Berlin 2018 – scientific programme
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O: Fachverband Oberflächenphysik
O 12: Ultrafast Electron and spin dynamics at interfaces II
O 12.9: Talk
Monday, March 12, 2018, 17:30–17:45, MA 005
Ultrafast band structure dynamics of thin C60 films on Ag(111) — •Sebastian Emmerich1, Benjamin Stadtmüller1, Dominik Jungkenn1, Norman Haag1, Christina Schott1, Sebastian Hedwig1, Steffen Eich1, Markus Rollinger1, Mahalingam Maniraj1, Martin Aeschlimann1, Mirko Cinchetti2, and Stefan Mathias3 — 1University of Kaiserslautern, Erwin-Schrödinger-Str. 46, 67663 Kaiserslautern, Germany — 2Physikalisches Institut I, Universität Göttingen, 37077 Göttingen, Germany — 3Experimentelle Physik VI, Technische Universität Dortmund, 44221 Dortmund, Germany
The performance of organic based electronic devices is determined by the energy level alignment as well as by the excitation dynamics of electrons in these materials. Although both aspects are intrinsically linked by the polarizability of organic materials, they have mainly been discussed separately so far. In this work, we present new insight into the ultrafast band structure dynamics of thin C60 films on Ag(111). The combination of time- and angle resolved photoemission with a fs-XUV light source allows us to follow the transient evolution of the unoccupied as well as of occupied band structure after the fs-optical excitation with visible light. The unoccupied part of the C60 band structure reveals the well-known quasi-particle dynamics of the exciton formation and its decay in C60. Most interestingly, we observe a transient inhomogeneous broadening of all occupied molecular orbitals upon optical excitation. This effect is attributed to the transient polarization of the molecular film caused by the exciton formation at distinct C60 sites.