Regensburg 2016 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 5: Dynamics of Molecules on Surfaces

O 5.6: Vortrag

Montag, 7. März 2016, 11:45–12:00, S053

Force-induced tautomerization in a single molecule — •Janina N. Ladenthin¹, Thomas Frederiksen^{2, 3}, Mats Persson⁴, Sylwester Gawinkowski⁵, Jacek Waluk⁵, and Takashi Kumagai¹ — ¹Department of Physical Chemistry, Fritz-Haber Institute of the Max-Planck Society, Berlin, Germany. — ²Donostia International Physics Center, San Sebastián, Spain. — ³IKERBASQUE, Basque Foundation for Science, Bilbao, Spain. — ⁴Surface Science Research Centre and Department of Chemistry, University of Liverpool, UK. — ⁵Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland.

Chemical reactions can be activated by heat, electric or light energy. Force is another way but the fundamental process of mechanical activation is much less studied. Force-induced bond breaking and formation are the elementary steps in mechanochemical reactions. However, it remains poorly understood at the single-molecule level. In the talk, we present the force-induced intramolecular H-atom transfer (tautomerization) in a single porphycene molecule on the Cu(110) surface at 5 K using nc-AFM. Porphycene is an intriguing model system for studies of tautomerization [1]. Force spectroscopy was employed to quantify the force needed to trigger the cis-cis tautomerization, revealing a few hundred pN. It was also found that the tautomerization cannot be induced with a Xe-terminated tip, indicating the importance of chemical forces. Furthermore, DFT calculations elucidated the atomistic mechanism behind the force-induced tautomerization.

[1] T. Kumagai et al. PRL 111, 246101 (2013); T. Kumagai et al. Nature Chem. 6, 41 (2014); T. Kumagai, Prog. Surf. Sci. 90, 239 (2015).