Bond-order discrimination by atomic force microscopy

Science. 2012 Sep 14;337(6100):1326-9. doi: 10.1126/science.1225621.

Abstract

We show that the different bond orders of individual carbon-carbon bonds in polycyclic aromatic hydrocarbons and fullerenes can be distinguished by noncontact atomic force microscopy (AFM) with a carbon monoxide (CO)-functionalized tip. We found two different contrast mechanisms, which were corroborated by density functional theory calculations: The greater electron density in bonds of higher bond order led to a stronger Pauli repulsion, which enhanced the brightness of these bonds in high-resolution AFM images. The apparent bond length in the AFM images decreased with increasing bond order because of tilting of the CO molecule at the tip apex.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carbon Monoxide / chemistry*
  • Copper / chemistry
  • Electrons
  • Microscopy, Atomic Force
  • Molecular Structure
  • Polycyclic Aromatic Hydrocarbons / chemistry*
  • Polycyclic Compounds / chemistry
  • Sodium Chloride / chemistry

Substances

  • Polycyclic Aromatic Hydrocarbons
  • Polycyclic Compounds
  • Sodium Chloride
  • Copper
  • Carbon Monoxide
  • coronene