Dmytro Kutnyakhov, Rui Patrick Xian, Maciej Dendzik, Michael Heber, Federico Pressacco, Steinn Ymir Agustsson, Lukas Wenthaus, Holger Meyer, Sven Gieschen, Giuseppe Mercurio, Adrian Benz, Kevin Bühlman, Simon Däster, Rafael Gort, Davide Curcio, Klara Volckaert, Marco Bianchi, Charlotte Sanders, Jill Atsuko Miwa, Søren Ulstrup, Andreas Oelsner, Christian Tusche, Ying-Jiun Chen, Dmitrii Vasilyev, Katerina Medjanik, Günter Brenner, Siarhei Dziarzhytski, Harald Redlin, Bastian Manschwetus, Shuo Dong, Jasper Hauer, Laurenz Rettig, Florian Diekmann, Kai Rossnagel, Jure Demsar, Hans-Joachim Elmers, Philip Hofmann, Ralph Ernstorfer, Gerd Schönhense, Yves Acremann, and Wilfried Wurth:
Rev. Sci. Instr. 91, 013109 (2020), pp.12;
arXiv:1906.12155 [cond-mat.mtrl-sci] (2019), pp. 12;
DOI: arXiv:1906.12155 [cond-mat.mtrl-sci]
Time-resolved photoemission with ultrafast pump and probe pulses is an emerging technique with a huge 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 fs soft X-ray pulses with some 10~meV 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 spectral resolution 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 the superior source parameters of the beamline with a revolutionary 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 the entire 3D band structure in the (kx, ky, E) parameter space with unprecedented efficiency. Our instrument can image the full surface Brillouin zone with up to 7 Å-1 diameter in a binding-energy range of several~eV, resolving about 2.5×105 data voxels. As an example, we present results for the ultrafast excited state dynamics in a model van der Waals semiconductor WSe2.
The original publication is available by link DOI: 10.1063/1.5118777