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Lecture Diana Dulic


25 October 2011 FWN-Building 5118.-152, Nijenborgh 4, 9747 AG, Groningen
Speaker: Dr. Diana Dulic
Affiliation: Kavli Institute of Nanoscience, Delft University of Technology
Title: Mechanically tunable current - voltage spectroscopy of molecular levels in single-molecule junctions
Date: Tue Oct 25, 2011
Start: 14.00
Location: FWN-Building 5118.-152
Host: Paul van Loosdrecht
Telephone: +31 50 363 8149


We investigated the nature of charge transport through electrostatically gated single-molecule devices with tuneable source-drain geometry at cryogenic temperatures. Varying the inter-electrode distance allows us to probe different charge transport regimes and to monitor molecular level shifts with respect to the Fermi energy of the metal contacts Those shifts are a result of the interplay between the molecule's electronic structure and interface effects. The electrostatic gate allows us to probe which levels participate in the charge transport and determine their dependence on the electrode spacing.  I will present and compare our results on non-rod-like porphyrin molecules to a series of rod-like anthracene derivatives. The experimental findings combined with DFT-based transport calculations show that the observed gap renormalization is dominated by the image-charge effect. By tuning the electrode spacing for the anthracene derivatives, we are able to access various transport regimes, which exhibit rich IV spectra. Using a tight-binding model approach, we can qualitatively understand some of the observed spectroscopic features. Our approach is indispensable for full understanding of the charge transport on a single – molecule level and the fundamental mechanisms that determine the processes at the interfaces of metals and conjugated molecules.

Last modified:22 October 2012 2.31 p.m.