Dresden 2009 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 52: Metal substrates: Adsorption of organic / bio molecules VII

O 52.17: Vortrag

Donnerstag, 26. März 2009, 19:00–19:15, SCH A118

STM observations of the interaction of NO and CO with adsorbed metalloporphyrin molecules — •Knud Seufert, Willi Auwärter, Joachim Reichert, and Johannes V. Barth — Physik Department, TU München, Germany

The reactivity of metalloporphyrins towards small gas molecules is of fundamental interest as it plays for example a key role in the transport of respiratory gases in biological systems. Here we present a comparative low temperature STM and STS study of the interaction of CO and NO with Cobalt-tetraphenylporphyrins (CoTPP) anchored on a Ag(111) surface. The response of CoTPP to the exposure of CO and NO is clearly different: In the CO case, the CoTPP can be dressed by one or two CO ligands. Hereby, the geometric and electronic structure of CoTPP is mostly preserved. The attachment of NO to CoTPP drastically modifies the topographic appearance of CoTPP. The two-fold symmetry of CoTPP resulting from an adsorption-induced distortion is lost upon NO coordination. These experiments were systematically extended to further metalloporphyrins and a Cu(111) surface, to get more information on the underlying bond characteristics.