Journal of large-scale research facilities, 7, A140 (2021) http://dx.doi.org/10.17815/jlsrf-7-177 Published: 08.07.2021 PEAXIS: A RIXS and XPS Endstation for Solid- State Quantum and Energy Materials at BESSY II Helmholtz-Zentrum Berlin für Materialien und Energie * Instrument Scientists: - Dr. Deniz Wong, Helmholtz-Zentrum Berlin für Materialien und Energie, phone: +49 30 8062-13485, email: deniz.wong@helmholtz-berlin.de - Dr. Christian Schulz, Helmholtz-Zentrum Berlin für Materialien und Energie, phone: +49 30 8062- 13485, email: schulz-c@helmholtz-berlin.de - Dr. Maciej Bartkowiak, Helmholtz-Zentrum Berlin für Materialien und Energie, phone: +49 30 8062- 13485, email: maciej.bartkowiak@helmholtz-berlin.de Abstract: PEAXIS (Photo Electron Analysis and resonant X-ray Inelastic Spectroscopy) is a dedicated endstation installed at the beamline U41-PEAXIS that o�ers high resolution soft X-ray spectroscopy measurements with incident photon energies ranging from 180 – 1600 eV. The endstation combines two X-ray spectroscopic techniques, X-ray photoelectron spectroscopy (XPS) and resonant inelastic soft X-ray scattering (RIXS), which are important for probing the electronic structure and local and collective excitations of solid-state materials. It features a continuous variation of scattering angle under UHV conditions for wave vector-resolved studies and a modular sample environment that allows investigation in the temperature range between 10 K and 1000 K. 1 Introduction The electronic structure and dynamics of materials determine their fundamental and functional proper- ties which are relevant for technological applications. PEAXIS (Photo Electron Analysis and resonant X-ray Inelastic Spectroscopy) o�ers the possibility of probing electronic states of materials by two sought-after X-ray spectroscopic techniques in one single instrument. The instrument is designed for studying solid-state materials by Resonant Inelastic X-ray Scattering (RIXS) and X-ray Photoelectron Spectroscopy (XPS) and, in addition, allows for the investigation of liquids encapsulated in a sealed *Cite article as: Helmholtz-Zentrum Berlin für Materialien und Energie. (2021). PEAXIS: A RIXS and XPS End- station for Solid-State Quantum and Energy Materials at BESSY II. Journal of large-scale research facilities, 7, A140. http://dx.doi.org/10.17815/jlsrf-7-177 1 http://jlsrf.org/ http://dx.doi.org/10.17815/jlsrf-7-177 http://dx.doi.org/10.17815/jlsrf-7-177 https://creativecommons.org/licenses/by/4.0/ Journal of large-scale research facilities, 7, A140 (2021) http://dx.doi.org/10.17815/jlsrf-7-177 cell. The �xed endstation is installed at the beamline U41-PEAXIS of BESSY II providing monochro- matic, linearly polarized light. The endstation allows for measurements with high energy resolution in combination with a continuous rotation of its 5 m long arm about the sample position. Scattering angles from 33°-139° are thus covered within the horizontal photon scattering plane which enables wavevector-resolved measurements of solid-state samples over a wide wavevector range and, with PEAXIS’ sample manipulators, covering a temperature range from 10 - 1000 K. For sensitive samples, a continuous sample scanning mode is available in order to take measurements with minimal exposure time per surface area while keeping the scattering conditions constant. The instrument is also capa- ble of performing angle-resolved XPS measurements thus allowing to probe the electronic structure of material from surface to bulk. In-house developed software (Centralized Hardware-Overseeing Server, CHaOS and Augmented Data Loading Evaluation Reduction, ADLER) is available to remotely control the experiment and perform a �rst-level analysis of the raw data. This allows users to have real-time feedback on the acquired data that is critical for remote-access experiments. 2 Instrument applications Typical applications: • Magnetic, d-d and charge transfer excitations in model quantum materials and functional energy materials • Dispersive excitations in quantum materials (e.g. plasmons and excitons) • Electron-phonon coupling in solid-state materials • Reaction mechanisms in battery materials 2 http://dx.doi.org/10.17815/jlsrf-7-177 https://creativecommons.org/licenses/by/4.0/ http://dx.doi.org/10.17815/jlsrf-7-177 Journal of large-scale research facilities, 7, A140 (2021) 3 Technical data Source Undulator U41 Horizontal polarization Monochromator 800 l/mm PGM Energy range 180 - 1600 eV (XPS), 200 – 1200 eV (RIXS) Energy resolution/ 311 meV - 24 meV / 3850 - 8250 High-�ux (C� = 2.25, slit = 20 µm) Resolving power 231 meV - 21 meV / 5200 - 9750 Standard (C� = 3, slit = 10 µm) 200 meV - 15 meV / 6000 - 13600 High-resolution (C� = 5, slit = 5 µm) Flux at sample 1.4 x 1011 - 4 x 1012 s−1 (5.7 x 1012 (s−1 x 0.1% BW x 100 mA)) High-�ux mode (@N2 resonance E) Focus at sample 12.4 x 3.8 µm2 (hor. x vert.) Sample size < 10 x 10 mm2, thickness ∼ 1.5 mm Sample 10 - 330 K (closed cycle refrigerator) Low-T manipulator (solid samples) environment 77 - 1000 K (with special holder) High-T manipulator (solid samples) 77 - 370 K Fluid cell (liquid samples) Pressure 10−8 – 10−9 mbar Regular operation Sample movement speed Static, 0.05 mm/s, 0.1 mm/s, 0.2 mm/s Number of samples 6 At load-lock Sample treatment Ar sputtering, annealing, cleaving At load-lock Optics 2 VLS gratings 200 - 600 eV and 400 - 1200 eV Detectors Andor IKON-L CCD 2048 x 2048 pixels with pixel size of 13.5 x 13.5 µm2 RIXS SPECS Phoibos 150 EP XPS Photodiode or sample current XAS Beam availability 12 h/day in units of 1 week Table 1: Technical data of beamline U41-PEAXIS and PEAXIS endstation 3 http://dx.doi.org/10.17815/jlsrf-7-177 https://creativecommons.org/licenses/by/4.0/ Journal of large-scale research facilities, 7, A140 (2021) http://dx.doi.org/10.17815/jlsrf-7-177 Figure 1: View of the PEAXIS endstation. 4 Acknowledgements The project was funded in part by the German BMBF under Förderkennzeichen 05K13KE4. References Lieutenant, K., Hofmann, T., Schulz, C., Yablonskikh, M., Habicht, K., & Aziz, E. F. (2016). Design Concept of the High-Resolution End-station PEAXIS at BESSY II: Wide-Q-Range RIXS and XPS Measurements on Solids, Solutions, and Interfaces. J. El. Spec. Rel. Phen.. http://dx.doi.org/10.1016/j.elspec.2015.08.009 Lieutenant, K., Hofmann, T., Zendler, C., Schulz, C., Aziz, E. F., & Habicht, K. (2016). Numerical optimization of a RIXS spectrometer using raytracing simulations. Journal of Physics: Conference Series. http://dx.doi.org/10.1088/1742-6596/738/1/012104 Schulz, C., Lieutenant, K., Xiao, J., Hofmann, T., Wong, D., & Habicht, K. (2020). Char- acterization of the soft X-ray spectrometer PEAXIS at BESSY II. J. Synchrotron Rad.. http://dx.doi.org/10.1107/S1600577519014887 4 http://dx.doi.org/10.17815/jlsrf-7-177 http://dx.doi.org/10.1016/j.elspec.2015.08.009 http://dx.doi.org/10.1088/1742-6596/738/1/012104 http://dx.doi.org/10.1107/S1600577519014887 https://creativecommons.org/licenses/by/4.0/ Introduction Instrument applications Technical data Acknowledgements