| AVS 65th International Symposium & Exhibition | |
| Nanometer-scale Science and Technology Division | Friday Sessions |
| Session NS+AM+AS+MN+PC+PS+SS+TR-FrM |
| Session: | SPM – Probing Chemical Reactions at the Nanoscale |
| Presenter: | Tomasz Michnowicz, Max Planck Institute for Solid State Research, Germany, Deutschland |
| Authors: | T. Michnowicz, Max Planck Institute for Solid State Research, Germany, Deutschland B. Borca, Max Planck Institute for Solid State Research, Germany R. Pétuya, Donostia International Physics Centre, Spain M. Pristl, Max Planck Institute for Solid State Research, Germany R. Gutzler, Max Planck Institute for Solid State Research, Germany V. Schendel, Max Planck Institute for Solid State Research, Germany I. Pentegov, Max Planck Institute for Solid State Research, Germany U. Kraft, Max Planck Institute for Solid State Research, Germany H. Klauk, Max Planck Institute for Solid State Research, Germany P. Wahl, University of St Andrews, UK A. Arnau, Donostia International Physics Centre, Spain U. Schlickum, Max Planck Institute for Solid State Research, Germany K. Kern, Max Planck Institute for Solid State Research, Germany |
| Correspondent: | Click to Email |
Understanding of elementary steps and control in chemical reactions on the atomic scale might improve significantly their efficiency and applicability. Scanning tunneling microscopy (STM) allows both investigating and stimulating chemical reactions of individual organic subunits, for example via the tunneling current, electric field or a mechanical interaction. Here we present a study of an STM stimulated desulfurization process of the thiophene functional group embedded in a tetracenothiophene (TCT) molecule on a Cu(111) surface. Precise positioning and applying stimuli with the STM tip apex allows determination of a two-step process responsible for this chemical reaction. High resolution STM images, supported by the DFT calculations, help us to correlate the first reaction step to the breaking of one the carbon-sulfur bonds and the second to the breaking of the second carbon-sulfur bond. The latter reaction also results in a significant increase of the bond strength of the broken thiophene part to Cu surface atoms. The chemical reaction is triggered by positioning the tip apex above the thiophene part and applying a threshold voltage that depends linearly on the tip-molecule distance. This linear dependence is a hallmark of an electric field driven process. In addition, conduction measurements through single TCT molecules before and after the reaction have been performed. Compared to the intact molecule we observed a 50% increase of conductance after the chemical reaction, which is in agreement with the finding of a much stronger bond formation between the molecule and Cu surface atoms.