Berlin 2015 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 70: Structural Dynamics in Nanoscale Materials Probed by Ultrashort Electron Pulses
O 70.16: Poster
Mittwoch, 18. März 2015, 18:15–21:00, Poster A
Cooperative atomic motion probed by femtosecond electron diffraction — Maximilian Eichberger1 and •Jure Demsar2 — 1Department of Physics, University of Konstanz — 2Institute of Physics, Johannes Gutenberg-University Mainz
Recently, several studies of light-induced suppression or quenching of charge density wave order were performed using ultrafast diffraction methods. This coherent process, which takes place on a 100 femtosecond timescale (a fraction of a period of the corresponding amplitude mode), is accompanied by a rapid sub-picosecond energy transfer to the lattice via strong electron-phonon and phonon-phonon scattering. Both processes, the coherent order parameter dynamics and the incoherent redistribution of energy among different subsystems, affect the diffraction pattern. For their comparable timescales they are hard to distinguish based on the dynamics alone.
Using ultrafast electron diffraction in transmission we show, that by simultaneous tracking the intensities of lattice and super-lattice diffraction peaks for multiple diffraction orders (this being one of the main advantages of ultrafast electron diffraction against femtosecond X-ray methods) the two processes can be effectively disentangled.