Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 35: Poster Session II (Polymeric biomolecular films; Nanostructures; Electronic structure; Spin-orbit interaction; Phase transitions; Surface chemical reactions; Heterogeneous catalysis; Particles and clusters; Surface magnetism; Electron and spin dynamics; Surface dynamics; Methods; Electronic structure theory; Functional molecules)
O 35.108: Poster
Dienstag, 27. März 2012, 18:15–21:45, Poster B
Electron induced dynamics of hepthathioether β-cyclodextrin molecules — •Avijit Kumar1, René Heimbuch1, Kim S. Wimbush2, Hasan Atesci1, Adil Acun1, David N. Reinhoudt2, Aldrik H. Velders2,3, and Harold J W Zandvliet1 — 1Physics of Interfaces and Nanomaterials, MESA+ Institute for Nanotechnology — 2Supramolecular Chemistry and Technology, MESA+ Institute for Nanotechnology — 3Biomolecular Chemistry, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, the Netherlands
Macroscopic junctions using Self Assembled Monolayers (SAMs) are prevalent in charge transport studies in molecular electronics. However, the macroscopic nature of metal-molecules contacts lead to an ensemble averaging of the transport events that occur across array of contacted molecules. Here, we have performed variable temperature scanning tunneling microscopy (STM) and spectroscopy (STS) measurements on hepthathioether β-cyclodextrin (β-CD) SAMs on Au to investigate dynamical behavior, which is not apparent in ensemble averaged studies. The dynamics is reflected in the tunneling current-time (I-t) traces, which were recorded with the STM feedback disabled. The dynamics is temperature independent, but increases with increasing tunneling current and sample bias, indicating that the conformational changes of the β-CD molecules are induced by electrons that tunnel inelastically. Even for sample biases as low as 10 mV we observe well-defined levels in the I-t traces. We attribute these jumps to the excitations of the molecular vibration of the macrocyclic β-CD molecule.