Berlin 2012 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 44: Focussed session: Functional molecules at surfaces II

O 44.3: Vortrag

Mittwoch, 28. März 2012, 11:30–11:45, A 053

Direct observation of molecular switching at and close to room temperature by scanning tunneling microscopy — •Stefanie Ditze, Florian Buchner, Michael Stark, Hans-Peter Steinrück, and Hubertus Marbach — Lehrstuhl für Physikalische Chemie II and Interdisciplinary Center for Molecular Materials (ICMM), Universität Erlangen-Nürnberg, Egerlandstr. 3, D-91058

An ultimate goal of nanotechnology is the usage of individual molecules as functional entities. One important example is the application of switchable molecular building blocks in information storage. Herein, we report the observation of a supramolecular ordered phase of 2H-5,10,15,20-Tetrakis(3,5-di-tert-butyl)-phenylporphyrin (2HTTBPP) on Cu(111) by scanning tunneling microscopy (STM) in ultra-high vacuum around room temperature (RT). In this phase, the 2HTTBPP molecules are arranged in alternating rows with intrinsically different intramolecular conformations, i.e. a concave and a convex appearance in STM. Interestingly, it was found that individual 2HTTBPP molecules spontaneously switch between these two conformations at RT. Detailed analysis of the temperature dependence of the switching behavior allows to extract the activation energies and the prefactors for the molecular switching process. In addition, we demonstrate tip-induced switching of individual molecules at 200 K.

This work has been funded by the Deutsche Forschungsgemeinschaft (DFG) through Sonderforschungsbereich 583.