Five-element Johann-type x-ray emission spectrometer with a single-photon-counting pixel detector

Abstract

A Johann-type spectrometer with five spherically bent crystals and a pixel detector was constructed for a range of hard x-ray photon-in photon-out synchrotron techniques, covering a Bragg-angle range of 60°-88°. The spectrometer provides a sub emission line width energy resolution from sub-eV to a few eV and precise energy calibration, better than 1.5 eV for the full range of Bragg angles. The use of a pixel detector allows fast and easy optimization of the signal-to-background ratio. A concentration detection limit below 0.4 wt% was reached at the Cu Kα(1) line. The spectrometer is designed as a modular mobile device for easy integration in a multi-purpose hard x-ray synchrotron beamline, such as the SuperXAS beamline at the Swiss Light Source.

On the sensitivity of hard X-ray spectroscopies to the chemical state of Br

“…Due to the recent developments of highly efficient crystal spectrometers 75,[99][100][101][102][103] , these low-fluorescence-yield features can be collected with acceptable count rates. With the combination of experiment and theory, the valence-to-core emission spectroscopy thus appears as a powerful X-ray technique to probe the chemical state of an element.…”

“…Total fluorescence yield (TFY) spectra were recorded using a 13-element Ge detector. Highenergy-resolution fluorescence-detected XAS (HERFD-XAS) and XES spectra were recorded using the multi-crystal Xray spectrometer of the beamline: the sample, the Si(110) analyzer crystals and a PILATUS 100K 2D detector were placed on 1m diameter Rowland circles 74,75 . In the case of the Kα lines (Kα 1 ≈ 11925 eV), the analyzer crystal was used in an asymmetric mode with the (771) reflection (with an 5.7682 • offset form the (110) direction), and the (880) reflection was chosen for the Br Kβ lines (Kβ 1 ≈ 13291 eV).…”

High energy resolution fluorescence detection XANES – an in situ method to study the interaction of adsorbed molecules with metal catalysts in the liquid phase

“…3 The Pt LIII edge was monitored using High Energy Resolution Fluorescence Detection (HERFD) recently introduced to the SuperXAS beamline of the Swiss Light Source (SLS). 4 This technique has been shown to be very sensitive 5 and able to discriminate adsorption of molecules in 55 gas phase reactions. 6 Ketoisophorone (KIP) and cinnamaldehyde (CIN) were used as probe molecules.…”

Benchmark results and theoretical treatments for valence-to-core x-ray emission spectroscopy in transition metal compounds

“…While the early stages of growth in XES have benefitted from the pioneering work conducted at several synchrotron end-stations, [51,[53][54][55][56][57][58] the relative scarcity of these dedicated beamlines is a serious hurdle to routine application. This has led to continuing effort by several groups to develop laboratory-based XES capabilities.…”