Dresden 2020 – scientific programme
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O: Fachverband Oberflächenphysik
O 64: Organic Molecules on Inorganic Substrates IV: Adsorption, Growth and Networks
O 64.3: Talk
Wednesday, March 18, 2020, 11:00–11:15, TRE Phy
Quantitative confirmation of the inverted adsorption structure for 2H-tetraphenyl porphyrin on Cu(111) — Paul T. P. Ryan1,2, Paula L. Lalaguna1,3, Felix Haag4, Mona M. Braim5, Pencheng Ding5,6, David J. Payne2, Johannes V. Barth4, Tien-Lin Lee1, D. Phil Woodruff5, Francesco Allegretti4, and •David A. Duncan1 — 1Diamond Light Source, Didcot, UK — 2Imperial College London, UK — 3University of Glasgow, UK — 4Technical University of Munich, Germany — 5University of Warwick, Coventry, UK — 6Harbin Institute of Technology, China
The inverted model has been proposed as the adsorption structure for tetraphenyl porphyrin (2H-TPP) on Cu(111) in recent publications[1,2]. In this model two of the 2H-TPP pyrrole rings are tilted almost perpendicular to the surface, moving the iminic N atoms into a surface bridge site and breaking the aromaticity of the porphyrin macrocycle. Published X-ray standing waves (XSW) data [3] was used to justify this model, yet that study was dogged by radiation damage and did not probe the lateral adsorption site of the molecule. Here we present a XSW study without such damage, addressing the lateral adsorption site of the iminic N atoms. These atoms are indeed found to occupy bridge or near-bridge adsorption sites on the surface, displaced laterally by 1.1±0.2Åfrom direct atop sites. This result is in excellent agreement with the predicted value for these parameters in the inverted model, from the DFT calculations of Lepper et al., of 1.18 Å. [1] Chem. Comm. 53, 8207 (2017); [2] Chem. Mater. 31, 3009 (2019); [3] J. Phys. Chem. C 118, 13659 (2014)