Dresden 2006 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 23: POSTER Functional Organic Thin Films

CPP 23.12: Poster

Thursday, March 30, 2006, 17:00–19:00, P2

Hot Electron Dynamics in Sodium doped PTCDA thin Films — •Jens Wüsten, Steffen Berger, Marc Salomon, Michael Bauer, Stefan Lach, Martin Aeschlimann, and Christiane Ziegler — University of Kaiserslautern, Department of Physics, Erwin-Schrödinger-Straße 56, 67663 Kaiserslautern

Time resolved 2 photon photoemission (2PPE) measurements of the doping process of PTCDA thin films with sodium give insight into the dynamics of hot electrons in this system. Interaction with sodium results in a charge transfer from sodium to PTCDA ("n-doping") and is accompanied by an increase of the lifetime of electrons excited to unoccupied states 1.4 - 1.8 eV above the Fermi level. Supported by DFT-calculations of molecular orbital energies and excited state energies, this result can be explained from a joint physical viewpoint that combines the one electron picture, treated in "classical" photoemission spectroscopy theory, with many electron excitations as commonly considered in optical spectroscopy. As thin PTCDA layers on a Ag(111) surface show up similar features in UV photoelectron spectroscopy as sodium doped PTCDA, this system has also been investigated by 2PPE. An increase of lifetime can be observed for thin PTCDA coverages, which points at a charge transfer from Ag to PTCDA.