Berlin 2012 – scientific programme
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O: Fachverband Oberflächenphysik
O 6: Scanning probe methods I
O 6.10: Talk
Monday, March 26, 2012, 12:45–13:00, MA 043
Atomic Forces and Energy Dissipation of a Bi-Stable Molecular Junction — •Christian Lotze1, Martina Corso1, Katharina Franke1, Felix von Oppen2, and Nacho Pascual1 — 1Inst. f. Experimentalphysik FU Berlin — 2Inst. f. theoretische Physik FU Berlin
Tuning Fork based dynamic STM/AFM is a well established method combining the advantages of scanning tunneling and dynamic force microscopy. Using tuning forks with high stiffness, stable measurements with small amplitudes, below 1 Å can be performed. In this way, conductance and frequency shift measurements of molecular junction can be obtained simultaneously [1] with intramolecular resolution [2].
One of the most intriguing aspects of molecular junctions relates to the effect of structural bi-stabilities to the properties of the junction. These lead, for example, to conductance fluctuations, telegraph noise and the possibility to switch the electrical transport through the junction.
In this presentation, we characterize a model bi-stable molecular system using dynamic force spectroscopy. The effect of current-induced stochastic fluctuations of conductance are correlated with fluctuations in force. In our experiment we identified the last from both, frequency shifts and energy dissipation measurements, picturing a regime in which electrical transport and mechanical motion are coupled.
[1] N. Fournier et. al, PhysRevB 84, 035435 (2011),
[2] L. Gross et. al, Science 324, 1428 (2009)