Intermolecular Contrast in Atomic Force Microscopy Images without Intermolecular Bonds

ROM 2015-05
Author: Ingmar Swart,
Institute: Debeye Institute for Nanomaterials Science, Netherlands
Instrument: LT STM, Low Temperature SPM

By using molecule modified AFM tips, the chemical structure of molecules can be visualized. Recently, also intermolecular contrast has been observed. These features in atomic force microscopy images of organic molecules have been ascribed to intermolecular bonds. A recent theoretical study [P. Hapala et al., Phys. Rev. B 90, 085421 (2014)] showed that intermolecular contrast can also be explained by the flexibility of molecule-terminated tips. We probed this effect by carrying out atomic force microscopy experiments on a model system that contains regions where intermolecular bonds should and should not exist between close-by molecules. Intermolecular features are observed in both regions, demonstrating that intermolecular contrast cannot be directly interpreted as intermolecular bonds.

Authors: Sampsa K. Hämäläinen1, Nadine van der Heijden2, Joost van der Lit2, Stephan den Hartog2, Peter Liljeroth1, and Ingmar Swart2

Institutes: 1 Department of Applied Physics, Aalto University School of Science, PO Box 15100, 00076 Aalto, Finland
2 Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, PO Box 80000, 3508 TA Utrecht, the Netherlands