B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS
Optics
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Wai Jue
Tan
,
Arindam
Majhi
,
Wadwan
Singhapong
,
Andrew C.
Walters
,
Matthijs A.
Van Spronsen
,
Georg
Held
,
Burcu
Karagoz
,
David C.
Grinter
,
Pilar
Ferrer
,
Guru
Venkat
,
Qiushi
Huang
,
Zhe
Zhang
,
Zhanshan
Wang
,
Patrick Yuheng
Wang
,
Andrey
Sokolov
,
Hongchang
Wang
,
Kawal
Sawhney
Open Access
Abstract: X-ray Photoelectron Spectroscopy (XPS) is a powerful tool for probing the chemical and electronic states of materials with elemental specificity and surface sensitivity. However, its application in the tender X-ray range (1–5 keV) for synchrotron radiation has remained limited due to the limited choice of optics capable of maintaining high reflectivity and efficiency in this energy window. To address this, multilayer (ML) grating structures have become increasingly popular, offering significantly higher efficiency than SL coatings in the tender X-ray region. This paper presents the development of ML laminar gratings optimised for enhancing efficiency in the tender X-ray range, and capable of retaining performance under intense X-ray exposure in the oxygen partial pressure of 10 mbar. The ML coating quality was verified through X-ray reflectivity (XRR), XPS and near-edge X-ray absorption fine structures (NEXAFS) measurements, while the performance of the grating was validated through beamline flux transmission and XPS measurements. The MLLG demonstrated 22 higher intensity in flux and XPS, significantly improving the signal-to-noise ratio. Most importantly, the MLLGs outperformed traditional designs by offering improved spectral resolution while maintaining measurement capability at varying values without compromising the intensity. Furthermore, we demonstrated that the incorporation of nitrogen during deposition further enhances flux transmission.
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Oct 2025
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B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
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Jonathan R.
Thurston
,
Shuya
Li
,
Qi
Sun
,
Dennis
Nordlund
,
Luis
Kitsu Iglesias
,
Collin
Sindt
,
Santosh
Kumar
,
David C.
Grinter
,
Hong
Li
,
Ann L.
Greenaway
,
Elisa M.
Miller
,
Michael F.
Toney
Diamond Proposal Number(s):
[35956]
Abstract: P(NDI2OD-T2), commonly referred to as N2200, stands out as a promising electron-transporting (n-type) polymer for low-cost, flexible (photo)electrochemical applications due to its reversible two-electron reduction and high electron mobility. UV–vis spectroelectrochemistry in the tetrabutyl ammonium hexafluorophosphate/acetonitrile electrolyte shows two sets of chemically reversible redox signals in the cyclic voltammetry corresponding to the reduction of the neutral polymer film to polaronic and bipolaronic species. These electrochemical signatures suggest a distinct electronic reorganization upon reduction (polaron/bipolaron formation), highlighting the need for molecular-level insights into how charges are accommodated within the polymer backbone. While it has been previously hypothesized that charge predominantly localizes on the naphthalene diimide (NDI) unit during reductive charging, specific changes in atomic environments that confirm this localization have not been characterized in n-type polymers. Herein, we use near-edge X-ray absorption fine structure (NEXAFS) spectroscopy to probe electronic transitions in an electrochemically charged polymer to deduce charge localization. The O K-edge (1s) spectra exhibit two distinct π* peaks; the intensity of the lower-energy π*a peak that corresponds to an excitation to a largely localized carbonyl state decreases with reductive potentials relative to the higher-energy π*b peak. We corroborate this with Raman spectroscopy at different potentials, which shows a decrease in intensity on the C–C/C═C and C═O stretching bands of NDI as well as a red shift of the carbonyl band due to the formation of a polaron on the NDI. Additionally, new Raman active NDI signals associated with elongated C═O and C═C bonds are observed at lower energy during the formation of charged states. Together with theoretical calculations, these findings show that the injected charge spatially localizes on the NDI units and is dominantly distributed on the carbonyl groups. The combination of NEXAFS, optical and vibrational spectroscopies, and theoretical calculations is generalizable to other pi-conjugated polymers and can identify charge localization for the further development of organic semiconductors.
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Oct 2025
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B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
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Diamond Proposal Number(s):
[40403]
Open Access
Abstract: This study explores the effect of CeO2 doping on the catalytic performance of Fe, Co, and Ni catalysts supported on carbon nanofibers (CNFs) for hydrogen production via ammonia decomposition. Incorporating CeO2 significantly enhanced catalytic activity, achieving 90 % ammonia conversion at 600 °C. Stability tests confirmed sustained performance, maintaining high activity for at least 30 h on stream. A deep surface characterization revealed that the incorporation of Ni after the CeO2 doping created nanocatalytic portions of highly dispersed Ni/CeO2 on the CNFs structure. This guaranteed an intimate contact between the Ni and the CeO2, resulting in an increase in the H2 production rate. Notably, Ni catalysts directly supported on bulk CeO2 exhibited inferior performance, likely due to low relative surface of available ceria. These findings highlight CeO2-doped CNFs as a promising platform for scalable, high-performance hydrogen production from ammonia.
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Sep 2025
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B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
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Diamond Proposal Number(s):
[37075]
Open Access
Abstract: Synchrotron-based near-edge X-ray absorption fine structure (NEXAFS) spectroscopy has been used to investigate a novel Sn:SiO2 composite thin layer grown by organometallic chemical vapor deposition technique (CVD) on a single crystalline silicon wafer with additional treatment by argon ions. According to a previously reported thermodynamic anomaly, an efficient exchange of oxygen between the silicon and tin dioxide surfaces occurs during the growth of the metal oxide thin layer. The present study focuses on the visualization of the atomic and electronic structure of tin nanostructures localized in silica matrix. It is found that no significant chemical alterations are observed during argon ions treatment of the initial composite layer. The removal of atmospheric residues, which partially passivated defects in the highly defective SnO2-x top layer, did not significantly change the initial NEXAFS Sn M4,5 edge spectrum. Based on these results, we found that the main state in which tin nanoparticles localized in the amorphous silica matrix is the metallic state. In addition based on the NEXAFS Si L2,3-edge studies, we found that silica is most associated with the stoichiometric structure of thermally deposited SiO2 layer with the presence of silicon suboxides. These results provide insights into the atomic and electronic structure of Sn:SiO2 composites and contribute to the possible implementation of such materials in various application concepts related to thermal energy storage and novel photonic devices.
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Jun 2025
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B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
B18-Core EXAFS
I14-Hard X-ray Nanoprobe
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Lotfi
Boudjema
,
Anil Kumar
Dahiya
,
Ivan
Da Silva
,
Diego
Gianolio
,
Izuchika
Nduka
,
Manfred Erwin
Schuster
,
Gea T.
Van De Kerkhof
,
Paulina
Kalinowska
,
Emilio
Borrego-Marin
,
Jorge A. R.
Navarro
,
Valentina
Colombo
,
June
Mccorquodale
,
David C.
Grinter
,
Pilar
Ferrer
,
Georg
Held
,
C. Richard A.
Catlow
,
Rosa
Arrigo
Diamond Proposal Number(s):
[28630]
Open Access
Abstract: We investigate the rapid microwave-assisted solvothermal synthesis of a Cu-MOF (Metal-Organic Framework) with open metal sites, with a focus on understanding its CO2 capture properties in relation to phase purity and stability. A combined experimental and theoretical approach is used to identify the MOF structural features involved in the adsorption process. Specifically, Cu(I) defects are found playing an important role in the CO2 adsorption process, with the Cu-1 sample, synthesized using an optimized ligand/Cu precursor ratio for highest phase purity, exhibiting more abundant Cu(I) defects as well as highest adsorption capacity. Grand Canonical Monte Carlo simulations show that the Cu(I) sites exhibit a greater affinity for CO2 adsorption compared to the Cu(II) sites. In situ spectroscopic soft and hard X-ray absorption fine structure spectroscopy confirm the conversion of Cu(I) to Cu(II) upon CO2 chemisorption, with this conversion being more pronounced in the core of the particles. The simulations are used to estimate the fraction of Cu(I) defects and Cu(II) sites present within the Cu-1 MOF and to validate the experimental isotherm. Overall, this study provides insights into the CO2 capture properties of GIF-KUC Cu-MOFs and highlights the importance of phase purity for achieving high adsorption performance.
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Jun 2025
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B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
I09-Surface and Interface Structural Analysis
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Nickil
Shah
,
Galo J.
Paez Fajardo
,
Hrishit
Banerjee
,
Gaurav C.
Pandey
,
Ashok S.
Menon
,
Muhammad
Ans
,
Veronika
Majherova
,
Gerard
Bree
,
Satish
Bolloju
,
David .
Grinter
,
Pilar
Ferrer
,
Pardeep K.
Thakur
,
Tien-Lin
Lee
,
Melanie
Loveridge
,
Andrew J.
Morris
,
Clare P.
Grey
,
Louis F. J.
Piper
Diamond Proposal Number(s):
[30201, 33459]
Open Access
Abstract: In Ni-rich layered oxide cathodes, cycling above the oxygen-loss threshold voltage (∼4.3 V vs Li+/Li) promotes structural transformations at the cathode surface. These transformations can result in various thermodynamically favorable rocksalt-like (RSL) structures (NiO, NiOx, and/or LiyNizO) that have different Li+ transport properties. Elucidating the precise phase type in the RSL can help determine design strategies to improve Li+ kinetics and identify design rules to suppress capacity fade in Ni-rich cathodes. This study utilizes surface-sensitive X-ray absorption spectroscopy in combination with first-principles simulations and distinguishes the layered oxide spectroscopic features from those of surface-reduced layers of pure NiO and LixNi1–xO. The transport of lithium ions through this oxygen-loss-induced surface-reconstructed layer is studied with operando X-ray diffraction in a pouch cell as a function of cycling aging and constant voltage protocols.
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Feb 2025
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B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
I10-Beamline for Advanced Dichroism - scattering
I20-Scanning-X-ray spectroscopy (XAS/XES)
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Lijin
An
,
Ruomu
Zhang
,
Prvanin N.
Didwal
,
Michael W.
Fraser
,
Leanne A. H.
Jones
,
Conor M. E.
Phelan
,
Namrata
Ramesh
,
Grant
Harris
,
Robert S.
Weatherup
,
Jack E. N.
Swallow
,
Peixi
Cong
,
Andrey
Poletayev
,
Erik
Bjorklund
,
Christophe J.
Sahle
,
Pilar
Ferrer
,
David C.
Grinter
,
Peter
Bencok
,
Shusaku
Hayama
,
Saiful
Islam
,
Robert
House
,
Peter D.
Nellist
,
Robert J.
Green
,
Rebecca J.
Nicholls
Diamond Proposal Number(s):
[33283, 33062, 32010]
Open Access
Abstract: Ni-rich layered oxide cathodes can deliver higher energy density batteries, but uncertainties remain over their charge compensation mechanisms and the degradation processes that limit cycle life. Trapped molecular O2 has been identified within LiNiO2 at high states of charge, as seen for Li-rich cathodes where excess capacity is associated with reversible O-redox. Here we show that bulk redox in LiNiO2 occurs by Ni-O rehybridization, lowering the electron density on O sites, but importantly without the involvement of molecular O2. Instead, trapped O2 is related to degradation at surfaces in contact with the electrolyte, and is accompanied by Ni reduction. O2 is removed on discharge, but excess Ni2+ persists forming a reduced surface layer, associated with impeded Li transport. This implicates the instability of delithiated LiNiO2 in contact with the electrolyte in surface degradation through O2 formation and Ni reduction, highlighting the importance of surface stabilisation strategies in suppressing LNO degradation.
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Sep 2024
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B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
I10-Beamline for Advanced Dichroism - scattering
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Diamond Proposal Number(s):
[33639, 34919, 36558]
Open Access
Abstract: Spinel ferrites exhibit significant promise in photocatalysis and other applications due to their compositional diversity and favourable electronic structure, magnetism, and partially tuneable cation distribution. However, their complex properties, for example, the different behaviour of bulk and nanostructured materials, are not well understood. Here, we combine advanced computational and experimental methods with reactivity measurements to explore the inversion degrees, electronic structures, and photocatalytic activities of MFe2O4 spinels (M = Co, Cu, Zn). X-ray diffraction and anomalous X-ray scattering measurements determined bulk inversion degrees of 0.81, 0.91, and 0.26 for CoFe2O4, CuFe2O4, and ZnFe2O4, respectively. Photocatalytic tests showed that only ZnFe2O4 is active in the oxygen evolution reaction (OER), which correlates with its favourable band alignment, as determined through electronic structure simulations. Surface-sensitive X-ray Absorption Spectroscopy (XAS) measurements provided insights into the cation distributions at the surfaces, showing significant deviations from bulk properties, particularly in ZnFe2O4 in which 52% of the near-surface tetrahedral sites are occupied by Fe cations, compared to 26% in the bulk. DFT simulations of ZnFe2O4 illustrated how the surface terminations can alter the thermodynamic preference for cation distribution in comparison with the bulk. Our findings illustrate the complex interplay between surface and bulk properties in spinel ferrites.
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Sep 2024
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B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
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F.
Bassato
,
S.
Mauri
,
L.
Braglia
,
A. Yu.
Petrov
,
E.
Dobovičnik
,
F.
Tavani
,
A.
Tofoni
,
P.
Ferrer
,
D.
Grinter
,
G.
Held
,
P.
D'Angelo
,
P.
Torelli
Diamond Proposal Number(s):
[33111]
Abstract: A-site doped SrTiO3 is considered as a promising substitute for traditional anodic metals in solid oxide fuel cells (SOFCs). In this study, we present the reactivity of La0.2Sr0.25Ca0.45TiO3 (LCSTO), La0.2Sr0.7TiO3 (LSTO), and SrTiO3 (STO) toward H2 by operando ambient pressure NEXAFS spectroscopy and theoretical spectra simulation with FDMNES code. The samples were synthesized by MBE (molecular beam epitaxy), hydrothermal, and modified-Pechini routes. We found that the reducibility of the samples depends not only on their stoichiometry but also on the morphology, which is determined by the synthetic method. The results of these experiments give insight into the reducibility of Ti4+ in perovskites as well as the opportunity to further optimize the synthesis of these materials to obtain the best performance for SOFC applications.
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Aug 2024
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B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
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Frances K.
Towers Tompkins
,
Lewis G.
Parker
,
Richard M.
Fogarty
,
Jake M.
Seymour
,
Ekaterina
Gousseva
,
David C.
Grinter
,
Robert G.
Palgrave
,
Christopher D.
Smith
,
Roger A.
Bennett
,
Richard P.
Matthews
,
Kevin R. J.
Lovelock
Diamond Proposal Number(s):
[29413, 30367, 31939, 33378, 35207]
Open Access
Abstract: X-ray photoelectron spectroscopy (XPS) and ab initio calculations show that fully alkylated onium cation electronic structure can be tuned using both the alkyl chains and the central onium atom. The key for tuning the central onium atom is methyl versus longer alkyl chains, allowing selection of the optimum cation for a wide range of applications, including catalysis and biocides.
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Aug 2024
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