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Q: Fachverband Quantenoptik und Photonik

Q 29: Poster I

Q 29.25: Poster

Dienstag, 3. März 2009, 16:30–19:00, VMP 8 Foyer

Characterization of an Ultrafast Electron Diffraction Machine — •Christian Gerbig, Cristian Sarpe–Tudoran, Matthias Wollenhaupt, and Thomas Baumert — Universität Kassel, Institut für Physik und CINSaT, D–34132 Kassel, Germany

In the recent past Ultrafast Electron Diffraction (UED) has become one of the most promising methods to directly provide insights into fundamental physical and chemical dynamics at the microscopic level and on the picosecond to subpicosecond time scale [1,2].
UED as a pump-probe technique typically consists of four stages, the first of which is photoemission of electrons from a photocathode by an ultrashort laser pulse. The second is acceleration and propagation of the electrons towards the specimen; the third is the variable delayed excitation of the specimen by a femtosecond laser pulse (pump) and subsequent diffraction of the electron bunch (probe). In the last stage the diffraction pattern is mapped onto a detector.
In this contribution we present the setup and construction of an apparatus for time-resolved UED measurements based on an amplified 25 fs Ti:Sapphire laser system. First static diffraction patterns of solid state specimens and two concepts for the electron pulse duration determination (electron-electron and electron-laser cross correlation [1]) are presented. In addition, we show improvements and a new approach related to the last three stages (see above) of our UED setup, leading to a better experimental resolution in space and time.
[1] J. R. Dwyer et al., Phil. Trans. R. Soc. A 364 (2006) 741
[2] A. H. Zewail, Annu. Rev. Phys. Chem. 57 (2006) 65