The mechanism of high-resolution STM/AFM imaging with functionalized tips

Abstract

High resolution Atomic Force Microscopy (AFM) and Scanning Tunnelling Microscopy (STM) imaging with functionalized tips is well established, but a detailed understanding of the imaging mechanism is still missing. We present a numerical STM/AFM model, which takes into account the relaxation of the probe due to the tip-sample interaction. We demonstrate that the model is able to reproduce very well not only the experimental intra- and intermolecular contrasts, but also their evolution upon tip approach. At close distances, the simulations unveil a significant probe particle relaxation towards local minima of the interaction potential. This effect is responsible for the sharp sub-molecular resolution observed in AFM/STM experiments. In addition, we demonstrate that sharp apparent intermolecular bonds should not be interpreted as true hydrogen bonds, in the sense of representing areas of increased electron density. Instead they represent the ridge between two minima of the potential energy landscape due to neighbouring atoms.

Cited by in corpus (8)

• The origin of high-resolution IETS-STM images of organic molecules with functionalized tips
• Intermolecular contrast in atomic force microscopy images without intermolecular bonds
• Principles and simulations of high-resolution STM imaging with flexible tip apex
• Molecular structure elucidation with charge-state control
• Submolecular resolution by variation of IETS amplitude and its relation to AFM/STM signal
• Submolecular-resolution non-invasive imaging of interfacial water with atomic force microscopy
• Direct evidences of pentagonal silicon chains and magic clusters
• Pauli's Principle in Probe Microscopy