Strumming a Single Chemical Bond
Alfred J. Weymouth, Elisabeth Riegel, Oliver Gretz, Franz J. Gießibl
Abstract
Atomic force microscopy and scanning tunneling microscopy can image the internal structure of molecules adsorbed on surfaces. One reliable method is to terminate the tip with a nonreactive adsorbate, often a single CO molecule, and to collect data at a close distance where Pauli repulsion plays a strong role. Lateral force microscopy, in which the tip oscillates laterally, probes similar interactions but has the unique ability to pull the CO over a chemical bond, load it as a torsional spring, and release it as it snaps over with each oscillation cycle. This produces measurable energy dissipation. The dissipation has a characteristic decay length in the vertical direction of 4 pm, which is 13 times smaller than the decay length in typical STM or AFM experiments.