FlexPES: a versatile soft X-ray beamline at MAX IV Laboratory

Abstract

FlexPES is a soft X-ray beamline on the 1.5 GeV storage ring at MAX IV Laboratory, Sweden, providing horizontally polarized radiation in the 40–1500 eV photon energy range and specializing in high-resolution photoelectron spectroscopy, fast X-ray absorption spectroscopy and electron–ion/ion–ion coincidence techniques. The beamline is split into two branches currently serving three endstations, with a possibility of adding a fourth station at a free port. The refocusing optics provides two focal points on each branch, and enables either focused or defocused beam on the sample. The endstation EA01 at branch A (Surface and Materials Science) is dedicated to surface- and materials-science experiments on solid samples at ultra-high vacuum. It is well suited not only to all flavours of photoelectron spectroscopy but also to fast (down to sub-minute) high-resolution X-ray absorption measurements with various detectors. Branch B (Low-Density Matter Science) has the possibility to study gas-phase/liquid samples at elevated pressures. The first endstation of this branch, EB01, is a mobile setup for various ion–ion and electron–ion coincidence techniques. It houses a versatile reaction microscope, which can be used for experiments during single-bunch or multi-bunch delivery. The second endstation, EB02, is based on a rotatable chamber with an electron spectrometer for photoelectron spectroscopy studies on primarily volatile targets, and a number of peripheral setups for sample delivery, such as molecular/cluster beams, metal/semiconductor nanoparticle beams and liquid jets. This station can also be used for non-UHV photoemission studies on solid samples. In this paper, the optical layout and the present performance of the beamline and all its endstations are reported.

Critical Step in the HCl Oxidation Reaction over Single-Crystalline CeO2–x(111): Peroxo-Induced Site Change of Strongly Adsorbed Surface Chlorine

“…Up to 200 L of O 2 , a shift by 0.1 eV is observed in the O 1s binding energy, while from 200 to 300 L it additionally shifts by 0.1 eV, remaining then nearly constant for even higher O 2 exposures. For resolving this small energy shift, high resolution at FlexPES is mandatory. More bulk-sensitive O 1s spectra are shown in Figure S7b.…”

“…16−20 The film thickness of stoichiometric CeO 2 (111) is determined by X-ray reflectometry (XRR, PANalytical X'Pert PRO MRD) to be 5.6 nm, corresponding to 18 O−Ce−O trilayers. 10 The stoichiometric CeO 2 (111)-Ru(0001) samples (prepared in the homelab at the JLU) are subsequently transferred to the preparation chamber of the permanent endstation EA01 (Surface and Material Science branch) at the FlexPES beamline 21 at MAX IV in Lund, Sweden. On-site, the CeO 2 (111)-Ru(0001) sample is annealed for t = 15 min in p(O 2 ) = 10 −6 mbar, followed by a quick annealing step to T = 1200 K in p(O 2 ) = 10 −6 mbar to remove potential carbon contamination during the sample transfer.…”

“…acknowledge funding by the DFG (Ov21-19). We acknowledge MAX IV Laboratory for time on Beamline FlexPES under Proposal 20210040. Research conducted at MAX IV, a Swedish national user facility, is supported by the Swedish Research council under contract 2018-07152, the Swedish Governmental Agency for Innovation Systems under contract 2018-04969, and formal under contract 2019-02496.…”

Interface Energy Alignment between Lead Halide Perovskite Single Crystals and TIPS-Pentacene

“…Photoelectron Spectroscopy Measurements and Analysis. PES measurements were carried out at the FlexPES beamline 32 at the MAX IV facility and at the CoESCA endstation at the BESSY II electron storage ring. 33 At FlexPES, the X-rays were generated by a linearly polarized undulator with a period length of 54.4 mm and monochromated using a plane grating monochromator (modified Zeiss SX700).…”

Effect of Different In2O3(111) Surface Terminations on CO2 Adsorption

“…The XPS measurements were performed at the Surface Materials Science branch of the FlexPES beamline at the MAX IV synchrotron . This beamline is dedicated to high-resolution XPS and soft-wavelength X-ray absorption measurements.…”