Time- and momentum-resolved photoemission studies using time-of-flight momentum microscopy at a free-electron laser

Time- and momentum-resolved photoemission studies using time-of-flight momentum microscopy at a free-electron laser

Review of Scientific Instruments 91, 013109 (2020) Time-resolved photoemission with ultrafast pump and probe pulses is an emerging technique with wide application potential. Real-time recording of non-equilibrium electronic processes, transient states in chemical reactions or the interplay of electr...

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Main Authors: Kutnyakhov, Dmytro, Xian, Rui Patrick, Dendzik, Maciej, Heber, Michael, Pressacco, Federico, Agustsson, Steinn Ymir, Wenthaus, Lukas, Meyer, Holger, Gieschen, Sven, Mercurio, Giuseppe, Benz, Adrian, Bühlman, Kevin, Däster, Simon, Gort, Rafael, Curcio, Davide, Volckaert, Klara, Bianchi, Marco, Sanders, Charlotte, Miwa, Jill Atsuko, Ulstrup, Søren, Oelsner, Andreas, Tusche, Christian, Chen, Ying-Jiun, Vasilyev, Dmitrii, Medjanik, Katerina, Brenner, Günter, Dziarzhytski, Siarhei, Redlin, Harald, Manschwetus, Bastian, Dong, Shuo, Hauer, Jasper, Rettig, Laurenz, Diekmann, Florian, Rossnagel, Kai, Demsar, Jure, Elmers, Hans-Joachim, Hofmann, Philip, Ernstorfer, Ralph, Schönhense, Gerd, Acremann, Yves, Wurth, Wilfried
Format: Journal Article
Language:English
Published: 18-09-2019
Subjects:
Physics - Materials Science
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Summary:Review of Scientific Instruments 91, 013109 (2020) Time-resolved photoemission with ultrafast pump and probe pulses is an emerging technique with wide application potential. Real-time recording of non-equilibrium electronic processes, transient states in chemical reactions or the interplay of electronic and structural dynamics offers fascinating opportunities for future research. Combining valence-band and core-level spectroscopy with photoelectron diffraction for electronic, chemical and structural analysis requires few 10 fs soft X-ray pulses with some 10 meV spectral resolution, which are currently available at high repetition rate free-electron lasers. The PG2 beamline at FLASH (DESY, Hamburg) provides a high pulse rate of 5000 pulses/s, 60 fs pulse duration and 40 meV bandwidth in an energy range of 25-830 eV with a photon beam size down to 50 microns in diameter. We have constructed and optimized a versatile setup commissioned at FLASH/PG2 that combines FEL capabilities together with a multidimensional recording scheme for photoemission studies. We use a full-field imaging momentum microscope with time-of-flight energy recording as the detector for mapping of 3D band structures in ($k_x$, $k_y$, $E$) parameter space with unprecedented efficiency. Our instrument can image full surface Brillouin zones with up to 7 {\AA} $^{-1}$ diameter in a binding-energy range of several eV, resolving about $2.5\times10^5$ data voxels. As an example, we present results for the ultrafast excited state dynamics in the model van der Waals semiconductor WSe$_2$.
DOI:10.48550/arxiv.1906.12155