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O: Oberflächenphysik

O 36: Postersitzung (Elektronische Struktur, Grenzfl
äche fest-flüssig, Halbleiteroberfl
ächen und -grenzfl
ächen, Nanostrukturen, Oberfl
ächenreaktionen, Teilchen und Cluster, Struktur und Dynamik reiner Oberfl
ächen)

O 36.23: Poster

Montag, 7. März 2005, 15:00–18:00, Poster TU F

Structural changes of a TMPyP layer on a Cu(100)/Cl - Surface within the corrosion region — •Minh Hai Nguyen Thi, Blazenka Gasparovic, Peter Broekmann, and Klaus Wandelt — Institut für Physikalische und Theoretische Chemie, Universität Bonn, Wegelerstr. 12, 53115 Bonn

The self-assembly of 5,10,15,20-Tetrakis-(N-methyl-4-pyridyl)-21H,23H-porphyrin tetrachloride (TMPyP) on an Chloride-Modified Cu(100) electrode within the copper corrosion regime was investigated by using Electrochemical Scanning Tunneling Microscopy (EC-STM). A highly ordered TMPyP adlayer was observed at a potential of E = - 400 mV vs.Ag/AgCl which became disordered when the applied potential was changed more positive into the regime of copper corrosion. This process is reversible, that the highly ordered porphyrin layer is restored when the potential is turned back into the negative direction. The corrosion process was found to be favoured at step-edges and to run along the close-packed chloride rows like in the case of the corrosion of Cu(100) in the pure chloride containing electrolyte. High resolution EC-STM images indicated that the structure of TMPyP on the Cu(100)/Cl surface is (3√2 × 3√2) R45^∘ with respect to the chloride (2 × 2) layer or (6 × 6) with respect to the Cu(100).