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DS: Dünne Schichten
DS 25: Spezielle Schichten III
DS 25.3: Talk
Thursday, March 29, 2001, 16:45–17:00, S 13/14
Structure and electronic properties of mixed PTCDA-alkanethiols systems on Au(111) — •Jens Pflaum1,2, Giacinto Scoles3,2, and Antoine Kahn1,2 — 1Dept. Electrical Engineering, Princeton Univ., Princeton, NJ 08544, USA — 2Princeton Materials Institute, Princeton Univ., Princeton, NJ 08544, USA — 3Dept. Chemistry, Princeton Univ., Princeton, NJ 08544, USA
This study demonstrates that the structural arrangement of mixed organic systems consisting of PTCDA and alkanethiols can be engineered by the route of preparation. In a first series of experiments, a submonolayer of PTCDA is deposited on the low density lying down phase of decanethiols on Au(111). Scanning Tunneling Microscopy (STM) shows that the PTCDA molecules displace the underlying thiols and form islands of a square lattice different from that of the square phase found for PTCDA on bare Au(111). Increasing the PTCDA coverage results in lateral expansion of the PTCDA islands and in reduction of the areas covered by thiols. The latter are forced into standing up formations of higher density. In a second experiment, PTCDA is deposited on the standing up phase of decanethiols and annealed at 373K. In this case it is shown by STM that the PTCDA molecules form islands of the herringbone phase comparable to that observed for PTCDA on bare Au(111). The impact of the different structural configurations on the electronic properties of the molecular components, measured via scanning tunneling spectroscopy, is discussed. Work is supported by the Deutsche Forschungsgemeinschaft (Grant No. PF 385/1-1) and by the MRSEC program of the NSF (DMR 98-09483).