Spectroscopy Group Update 2023-24

The spectroscopy group

A significant part of the activities of the spectroscopy group last year has been focussed on specifying the required work needed to ensure that the beamlines remain operational within Diamond-II.  Aside from the work done on SWIFT (see section below), work has progressed on B18 and I20. B18 will benefit from a new 3-pole wiggler source that will replace the existing bending magnet, and as a consequence, new optical components and changes in the end-station position are required. The conceptual design review of the beamline was successfully delivered, and the detailed technical design is now in progress. In the case of I20-Scanning, the wiggler source will not be changed, but the first two mirrors of the beamline will need to be replaced to ensure that they can cope with the increased heat-load delivered by Diamond-II.

The B18 Team : Thokozile Kathyola, Donato Decarolis, Iuliia Mikulska, Sam Embling, Diego Gianolio, Veronica Celorrio

The Core EXAFS beamline, B18, is optimised for the efficient collection of XAS covering a wide energy range. The focussing optics and the capability of the monochromator for continuous scanning, together with a flexible experimental space that supports a large range of sample environment equipment, make this beamline ideal for experiments that are performed under in situ and operando conditions.

Last year, the diffraction detection capabilities of the beamline were enhanced with the procurement of a pixellated Lambda detector. The small footprint of the new detector enables the measurement of XRD at low angles, increasing the angular range covered by the already available Dectris detector. In addition, and following the observed degradation in the performance of the 36-element germanium fluorescence detector, a new multi-element germanium detector has been ordered. The new detector will enable faster measurements and/or the measurement of more dilute samples, while providing better energy resolution than the existing instrument. It is expected that the new detector will be delivered by the end of 2024.

Last year’s developments have been mainly directed towards increasing the efficiency and user friendliness of the beamline. Thus, a new diagnostic tool hasbeen implemented allowing the measurement of calibration foils simultaneously with the data collection when experiments are performed in fluorescence mode, providing an internal energy calibration. In addition, the capability for acquiring quick 2D scans has been included in the data analysis software, removing the need for step scanning when aligning the sample.

The I18 team: Konstantin Ignatyev, Steve Keylock, Susan Nehzati, Tina Geraki and Rhiannon Boseley

The Microfocus Spectroscopy Beamline, I18, is optimised for the study of heterogenous samples using a variety of experimental techniques such as X-ray Fluorescence (XRF) and X-ray Diffraction (XRD) imaging, micro X-ray Absorption Spectroscopy (microXAS), and XRF and XRD micro-tomography (microCT).

The in-house X-ray Emission Spectrometer was commissioned with beam in the last run of 2023 and received its first users in January 2024. The first experiment was successfully performed at the uranium M4 edge to collect HERFD-XANES spectra and RIXS maps, expanding the capabilities of the group in photon-in/photon-out spectroscopy to the tender X-ray regime. In addition, and taking advantage of the tightly focussed beam available on I18, the spectrometer will also enable spatially resolved XES measurements. Besides the uranium Mβ line, analyser crystals covering the Mβ line of thorium and the Kα line of Co, Ni, Cu and Zn are available, while we are planning to procure new crystals offering further coverage if demand is sufficient.

Last year effort has been dedicated to increasing the speed of the data collection. By using the ODIN framework, it is now possible to collect and process XRF data at the maximum rate of 4 kHz, i.e. at a scanning speed of 250 microseconds per pixel, four times faster than before.

The I20 team: Nitya Ramanan, Luke Higgins, Shu Hayama, Darren Neville and Alan Qi

I20-Scanning is a high-flux wiggler beamline optimised for X-ray Absorption Spectroscopy (XAS) and X-ray Emission Spectroscopy (XES) measurements with high energy stability and reproducibility. The XAS end-station is equipped with a multi-element germanium detector that enables the structural study of low concentration samples in fluorescence detection mode. The XES end-station is based on a 1m Rowland circle point-to-point spectrometer and is used to perform High-Energy-Resolution Fluorescence Detection XANES (HERFD-XANES) and Resonant and non-resonant X-ray Emission Spectroscopy (RXES and XES) to study the electronic structure of materials.

In April 2023, the newly commissioned fourteen-analyser spectrometer received its first users, and since then, more than twenty user experiments have been successfully performed. The new spectrometer has been designed to enable the capability for measuring two different emission lines (two-colour operation mode) simultaneously, and many user groups have taken advantage of this unique feature, collecting Kα HERFD-XANES and valence-to-core XES of the same element, or XES data of two different elements. The quick-XES acquisition mode that allow XES features to be measured in a time-resolved manner is in the commissioning phase. This unique capability requires the use of a new motion controller to move many stages in a continuous, coordinated manner and is expected to be available for users in the summer of 2024.

The project aimed at developing a new four-bounce monochromator to extend the energy range of the beamline to 34 keV has made significant progress in the last year. The new generation of motion controllers is currently undergoing performance evaluation, and a prototype crystal stage is under development. The four-bounce monochromator will be the first instrument at Diamond to use directly cooled liquid nitrogen crystals, and the development will be used for other monochromators such as the device being designed for SWIFT. The development work is expected to be completed this year, when the next phase of in-house design work and the build of the instrument will start.

The SWIFT team

SWIFT (Spectroscopy WithIn Fast Timescales) is a new spectroscopy beamline that is being built as part of the Diamond-II upgrade programme. SWIFT will be a wiggler-based, quick-scanning EXAFS beamline dedicated to operando studies, also at micrometric scale. SWIFT will become operational on Diamond-II after the dark period, and is scheduled to be available to the user community in December 2029.

The design phase of SWIFT has progressed through the Technical Design Review, where the specifications for the beamline have been defined and agreed. This is an important milestone as it has enabled the project to progress to the construction phase. The SWIFT delivery plan is very tight, with very little allowance for delays, as the aim is for SWIFT to have all the optical components and end-stations installed before the start of the Diamond-II dark period, anticipating the need for resources that will then be focused on the upgrade of the Diamond operational beamlines.

The procurement of major components for SWIFT has already started. The contract for the construction of the hutches has been placed, and this work is scheduled to be completed by June 2025. The specification of the cabins and services will start after the summer of 2024.

Substantial progress has also been made on the development of the Quick-EXAFS monochromator, a critical area of technical development for SWIFT. Preliminary tests of the fast-scanning mechanism were successful, and the high-load channel-cut crystal prototype has been manufactured and is ready for testing.

Last year significant effort was devoted to specifying the software for SWIFT, which will be entirely based on the new BlueSky architecture. The Specifications Gathering phase is on-going, and the resulting findings will form the foundation for the development of the control, acquisition and analysis stack to be used in the beamline.

Aside from supporting the beamlines and the operational science programmes, the Spectroscopy Group has continued its effort to support the development of the spectroscopy user community.

The annual three-day X-ray Absorption Spectroscopy workshop was run on-site in June 2023. As was the case in previous years, the workshop was in high demand, with more than 160 applications, although required staff-to-student ratios limited the successful applications to 30 participants. The workshop was very successful, and the feedback from the students was very positive.

The group is also invested in enhancing the capabilities of the spectroscopy community in advanced data analysis. With this aim, Diamond, through the Spectroscopy Group, is a partner on the UK High-End Computing Consortium for X-ray Spectroscopy (HPC-CONEXS), an Engineering and Physical Sciences Research Council (EPSRC) funded High End Computing Consortium that will take the lead in the development and distribution of computational tools to advance the detailed analysis of experimental spectroscopy data. The launch of HPC-CONEXS took place in April 2023, together with the final event for the very successful COllaborative NEtwork for X-ray Spectroscopy (CONEXS), its predecessor. The event took place in Oxford and attracted more than 75 attendees, both national and international. As part of the HPC-CONEXS activities, a two-day sandpit was organised in February 2024 at Harwell. During the event, more than 50 attendees had the opportunity to develop and strengthen connections with theorists and/or experimentalists working in X-ray Spectroscopy.

I18: Serpentinization Offers Clues to the Early History of Mars

B18: Synchrotron studies show balance is the key to catalysing methanol production

I20-EDE: Exploring the Dynamics of Catalysis: Single Atoms vs. Nanoparticles

I20-Scanning: From Plant Waste to Petrol Tanks: Using Nature's Solution to Break Down Biomass