Berlin 2008 – scientific programme

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O: Fachverband Oberflächenphysik

O 30: Phenomena at Semiconductor Surfaces

O 30.4: Talk

Tuesday, February 26, 2008, 12:45–13:00, MA 041

Terephthalic acid (TPA) on Si(111)-7×7 and Si(111)-( 3)^1/×( 3)^1/-Ag surfaces — •Takayuki Suzuki, Theresa Lutz, Giovanni Costantini, and Klaus Kern — Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, D-70569 Stuttgart

We have carried out STM measurements of terephthalic acid (TPA) deposited on Si(111)7×7 and Si(111)-( 3)^1/×( 3)^1/-Ag surfaces. Due to a strong molecule-substrate interaction, TPA molecules do not form any ordered molecular layer but adsorb randomly on the Si(111)7×7 surface with several binding motifs. On the contrary, the interaction of TPA with the Si(111)-( 3)^1/×( 3)^1/-Ag surface is much weaker allowing for the formation of an ordered layer stabilized by intermolecular hydrogen bonds. The TPA overlayer is characterized by a modulation of about 2nm in period along the ⟨112⟩ direction. This periodicity is not uniform but appears wider in some places and narrower in the others. The wide and the narrow regions have a parallelogram 30
−2 7 and a rectangular 30
−3 6 unit cell comprising 5 and 4 TPA molecules, respectively. This study demonstrates the viability of silver passivated silicon surfaces as optimal substrates for supramolecular self-organisation.