Mapping Orientation Differences of Terminal Functional Groups by Friction Force Microscopy

Abstract

The ability to map differences in the spatial orientation of terminal chemical groups is of major significance to areas as diverse as biological recognition and boundary lubrication. This capability is demonstrated herein using a scanning force microscope to detect differences in the friction between a probe tip and organic monolayers with different terminal group orientations. As a starting point, the basis for the discrimination of the orientation differences in terminal groups is developed through considerations of surface free energy. The viability of the concept is then confirmed by the friction imaging of samples patterned with alternating domains of organic monolayers having different terminal group orientations. Opportunities presented by this new capability are briefly noted.