Regensburg 2025 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 7: Focus Session Ultrafast Electron Microscopy at the Space-Time Limit I

O 7.5: Vortrag

Montag, 17. März 2025, 11:45–12:00, H11

Time-resolved momentum microscopy with fs-XUV photons at high repetition rates with flexible energy and time resolution — •Karl Schiller¹, Lasse Sternemann¹, Matija Stupar¹, Alan Omar², Martin Hoffmann², Jonah Nitschke¹, Valentin Mischke¹, David Janas¹, Stefano Ponzoni^1,3, Giovanni Zamborlini^1,4, Clara Saraceno², and Mirko Cinchetti¹ — ¹TU Dortmund University, Dortmund, Germany — ²Ruhr University Bochum, Germany — ³Ecole Polytechnique, Paris, France — ⁴Karl-Franzens-University Graz, Austria

We present a versatile setup for time-resolved ARPES that combines an energy-filtered momentum microscope with a custom-designed high-harmonic generation (HHG) photon source [1]. The HHG source is powered by a commercial multi-100 kHz Yb-based ultrafast laser system delivering femtosecond pulses in the extreme ultraviolet range. A nonlinear pulse compression stage, utilizing spectral broadening in a Herriott-type bulk multi-pass cell, enables flexible control of the driving pulse duration. This adaptability allows two distinct operational modes, optimized for either energy or time resolution, making the setup highly suitable for ultrafast photoelectron microscopy at the space-time limit. We demonstrate the system’s capabilities by tracking conduction band dynamics in the valleys of a bulk WS₂ crystal. Using uncompressed laser pulses, we achieve an energy resolution better than (107 ± 2) meV. Compressed pulses, in contrast, yield a time resolution of (48.8 ± 17) fs.

[1] Optica Open Preprint 115282 (2024)

Keywords: trARPES; High harmonic generation; WS2