Regensburg 2022 – scientific programme

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O: Fachverband Oberflächenphysik

O 29: Metal substrates 1

O 29.4: Talk

Tuesday, September 6, 2022, 11:15–11:30, S052

Quantifying the diffusion of porphyrins on Au(111): A temperature-dependant STM study — •Matthew Edmondson and Alex Saywell — School of Physics & Astronomy, University of Nottingham, Nottingham, UK

The diffusion of surface-confined molecules is a fundamental step within the formation of self-assembled structures and on-surface reactions. Scanning probe microscopies provide a route to characterising the diffusion pathways of these molecules, and allow a quantitative analysis of energetic barriers via Arrhenius-type rate analysis.(1) In particular, SPM allows the relationship between atomic-scale surface structures and molecular diffusion to be explored; a potential method for influencing on-surface reactivity.(2)

The Au(111) surface, frequently used as a substrate for on-surface coupling reactions (3), exhibits the well-known 'herringbone' reconstruction which may influence the diffusion of molecule species. In this work, we report on the diffusion of individual 2H-TPP on the Au(111) surface; characterising the diffusion rate via variable-temperature scanning tunnelling microscopy within specific regions of the reconstructed surface. The energy barrier to diffusion (obtained via Arrhenius analysis) was found to differ between the FCC and HCP regions of the herringbone reconstruction, indicating that local geometric/electronic surface-features play a role in on-surface diffusion.

1. H. Marbach, H.-P. Steinrück, Chem. Commun. 50, 9034 (2014).

2. S. Clair, D. G. de Oteyza, Chem. Rev. 119, 4717 (2019).

3. L. Grill et al., Nat. Nanotechnol. 2, 687 (2007).