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O: Fachverband Oberflächenphysik

O 91: Nanostructures at Surfaces: Molecular Systems I

O 91.3: Vortrag

Donnerstag, 23. März 2017, 11:00–11:15, REC/PHY C213

Charge switching in multi-ferrocene molecules observed — •Martin Ondráček, Pavel Jelínek, Jan Berger, Oleksandr Stetsovych, and Martin Švec — Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic

The ability to switch between different redox states makes ferrocene molecules an attractive subject of research aiming to nano-scale electronics. Linking several ferrocene units into multi-ferrocene molecules expands the potential functionality, due to the interaction among the individual ferrocene sub-units and the possibility to switch their charge state in a coordinated manner. Our study shows how the charge of bis- and tetra-ferrocene molecules on NaCl substrate can be detected and controlled by an atomic force microscope (AFM). Here, I focus on theoretical explanation of the main features observed in the AFM and electrostatic force spectroscopy (EFM) with these molecules. Especially notable are sharp boundary-like features characterized by increased frequency shift as well as an increased energy dissipation signal. We interpret them in terms of charge transfer among the ferrocene centers facilitated by the AFM tip. Using a modified version of an earlier written simulator [1], we back our interpretation with a model that encompasses the AFM cantilever dynamics and electrons hopping among the AFM tip and ferrocene centers. We supplement our empirical model with DFT-based calculations of the geometry and electronic structure of the molecules on NaCl.

[1] M. Ondráček, P. Hapala, P. Jelínek, Nanotechnology 27, 274005 (2016).