Jens Brede et al 2009 Nanotechnology 20 275602 doi:10.1088/0957-4484/20/27/275602
Jens Brede1, Mathieu Linares2,3, Stefan Kuck1, Jörg Schwöbel1, Alessandro Scarfato1,4, Shih-Hsin Chang1, Germar Hoffmann1, Roland Wiesendanger1, Roy Lensen5, Paul H J Kouwer5, Johan Hoogboom5, Alan E Rowan5, Martin Bröring6, Markus Funk6, Sven Stafström2, Francesco Zerbetto7 and Roberto Lazzaroni3
Show affiliationsA 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 π–π 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.
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)
Issue 27 (8 July 2009)
Received 26 February 2009, in final form 25 April 2009
Published 17 June 2009
Jens Brede et al 2009 Nanotechnology 20 275602
Ji-Yong Park 2007 Nanotechnology 18 095202
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