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

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© 2009 American Physical Society (APS). This is the accepted version of the following article: Pakarinen, O. H. ; Mativetsky, J. M. ; Gulans, A. ; Puska, M. J. ; Foster, Adam S. ; Grutter, P.. 2009. Role of van der Waals forces in the adsorption and diffusion of organic molecules on an insulating surface. Physical Review B. Volume 80, Issue 8. 085401/1-5. ISSN 1550-235X (electronic). DOI: 10.1103/physrevb.80.085401, which has been published in final form at http://journals.aps.org/prb/pdf/10.1103/PhysRevB.80.085401.

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Journal Title

Journal ISSN

Volume Title

School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

Date

2009

Major/Subject

Mcode

Degree programme

Language

en

Pages

085401/1-5

Series

Physical Review B, Volume 80, Issue 8

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.

Description

Keywords

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

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Citation

Pakarinen, O. H. & Mativetsky, J. M. & Gulans, A. & Puska, M. J. & Foster, Adam S. & Grutter, P.. 2009. Role of van der Waals forces in the adsorption and diffusion of organic molecules on an insulating surface. Physical Review B. Volume 80, Issue 8. 085401/1-5. ISSN 1550-235X (electronic). DOI: 10.1103/physrevb.80.085401.