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HL: Fachverband Halbleiterphysik

HL 30: Poster 2

HL 30.51: Poster

Thursday, September 8, 2022, 11:00–13:00, P3

Measuring ultrashort electron pulse durations by streaking with free electrons — •Lukas Nöding, Arne Ungeheuer, Ahmed Hassanien, Mashood Tariq Mir, Arne Senftleben, and Thomas Baumert — Institute of Physics; Experimental Physics III, Kassel University

Ultrafast electron diffraction is a well-known method for time-resolved measurements on molecules and condensed matter. The duration of the electron pulse directly determines the temporal resolution of the UED setup as it works like the shutter speed of a camera. A streaking setup utilizing free electrons is implemented to measure the duration of the electron pulse. For this, a new measurement device was designed. It consists of an aperture and a metal surface behind the aperture, parallel to the path of the electron pulse. A femtosecond laser pulse is focused onto the metal surface. As the beam incides, electrons are released from the metal surface. Because of their momentum at first, they separate from the surface, create an electric field perpendicular to the surface and then recombine. This short-lived electric field is used to streak the electron pulse. The electron pulse at the front of the pulse should experience a different field strength than the electrons at the end. By that the duration of the pulse is mapped into a spatial extension of the pulse. The spatial and temporal overlap for the electron pulse and the laser beam had to be set exactly. The results are shown with their evaluation and compared to simulations.