Montel mirror based collimating analyzer system for high-pressure resonant inelastic X-ray scattering experiments

Resonant inelastic X-ray scattering (RIXS) is increasingly playing a significant role in studying highly correlated systems, especially since it was proven capable of measuring low-energy magnetic excitations. However, despite high expectations for experimental evidence of novel magnetic phases at high pressure, unequivocal low-energy spectral signatures remain obscured by extrinsic scattering from material surrounding the sample in a diamond anvil cell (DAC): pressure media, Be gasket and the diamond anvils themselves. A scattered X-ray collimation based medium-energy resolution (∼100 meV) analyzer system for a RIXS spectrometer at the Ir L 3-absorption edge has been designed and built to remediate these difficulties. Due to the confocal nature of the analyzer system, the majority of extrinsic scattering is rejected, yielding a clean low-energy excitation spectrum of an iridate Sr2IrO4 sample in a DAC cell. Furthermore, the energy resolution of different configurations of the collimating and analyzing optics are discussed.

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Resonant inelastic X-ray scattering of magnetic excitations under pressure

Journal of Synchrotron Radiation ◽

10.1107/s1600577519008877 ◽

2019 ◽

Vol 26 (5) ◽

pp. 1725-1732 ◽

Cited By ~ 2

Author(s):

Matteo Rossi ◽

Christian Henriquet ◽

Jeroen Jacobs ◽

Christian Donnerer ◽

Stefano Boseggia ◽

...

Keyword(s):

High Pressure ◽

Low Temperature ◽

Energy Resolution ◽

Low Energy ◽

Polarization Analysis ◽

Magnetic Excitations ◽

X Ray ◽

X Ray Scattering ◽

Sample Environment ◽

Ray Scattering

Resonant inelastic X-ray scattering (RIXS) is an extremely valuable tool for the study of elementary, including magnetic, excitations in matter. The latest developments of this technique have mostly been aimed at improving the energy resolution and performing polarization analysis of the scattered radiation, with a great impact on the interpretation and applicability of RIXS. Instead, this article focuses on the sample environment and presents a setup for high-pressure low-temperature RIXS measurements of low-energy excitations. The feasibility of these experiments is proved by probing the magnetic excitations of the bilayer iridate Sr3Ir2O7 at pressures up to 12 GPa.

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Direct tomography imaging for inelastic X-ray scattering experiments at high pressure

Journal of Synchrotron Radiation ◽

10.1107/s1600577516017100 ◽

2017 ◽

Vol 24 (1) ◽

pp. 269-275 ◽

Cited By ~ 14

Author(s):

Ch. J. Sahle ◽

A. D. Rosa ◽

M. Rossi ◽

V. Cerantola ◽

G. Spiekermann ◽

...

Keyword(s):

High Pressure ◽

Machine Learning Algorithms ◽

Raman Scattering Spectroscopy ◽

X Ray ◽

Spatially Resolved ◽

X Ray Scattering ◽

Sample Edge ◽

Pressure Medium ◽

Diamond Anvils ◽

Ray Scattering

A method to separate the non-resonant inelastic X-ray scattering signal of a micro-metric sample contained inside a diamond anvil cell (DAC) from the signal originating from the high-pressure sample environment is described. Especially for high-pressure experiments, the parasitic signal originating from the diamond anvils, the gasket and/or the pressure medium can easily obscure the sample signal or even render the experiment impossible. Another severe complication for high-pressure non-resonant inelastic X-ray measurements, such as X-ray Raman scattering spectroscopy, can be the proximity of the desired sample edge energy to an absorption edge energy of elements constituting the DAC. It is shown that recording the scattered signal in a spatially resolved manner allows these problems to be overcome by separating the sample signal from the spurious scattering of the DAC without constraints on the solid angle of detection. Furthermore, simple machine learning algorithms facilitate finding the corresponding detector pixels that record the sample signal. The outlined experimental technique and data analysis approach are demonstrated by presenting spectra of the SiL2,3-edge and OK-edge of compressed α-quartz. The spectra are of unprecedented quality and both the OK-edge and the SiL2,3-edge clearly show the existence of a pressure-induced phase transition between 10 and 24 GPa.

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