Berlin 2008 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 51: Metal Substrates: Adsorption of Organic/Bio Molecules III
O 51.6: Vortrag
Mittwoch, 27. Februar 2008, 16:30–16:45, MA 041
Molecular self-assembly on an ultrathin insulating film — •Christian Bombis1,2, Nataliya Kalashnik1, Wei Xu1, Erik Laegsgaard1, Flemming Besenbacher1, and Trolle Linderoth1 — 1Department of Physics and Astronomy, and iNANO, University of Aarhus, 8000 Aarhus C, Denmark — 2Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
Molecular self-assembly of cyanuric acid (CA) and melamine (M) on an ultrathin NaCl film grown on Au(111) is investigated by means of STM. Since it was shown that an ultrathin insulating film of NaCl on a metallic substrate enables electronical decoupling of an adsorbed molecule from the conducting substrate, while still allowing imaging of the molecule with STM, this method gained increasing attention for reasons of practical interest. However, due to weak molecule-substrate interactions stabilization of the molecules on alkali halides is a challenging task. In the present study we present the preparation and growth of ultrathin NaCl films in submonolayer quantities on Au(111). CA and M were thermally evaporated on such a NaCl/Au(111) substrate held at room temperature. We were able to image ordered molecular islands at comparatively high temperatures between 120 and 180 K on top of the NaCl film, which are nucleated at NaCl step edges. As we could identify the same adsorption structures on the NaCl film as previously reported by Xu et al.* for CA and M on pure Au(111), we conclude that the stabilization of the molecules is facilitated by their ability to form complementary triple hydrogen bond motifs with a high intermolecular interaction strength. *small 2007, 3, No. 5, 854-858