Quantifying Molecular Stiffness and Interaction with Lateral Force Microscopy

Abstract

A Soft Molecular Spring In noncontact atomic force microscopy, extremely high resolution has been achieved by attaching a terminal CO molecule to the metal scanning probe tip. This CO molecule can undergo torsional vibrations, and a full understanding of the imaging mechanism requires a measure of this spring constant. Weymouth et al. (p. 1120 , published online 6 February; see the Perspective by Salmeron ) used lateral force microscopy, in which the tip vibrates laterally across the surface, to determine this torsional constant. The stiffness of the isolated CO molecules on the tip was much less than that for CO molecules adsorbed on planar surfaces.