Freiburg 2024 – scientific programme
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A: Fachverband Atomphysik
A 25: Poster IV
A 25.28: Poster
Wednesday, March 13, 2024, 17:00–19:00, Tent A
Enhancing spectroscopic resolution for coherent control of photoionization with a novel XUV photon spectrometer — •Harijyoti Mandal1, Muwaffaq Ali Mourtada1, Alexander Magunia1, Weiyu Zhang1, Yu He1, Hannes Lindenblatt1, Florian Trost1, Lina Hedewig1, Cristian Medina1, Arikta Saha1, Marc Rebholz1, Ulrike Frühling2, Carlo Kleine1, Gergana D. Borisova1, Steffen Palutke2, Evgeny Schneidmiller2, Mikhail Yurkov2, Stefan Düsterer2, Rolf Treusch2, Chris H. Greene3, Yimeng Wang3, Robert Moshammer1, Christian Ott1, and Thomas Pfeifer1 — 1Max-Planck-Institut für Kernphysik, 69117 Heidelberg, Germany — 2Deutsches Elektronen Synchrotron DESY, 22607 Hamburg, Germany — 3Purdue University, West Lafayette, IN 47907, USA
Extreme-ultraviolet (XUV) free-electron lasers (FELs) can be used for nonlinear multiphoton excitation or ionization of atoms and molecules. Interfering pathways of the second harmonic of the FEL pulses can be used for coherent control experiments, however their spectral content is typically not measured, which is particularly important for stochastic FEL pulses with spectral fluctuations from shot to shot. We present a novel XUV photon spectrometer capable of simultaneously measuring fundamental (ω) and second harmonic (2ω) of FEL spectra. The spectrometer is installed at FLASH, Hamburg, and operates at a repetition rate of 100 kHz. We use phosphor screens and out-of-vacuum imaging onto two GOTTHARD detectors, allowing us to resolve the intrinsic spectral pulse structure of both ω and 2ω FEL pulses. Using a reaction microscope we measured the three-dimensional momentum distributions of helium recoil ions by tuning FLASH in the vicinity of intermediate singly excited states.