Design of an ultrahigh-energy-resolution and wide-energy-range soft X-ray beamline

Abstract

A new ultrahigh-energy-resolution and wide-energy-range soft X-ray beamline has been designed and is under construction at the Shanghai Synchrotron Radiation Facility. The beamline has two branches: one dedicated to angle-resolved photoemission spectroscopy (ARPES) and the other to photoelectron emission microscopy (PEEM). The two branches share the same plane-grating monochromator, which is equipped with four variable-line-spacing gratings and covers the 20-2000 eV energy range. Two elliptically polarized undulators are employed to provide photons with variable polarization, linear in every inclination and circular. The expected energy resolution is approximately 10 meV at 1000 eV with a flux of more than 3 × 10(10) photons s(-1) at the ARPES sample positions. The refocusing of both branches is based on Kirkpatrick-Baez pairs. The expected spot sizes when using a 10 µm exit slit are 15 µm × 5 µm (horizontal × vertical FWHM) at the ARPES station and 10 µm × 5 µm (horizontal × vertical FWHM) at the PEEM station. The use of plane optical elements upstream of the exit slit, a variable-line-spacing grating and a pre-mirror in the monochromator that allows the influence of the thermal deformation to be eliminated are essential for achieving the ultrahigh-energy resolution.

Optimization of the design for beamline with fast polarization switching elliptically polarized undulators

“…This beamline design is given for covering an energy range of 250-2000 eV, which is popular for magnetic research in the soft X-ray range. It has been proposed for ultra-high-energy resolution (Reininger, 2011;Xue et al, 2014). The key point of this design is that a variable line space (VLS) grating is the only vertical focusing optics, which makes it easy to refocus the beam if the incoming beam is unfocused.…”

MAXPEEM: a spectromicroscopy beamline at MAX IV laboratory

“…At NSLS II (Reininger et al, 2012), which hosts a similar instrument, the main difference is the spot size (50 mm) and grazing incidence illumination. At Shanghai Synchrotron Radiation Facility (Xue et al, 2014), an aberration-corrected photoemission electron microscope (AC-PEEM) is used for time-resolved photoelectron microscopy (Li et al, 2019). There are also two non-commercial aberration-corrected PEEM instruments: one is SMART type at BESSY II [a complete version with LEEM function and a dedicated Omega-type energy filter (Schmidt et al, 1998)] and the other one is PEEM3 at the Advanced Light Source (beamline 11.0.1.1).…”

The meV XUV-RIXS facility at UE112-PGM1 of BESSY II

“…Soft X-ray RIXS with a strong focus on the K-edges of nitrogen and oxygen as well as the transition metal L-edges has become a powerful experimental technique with an extensive body of work over the last 20 years (Gel'mukhanov et al, 2021;Ament et al, 2011;Savchenko et al, 2021;Schmitt et al, 2014). In contrast the XUV region ending just above the carbon K-edge (280 eV) has been much less in the focus of investigation and only very few highresolution RIXS stations exist for this energy range (Strocov et al, 2010;Yamane et al, 2013;Xue et al, 2014;Schmitt et al, 2013;Kokkonen et al, 2021;Dziarzhytski et al, 2020). In this region access to the M-edges of transition metals as well as to the N-edges of elements of the lanthanide series is possible in addition to the shallow core levels of highly important elements such as silicon, beryllium, sulfur, phosphor and carbon, to name a few.…”