Dresden 2011 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 63: Ultrakurze Laserpulse: Erzeugung und Anwendungen 2

Q 63.9: Talk

Friday, March 18, 2011, 12:30–12:45, SCH A215

Tip-based electron source for femtosecond electron diffraction — •Jan-Paul Stein, Markus Schenk, Michael Krüger, Peter Baum, and Peter Hommelhoff — Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, 85748 Garching bei München

In today’s femtosecond electron diffraction and microscopy experiments, femtosecond UV pulses are employed to trigger photoemission of electrons from a flat metallic surface cathode. Subsequently, the electrons undergo acceleration in a constant electric field. Due to the limited maximum applicable electric field of roughly 10 MV/m even single electron pulses cannot get shorter than 100 fs at the target [1]. The aim of this study is to replace the flat cathode by a sharp metal tip [2] with a radius of curvature on the order of a few hundred nanometers. Due to the tip geometry the electric field at the apex is strongly enhanced and reaches values of GV/m. Hence electrons experience a strong acceleration right after emission. Electrons leaving the tip with different initial kinetic energies therefore develop a significantly lower timing jitter during their propagation, translating into shorter pulse durations than in conventional setups. Furthermore, the electron beam emittance decreases drastically. We will present results of a detailed analytic and numerical analysis of different setup parameters and discuss the current experimental status.
M. Aidelsburger, F. O. Kirchner et al., PNAS 107 19714 (2010)
P. Hommelhoff, C. Kealhofer et al., Phys. Rev. Lett. 96
  077401 (2006)