Berlin 2015 – scientific programme

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O: Fachverband Oberflächenphysik

O 65: Oxides and Insulators

O 65.3: Poster

Wednesday, March 18, 2015, 18:15–21:00, Poster A

adsorption of PTCDA on KCl and NaCl(100) surfaces — Hazem ALdahhak, •Wolf Gero Schmidt, and Eva Rauls — Universität Paderborn, Warburger Str. 100, 33098 Paderborn

The adsorption of PTCDA (C24H8O6) on metal substrates has for a long time been used as model system for understanding molecular self-assembly. Ionic crystals as substrate provide the additional possibility to study the molecular properties with little perturbation by substrate screening or strong substrate-adsorbate bonds [1]. Here, we present density-functional theory calculations on the adsorption and adsorbate-substrate interaction between PTCDA and planar and as well as stepped NaCl as well as KCl surfaces. The adsorption is dominated by van-der-Waals and electrostatic forces. This lead to a site-specific adsorption of the molecule on the surface, possibly resulting in commensurate long-range ordered structures [2]. The influence of the substrate and bonding mechanism on the molecular electronic structure as well as the molecular vibrations is investigated in detail and compared with the experimental data available [3-5]. Our calculations for different kinds of step-edge defects show the importance of these surface defects for initiating the adsorption of organic molecules on ionic surfaces.

[1] V. W. Henrich, P.A Cox, The surface of metal Oxides, vol.1, Cambridge University Press, 1996 [2] H. Aldahhak et al, Surf. Sci. 617, 242-248, 2013. [3] Que et al., J. Phys. Chem. C (in Press). [4] H Karacuban et al. Nanotechnology, 22 (29), 295305, 2011. [5] A. Paulheim et al., Phys. Chem. Chem. Phys.15 (2013) 4906.