Functional Group Imaging by Chemical Force Microscopy

Science  30 Sep 1994:
Vol. 265, Issue 5181, pp. 2071-2074
DOI: 10.1126/science.265.5181.2071


Mapping the spatial arrangement of chemical functional groups and their interactions is of significant importance to problems ranging from lubrication and adhesion to recognition in biological systems. A force microscope has been used to measure the adhesive and friction forces between molecularly modified probe tips and organic monolayers terminating in a lithographically defined pattern of distinct functional groups. The adhesive interactions between simple CH3/CH3, CH3/COOH, and COOH/COOH functional groups correlate directly with friction images of sample surfaces patterned with these groups. Thus, by monitoring the friction between a specifically functionalized tip and sample, one can produce friction images that display predictable contrast and correspond to the spatial distribution of functional groups on the sample surface. Applications of this chemically sensitive imaging technique are discussed.