Design and performance of AERHA, a high acceptance high resolution soft x-ray spectrometer

Abstract

A soft x-ray spectrometer based on the use of an elliptical focusing mirror and a plane varied line spacing grating is described. It achieves both high resolution and high overall efficiency while remaining relatively compact. The instrument is dedicated to resonant inelastic x-ray scattering studies. We set out how this optical arrangement was judged best able to guarantee performance for the 50 - 1000 eV range within achievable fabrication targets. The AERHA (adjustable energy resolution high acceptance) spectrometer operates with an effective angular acceptance between 100 and 250 μsr (energy dependent) and a resolving power well in excess of 5000 according to the Rayleigh criterion. The high angular acceptance is obtained by means of a collecting pre-mirror. Three scattering geometries are available to enable momentum dependent measurements with 135°, 90°, and 50° scattering angles. The instrument operates on the Synchrotron SOLEIL SEXTANTS beamline which serves as a high photon flux 2 × 200 μm(2) focal spot source with full polarization control.

Extending resonant inelastic X-ray scattering to the extreme ultraviolet

“…The line shapes resolved from SrCuO 2 illustrate the need for adequate resolution to observe how simple atomic excitations decompose into more complex and delocalized many-body states, and are broad enough to also be well resolved at recently developed soft X-ray RIXS spectrometers that achieve ∼100 meV resolution [46][47][48][49]. Our earlier EUV studies have shown that orbital excitations inside the insulating gap of CoO and NiO have significantly sharper line shapes that are sensitive to thermal fluctuations [7], with a δE ∼ 70 meV leading edge contour identified at low temperature for the 1 eV excitation in CoO.…”

Highly efficient soft X-ray spectrometer based on a reflection zone plate for resonant inelastic X-ray scattering measurements

“…Light elements, however, are the building blocks of all compounds relevant in biology and life research. Additionally, the detection efficiency of soft X-ray spectrometers is also low due to grazing incidence gratings and long distances between source and optical element, which lead to a very small solid angle [13][14][15]. This results in a need for brilliant light sources.…”

“…Depending on the experimental requirements, some reach theoretically high resolution up to E/ΔE = 10 5 . However, these are very large instruments with up to 15 m arm length [14,19,20,[22][23][24][25][26]. Other spectrometer designs use additional optical elements to increase the solid angle, e.g.…”

“…This results in a need for brilliant light sources. Soft X-ray spectrometers based on gratings in Rowland circle design or varied line spacing gratings are well-established instrumentation around the world [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]. Depending on the experimental requirements, some reach theoretically high resolution up to E/ΔE = 10 5 .…”

A new compact soft x-ray spectrometer for resonant inelastic x-ray scattering studies at PETRA III

“…[5][6][7][8][9][10][11][12][13] In recent years, new high resolution soft X-ray spectrometers based on varied line spacing gratings have been build. [20][21][22][23][24][25] Some are even able to resolve vibrational states in the spectrum. 26 Yet, they are huge setups with detector arm length of up to 5 m. 22 Future spectrometer projects are even planned with detector arm length up to 15 m with the aim to reach higher resolving power.…”