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Influencing the conductance in biphenyl-like molecular junctions with THz radiation

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Abstract

We investigate the torsional vibrations in biphenyl-like molecular junctions and transport properties in the presence of an external THz field. Ab initio calculations including external electric fields show that the torsional angle math formula of a thiolated biphenyl junction exhibits virtually no response. However, if functional groups are added to the molecule, creating a dipole moment in each of the rings, an external field becomes more effective for changing math formula. A model based on the math formula dependence of the current for low bias voltages has been proposed for the biphenyl-like molecular junctions in presence of an external THz field including 2,2math formula-bipyridine, 3,3math formula-bipyridine, and 2,2math formula,4,4math formula-tetramethyl-3,3math formula-bipyridine. The current through these molecules is shown to change if the THz frequency gets in resonance to the torsional vibration mode.

pssb201349221-gra-0001

Dithiolated bipyridine between gold leads in the presence of external THz radiation.

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