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

• Published in: Langmuir Vol. 12; no. 5; pp. 1291 - 1295
• Main Authors: Williams, John M, Han, Taejoon, Beebe, Thomas P
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 06.03.1996
• Subjects: Atomic force microscopes; Exact sciences and technology; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Physics; Scanning probe microscopes, components and techniques; Van der Waals binding; Atomic force microscopy; Gold; Hydrogen bonds; Scanning probe microscopy; Chemical bonds; Mechanical contacts; Experimental study; Mica
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/la950500j

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.