Dresden 2017 – scientific programme

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MI: Fachverband Mikrosonden

MI 9: Progress of Instrumentation and Methods for the Surface Analysis (PEEM, LEED)

MI 9.2: Talk

Thursday, March 23, 2017, 11:30–11:45, MER 02

Development of an ultrafast miniaturized low-energy electron gun — •Gero Storeck, Simon Vogelgesang, Murat Sivis, Sascha Schäfer, and Claus Ropers — 4th Physical Institute - Solids and Nanostructures, University of Göttingen, Germany

Ultrafast low-energy electron diffraction was recently shown to be a promising approach to access ultrafast structural dynamics in 2D systems [1]. In order to realize ULEED in a backscattering geometry, we developed several designs of miniaturized pulsed electron guns based on a nanometric tungsten photocathode. Specifically, we fabricate downscaled electron sources with an outer diameter of about 80 µm that allow for a working distance from the sample below several hundred micrometers. A photolithographic process and focused ion beam etching are used to construct the electrostatic gun assembly hosting a nanotip photocathode and a lens for electron beam collimation.

We characterize the low-energy electron pulses by the transient electric field effect and achieve pulse durations down to 1 ps at electron energies as low as 50 eV. This enables us to conduct time-resolved measurements in reflection geometry for the study of ultrafast structural transformations and phase transitions at surfaces.

[1] M. Gulde et al., Science 345, 200 (2014).