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O: Fachverband Oberflächenphysik

O 83: Poster Focus Session: Structural Dynamics in Nanoscale Materials, Probed by Ultrafast Electron Pulses

O 83.4: Poster

Mittwoch, 14. März 2018, 18:15–20:30, Poster A

Towards observing dynamics in molecular overlayers using Ultrafast Low Energy Electron Diffraction (ULEED) — •Bareld Wit, Erica Warth Pérez Arias, Theo Diekmann, Gerrit Horstmann, Simon Vogelgesang, Gero Storeck, and Claus Ropers — 4th Physical Institute, University of Göttingen, 37077 Göttingen, Germany

Very recently, we reported the successful implementation of ULEED in backscattering mode. This yielded new insights into the model system of charge density wave dynamics in 1T-TaS2 [1,2]. One of the next challenges is to expand the scope of ULEED to dedicated surface systems for which the structural dynamics cannot be accessed by other time resolved techniques. In this contribution, the progress towards resolving ultrafast dynamics in (sub-)monolayer molecular overlayers on solid substrates will be presented.

As a model system, we have chosen 1,2-bis(4-pyridyl)ethylene (bpe) on graphite. It has been shown that bpe forms ordered islands at sub-monolayer coverages that can reversibly melt at 414K [3]. We can observe this 'order-disorder' transition with LEED. Moreover, since the transition is reversible, it is in principle suited for pump-probe experiments yielding ultrafast structural dynamics.

[1] S. Vogelgesang et al., Nature Phys. doi:10.1038/nphys4309 (2017)

[2] G. Storeck et al., Struct. Dyn. 4, 044024 (2017)

[3] A. Y. Brewer et al., Mol. Phys. 111, 73 (2013)