Regensburg 2010 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

O: Fachverband Oberflächenphysik

O 85: Metal substrates: Adsorption of organic / bio molecules VII

O 85.4: Vortrag

Freitag, 26. März 2010, 12:00–12:15, H36

Combined STM and theoretical first-principles study of ligated metalloporphyrins adsorbed on noble metal surfaces — •Knud Seufert¹, Willi Auwärter¹, Marie-Laure Bocquet², Nicolas Lorente³, Alexander Weber-Bargioni⁴, Joachim Reichert^1,4, and Johannes V. Barth¹ — ¹Physik Department, E20, Technische Universität München, Garching, Germany — ²Laboratoire de Chimie, ENS, Lyon, France — ³CIN2, Barcelona, Spain — ⁴Physics Department, University of British Columbia, Vancouver, Canada

Motivated by the importance of metalloporphyrins in many biological processes, such as the transport of respiratory gases, we present a combined experimental and theoretical study of the interaction of gaseous ligands with porphyrins. The metalloporphyrins (M-TPP, M=Fe, Co) were anchored on Ag(111) and Cu(111) surfaces and exposed to small amounts of CO and NO. Based on low-temperature STM experiments, we discuss the M-TPP's appearance and electronic structure dependent on the additional ligand. On both surfaces, bare M-TPPs show an occupied electronic state (HOMO) and an ant-like topographic appearance, which is completely modified through the attachment of NO. The dosage of CO instead yields no drastic changes in the low-energy electronic structure of the porphyrin host.

Our theoretical investigations focus on the well defined Co-TPP/Cu(111) system. The results show that the CO is not exclusively bound to the metal center, but rather to bridge-like positions between the central metal ion and the nitrogen of the porphyrin macrocycle.