A new undulator beamline (P22) for hard X‐ray photoelectron spectroscopy (HAXPES) was built at PETRA III (DESY, Hamburg)
to meet the increasing demand for HAXPES‐based techniques. It provides four special instruments for high‐resolution studies of the electronic and chemical structure of functional nano‐materials and
catalytic interfaces, with a focus on measurements under operando and/or ambient conditions: (i) a versatile solid‐state spectroscopy setup with optional wide‐angle lens and in‐situ electrical
characterization, (ii) a HAXPEEM instrument for sub‐μm spectromicroscopy applications, (iii) an ambient pressure system (> 1 bar) for operando studies of catalytic reactions and (iv) a time‐of‐flight
spectrometer as a full‐field k‐microscope for measurements of the 4D spectral function ρ(EB,k). The X‐ray optics were designed to deliver high brightness photon flux within the HAXPES energy
range 2.4 – 15 keV. An LN2‐ cooled double‐crystal monochromator with interchangeable pairs of Si(111) and (311) crystals is optionally combined with a double channel‐cut post‐monochromator to
generate X‐rays with variable energy bandpass adapted to the needs of the experiment. Additionally, the beam polarization can be varied using a diamond phase plate integrated into the beamline.
Adaptive beam focusing is realized by Be compound refractive lenses and/or horizontally deflecting mirrors down to a spot size of ~20x17 μm2 with a flux of up to 1.1x1013 ph/s (for Si(111) at 6 keV).
