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Chemical Force Microscopy

Published online by Cambridge University Press:  02 July 2020

Charles M. Lieber
Affiliation:
Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138
Dmitri Vezenov
Affiliation:
Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138
Aleksandr Noy
Affiliation:
Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138
Charles Sanders
Affiliation:
Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138
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Extract

Chemical force microscopy (CFM) has been used to measure adhesion and friction forces between probe tips and substrates covalently modified with self-assembled monolayers (SAMs) that terminate in distinct functional groups. Probe tips have been modified with SAMs using a procedure that involves coating commercial Si3N4 cantilever/tip assemblies with a thin layer of polycrystalline Au followed by immersion in a solution of a functionalized thiol. This methodology provides a reproducible means for endowing the probe with different chemical functional groups.

A force microscope has been used to characterize the adhesive interactions between probe tips and substrates that have been modified with SAMs which terminate with COOH and CH3 functional groups in ethanol water solvent. Force versus distance curves recorded under ethanol show that the interaction between COOH/COOH > CH3/CH3 > COOH/CH3. The measured adhesive forces were found to agree well with predictions of the Johnson, Kendall, and Roberts (JKR) theory of adhesive contact, and thus show that the observed adhesion forces correlate with the surface free energy

Type
Scanned Probe Microscopies: Technologies, Methodologies, and Applications
Copyright
Copyright © Microscopy Society of America 1997

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References

1. Frisbie, C. D. et al., Science 265(1994)2071.CrossRefGoogle Scholar

2. Noy, A. et al., J. Am. Chem. Soc. 117(1995)7943.CrossRefGoogle Scholar

3. Vezenov, D.et al, J. Am.Chem. Soc. 119(1997)2006.CrossRefGoogle Scholar

4. This work was supported by the Air Force Office of Scientific Research.Google Scholar