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O: Oberflächenphysik

O 29: Poster session II (Nanostructures, Magnetism, Particles and clusters, Scanning probe techniques, Time-resolved spectroscopy, Structure and dynamics, Semiconductor surfaces and interfaces, Oxides and insulators, Solid-liquid interfaces)

O 29.79: Poster

Wednesday, March 29, 2006, 14:30–17:30, P2

The structure of ordered iodine layers on Pt(100) in electrolyte and air — •Björn Braunschweig and Winfried Daum — Institut für Physik und Physikalische Technologien, TU Clausthal, Leibnizstrasse 4, D-38678 Clausthal-Zellerfeld

Well-defined iodine adlayers, prepared by flame annealing and subsequently quenching in iodine vapor, were studied by scanning tunneling microscopy (STM) in air and a 0.1M HClO₄ electrolyte with atomic-resolution. The I-Pt(100) surface showed atomically flat terraces with monoatomic steps mainly along the [010] direction. At low iodine coverage STM in air reveals domains of clean reconstructed Pt(100)-hex and domains of an ordered (√2× 5√2)R45^∘-I adlattice on Pt(100)-(1x1). At high coverage iodine formes a complete (√2× 5√2)R45^∘ layer on the Pt(100) surface which consists of a defect-free phase with iodine rows perpendicular to the main direction of the terrace steps, and a defect-rich phase with iodine rows parallel to the steps and with quasi-one-dimensional defects along the [010] direction. The boundary between the two phases is found to be atomically abrupt. Contrary to our STM data in 0.1M HClO₄ which are in agreement with previous work [1], STM imaging in air reveals buckled iodine double-rows. The strength of buckling depends on tunneling resistance and on the orientation of the (√2× 5√2)R45^∘ domains.

[1] R. Vogel and H. Baltruschat; Surf. Sci. Lett. 259,L739-42(1991)