AVS 59th Annual International Symposium and Exhibition
    Scanning Probe Microscopy Focus Topic Wednesday Sessions
       Session SP+AS+BI+ET+MI+NM+NS+SS+TF-WeM

Paper SP+AS+BI+ET+MI+NM+NS+SS+TF-WeM4
Atomic Forces and Energy Dissipation of a Bi-Stable Molecular Junction

Wednesday, October 31, 2012, 9:00 am, Room 16

Session: Probe-Sample Interactions, Nano-Manipulation and Fabrication
Presenter: C. Lotze, Freie Universtiät Berlin, Germany
Authors: C. Lotze, Freie Universtiät Berlin, Germany
M. Corso, Freie Universität Berlin, Germany
K.J. Franke, Freie Universität Berlin, Germany
F.V. Oppen, Freie Universität Berlin, Germany
J.I. Pascual, Freie Universität Berlin, Germany
Correspondent: Click to Email

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)