmuir 1996-03, Vol.12 (5), p.1291-1295
Main Authors: Williams, John M, Han, Taejoon, Beebe, Thomas P
Format: Article
Language:English
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Summary:Atomic force microscopy contact forces are shown to obey a Poisson distribution, so that the ratio of their variance to mean gives the force of a single chemical bond between the tip and sample. The derived single-bond force was able to distinguish nominal van der Waals interactions (60 ± 3 pN) from hydrogen-bond interactions (181 ± 35 pN) between atomic force microscope tips and gold and mica surfaces, respectively. This technique greatly reduced sampling time and sample wear, allowed quantitative use of low-resolution force data from a commercially available instrument, and detected important chemical differences between surface functional groups on the samples. These experiments constitute an important step in obtaining chemically specific information in atomic force microscopy.
ISSN:0743-7463
1520-5827
DOI:10.1021/la950500j