Role of van der Waals forces in the adsorption and diffusion of organic molecules on an insulating surface

O. H. Pakarinen, J.M. Mativetsky, A. Gulans, M. J. Puska, A. S. Foster, P. Grutter

Research output: Contribution to journalArticleScientificpeer-review

37 Citations (Scopus)
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Abstract

The adsorption and diffusion of 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) molecules on a nanostructured KBr (001) surface were investigated by combining noncontact atomic force microscopy (NC-AFM) and first-principles calculations. Atomically resolved measurements demonstrate trapping of PTCDA molecules in intentionally created rectangular monolayer-deep substrate pits and a preferential adsorption at kink sites. In order to understand the experimental results, we found that it was essential to include a first-principles treatment of the van der Waals interactions. We show that at some sites on the surface, 85% of the molecular binding is provided by van der Waals interactions, and in general it is always the dominant contribution to the adsorption energy. It also qualitatively changes molecular diffusion on the surface. Based on the specificity of the molecular interaction at kink sites, the species of the imaged ionic sublattice in the NC-AFM measurements could be identified.
Original languageEnglish
Article number085401
Pages (from-to)1-5
Number of pages5
JournalPhysical Review B
Volume80
Issue number8
DOIs
Publication statusPublished - 2009
MoE publication typeA1 Journal article-refereed

Keywords

  • adsorption
  • atomic force microscopy
  • potassium compounds
  • surface diffusion
  • van der Waals forces,

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