Berlin 2012 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 44: Transport: Nanoelectronics III - Molecular Electronics 2
TT 44.4: Talk
Thursday, March 29, 2012, 15:45–16:00, BH 334
THz torsional vibrations in biphenyl-based molecular junctions: transient oscillations and resonance — •Matthias Hinreiner1, Dmitry Ryndyk1, Denis Usvyat2, Thomas Merz2, Martin Schütz2, and Klaus Richter1 — 1Institute for Theoretical Physics, University of Regensburg, Regensburg, Germany — 2Institute for Physical and Theoretical Chemistry, University of Regensburg, Regensburg, Germany
We investigate the torsional vibrations in biphenyl-based molecular junctions and transport properties in presence of an external THz field.
Ab-initio calculations with external electric fields show that the torsional angle φ of 4,4’-dithiol-biphenyl demonstrates only very tiny response. However, if functional groups are added to the molecule to induce a dipole moment in each of the rings, an external field can change φ. Two examples of such molecules are 3,3’-diflouride-4,4’-dithiol-biphenyl and 2,2’-dithiol-5,5’-bipyridine. As the conductivity of biphenyl-based molecules is proportional to cos2(φ), we show that the current through these molecules drops if the external THz field frequency gets in resonance to the torsional vibration mode.