Dresden 2011 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 36: Poster Session II (Metals; Nanostructures at surfaces; Surface or interface magnetism; Spin-Orbit Interaction at Surfaces; Electron and spin dynamics; Surface dynamics; Methods; Theory and computation of electronic structure)

O 36.93: Poster

Dienstag, 15. März 2011, 18:30–22:00, P4

The Formation of Shockley derived Interface States at Metal-Organic Interfaces studied with 2PPE — •Manuel Marks¹, Christian H. Schwalb¹, Sönke Sachs², Benjamin Schmidt¹, Achim Schöll², Friedrich Reinert², Eberhard Umbach², and Ulrich Höfer¹ — ¹Fachbereich Physik und Zentrum für Materialwissenschaften, Philipps-Universität Marburg, D-35032 Marburg — ²Universität Würzburg, Experimentelle Physik II, D-97074 Würzburg

The charge carrier injection across a metal-organic interface into the active regions of a functional device is one major influence on the efficiency of organic electronics. New electronic states that emerge at such interfaces can alter these dynamical processes substantially. We applied time- and angle-resolved 2-photon photoemission (2PPE) to study the electron dynamics at structurally well characterized interfaces directly in the time domain. With adsorption of monolayer films of PTCDA and NTCDA on a Ag(111) surface strongly dispersing interface states (IS) form above the Fermi Level E_F. For PTCDA the inelastic electron lifetime of 54 fs indicates a significant overlap with the metal substrate and the state mainly originates from an upshifted Shockley state [1]. For NTCDA films the IS has comparable properties though lying closer to E_F. In the stronger chemisorbed disordered precursor phase of the PTCDA monolayer [2] an interface state emerges at E−E_F=0.45 eV. The lifetime of 63 fs and its non-dispersing behavior raise the question whether this state has more molecular character.
[1] C. H. Schwalb et al., Phys. Rev. Lett. 101, 146801 (2008)
[2] L. Kilian et al., Phys. Rev. Lett. 100, 136103 (2008)