title: Dynamics of molecular self-ordering in tetraphenyl porphyrin monolayers on metallic substrates.
abstract: A molecular model system of tetraphenyl porphyrins (TPP) adsorbed on metallic substrates is systematically investigated within a joint scanning tunnelling microscopy/molecular modelling approach. The molecular conformation of TPP molecules, their adsorption on a gold surface and the growth of highly ordered TPP islands are modelled with a combination of density functional theory and dynamic force field methods. The results indicate a subtle interplay between different contributions. The molecule-substrate interaction causes a bending of the porphyrin core which also determines the relative orientations of phenyl legs attached to the core. A major consequence of this is a characteristic (and energetically most favourable) arrangement of molecules within self-assembled molecular clusters; the phenyl legs of adjacent molecules are not aligned parallel to each other (often denoted as pi-pi stacking) but perpendicularly in a T-shaped arrangement. The results of the simulations are fully consistent with the scanning tunnelling microscopy observations, in terms of the symmetries of individual molecules, orientation and relative alignment of molecules in the self-assembled clusters.
authors.affiliation: Institute of Applied Physics, University of Hamburg, Jungiusstrasse 9, 20355 Hamburg, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Brede
authors.forename: Mathieu
authors.initials: M
authors.lastname: Linares
authors.forename: Stefan
authors.initials: S
authors.lastname: Kuck
authors.forename: Jörg
authors.initials: J
authors.lastname: Schwöbel
authors.forename: Alessandro
authors.initials: A
authors.lastname: Scarfato
authors.forename: Shih-Hsin
authors.initials: SH
authors.lastname: Chang
authors.forename: Germar
authors.initials: G
authors.lastname: Hoffmann
authors.forename: Roland
authors.initials: R
authors.lastname: Wiesendanger
authors.forename: Roy
authors.initials: R
authors.lastname: Lensen
authors.forename: Paul H J
authors.initials: PH
authors.lastname: Kouwer
authors.forename: Johan
authors.initials: J
authors.lastname: Hoogboom
authors.forename: Alan E
authors.initials: AE
authors.lastname: Rowan
authors.forename: Martin
authors.initials: M
authors.lastname: Bröring
authors.forename: Markus
authors.initials: M
authors.lastname: Funk
authors.forename: Sven
authors.initials: S
authors.lastname: Stafström
authors.forename: Francesco
authors.initials: F
authors.lastname: Zerbetto
authors.forename: Roberto
authors.initials: R
authors.lastname: Lazzaroni
mesh_terms: D000327:Adsorption; D003035:Cobalt / Q000737:chemistry; D003198:Computer Simulation; D003300:Copper / Q000737:chemistry*; D005740:Gases / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D007700:Kinetics; D016252:Microscopy, Scanning Tunneling; D008958:Models, Molecular; D008968:Molecular Conformation; D036103:Nanotechnology / Q000379:methods; D011166:Porphyrins / Q000737:chemistry*; D013499:Surface Properties; D013816:Thermodynamics
chemical_list: D005740:Gases; D011166:Porphyrins; C409084:tetraphenylporphyrin; D003035:Cobalt; D006046:Gold; D003300:Copper