Category: SOLEIL

Optimization of 2D material-based devices

Optimization of 2D material-based devices

How to visualize electric fields in situ to boost the performance of tomorrow’s LEDs

2D materials are excellent candidates for light emission in LED-type components. Furthermore, combining several of these materials with different properties (metal, insulator, semiconductor) theoretically makes it possible to obtain complex components that combine these properties. To function, these components must be connected to electrodes. But where exactly should the electrical voltage be applied? 
To answer this question, a team from the Paris Institute of NanoSciences used the ANTARES beamline to probe operando the distribution of the electric field within a heterostructure composed of two semiconductors.

Two-dimensional (2D) materials, such as transition metal dichalcogenides (TMDs) (e.g., MoS₂, WSe₂, and their derivatives), exhibit strongly enhanced excitonic effects due to the robust Coulomb coupling between electron-hole pairs. This makes them outstanding candidates for light emission in devices such as LEDs. A second key advantage of this materials platform is the ability to assemble these materials without epitaxial constraints. In theory, this allows for the combination of materials with diverse properties—metals, insulators, and semiconductors with tunable bandgaps—to fabricate complex devices. The entire structure is ultimately connected to electrodes, which serve to inject charges or modulate the potential profile. However, a critical challenge remains: the voltage must be applied in the right location! In these structures, the energy landscape is influenced by edge effects, doping, flake thickness, defects, and above all interfaces. In this study, a team from INSP uses the ANTARES beamline to operando probe the electric field distribution within a heterostructure composed of two semiconductors.

In optoelectronic devices, electrodes are used to inject the current/energy necessary for device operation. In the context of LEDs, applying a bias is essential to inject holes into the valence band while electrons are resonantly injected into the conduction band. When these energy conservation rules are fulfilled, charges can be injected into the optically active semiconductor, enabling light emission. However, the turn-on voltage for an LED can be significantly larger than the material’s bandgap if an electric field is also applied to the intermediate material between the electrode and the optically active layer. This results in power efficiency losses, which must be mitigated. Therefore, the localization of the electric field is critical, and tools to measure the field distribution operando are essential.

Read more on the SOLEIL website

The study of Gallo-Roman curse tablets discovered in Orléans continues at the PSICHÉ beamline

The study of Gallo-Roman curse tablets discovered in Orléans continues at the PSICHÉ beamline

After conducting a first series of highly conclusive test measurements in October 2024 on the PSICHE beamline, two archaeologists from the Archaeology Department of the City of Orléans returned in December 2025 with the aim of accessing the texts inscribed on 17 Gallo-Roman curse tablets. Their five intense days of X-ray microtomography on PSICHE have already yielded a wealth of results.

In Orléans, as part of the redevelopment of the former Porte Madeleine hospital, a previously unknown Gallo-Roman necropolis was uncovered thanks to two successive archaeological excavation campaigns carried out between 2022 and 2025. During these excavations, 23 Gallo-Roman lead curse tablets (defixiones, from the Latin defixio, meaning curse or spell) were discovered in the graves, some folded in half, others completely rolled up on themselves.

In order to access the texts engraved on these fragile and precious objects, a few rare tablets were able to be opened, with great expertise and care and following a stabilisation treatment, by a conservator-restorer. However, in most cases, examination of the tablets showed that opening them manually would risk damaging them and, with them, the unique texts they bear.

Yet, using X-ray microtomography, the PSICHÉ beamline team succeeded in 2023 in virtually unrolling a 1,700-year-old lead talisman, revealing an engraved text in the Mandaean language that could then be deciphered.

Read more on the SOLEIL website

Image: At the PSICHÉ beamline workstation, meticulous preparation of the X-ray microtomography scan of a curse tablet

Credit: © SAVO, 2025

Contribution of the HERMES beamline to the study of “Tubenets”

Contribution of the HERMES beamline to the study of “Tubenets”

Network-like structures built by bacteria inside insect cells to feed more efficiently

The cereal weevil, one of the world’s main crop pests, harbors symbiotic bacteria that live inside its cells. Scientists from INRAE and INSA Lyon, in collaboration with experts from the SOLEIL Synchrotron and Claude Bernard University in France, as well as the Max Planck Institute and EMBL in Germany, have discovered that these bacteria build complex, network-shaped membrane structures. These structures increase their surface area for exchange with the host cell, allowing the bacteria to absorb an essential nutrient: sugar.


This is the first time that bacterial structures of this scale have been observed. The SOLEIL’s HERMES beamline contributed to this discovery.

The cereal weevil is one of the major pests affecting cereals such as wheat, rice, and maize, both in the field and in storage. It feeds directly on the grains, but it is not alone: it hosts symbiotic bacteria that live inside its cells. These bacteria, named Sodalis pierantonius, reside in large numbers within specialized insect cells. They provide the weevil with essential nutrients that are absent from its cereal-based diet. This is a mutually beneficial relationship: the bacteria use the sugars produced during the digestion of grains and, in return, supply the insect with essential nutrients such as vitamins and certain amino acids.

While scientists have long understood the importance of this exchange, its exact mechanisms remained unknown. To investigate, the researchers used electron microscopy with an advanced sample preparation method that preserves membranes more effectively. For the first time, the team observed original tubular patterns forming complex membrane structures built by the bacteria. To study the architecture and composition of these structures, the scientists developed new 3D microscopy and analytical methods using the SOLEIL Synchrotron particle accelerator.

Read more on the SOLEIL website

Image: Scale 200 nm. Transmission electron microscopy image showing intracellular symbiotic bacteria from the cereal weevil Sitophilus oryzae. The bacteria form a three-dimensional network of tubular structures, called tubenets. These structures enhance host–bacterium nutritional exchanges, allowing efficient transfer of sugars from the host’s diet to the symbiotic bacteria. In purple, an example of a bacterium and its tubenets can be seen within the cytoplasm of the host cell.

“Research, a collective adventure”

“Research, a collective adventure”

Through a series of portraits, SOLEIL sets out to meet the people who make the synchrotron what it is. For this sixth episode, Edwige Otero, a scientist on DEIMOS—one of SOLEIL’s 29 beamlines—agreed to take part.

Driven from an early age by the joy of understanding, Edwige Otero naturally gravitated toward research. But just as important was her desire to contribute to a collective endeavour, one in which knowledge and discoveries are shared. From Lorraine to Canada, from chemistry to physics, her path reflects a constant passion for science and dialogue.

“Truth be told, I didn’t choose research; I simply followed my interest in science, step by step, and that’s where it led me.” When asked about the origins of her career, Edwige Otero, now a scientist on the DEIMOS beamline at SOLEIL, takes us back to her childhood. “There was no predetermined path, but rather a sensitive, open-minded upbringing and a “sincere and collective investment in the pursuit of knowledge.”

“I was lucky to grow up in a family where reflection and curiosity mattered a lot, where people always took the time to answer our questions,” she explains. “Wondering, asking, and trying to understand became second nature,” she adds. “It’s such an exhilarating feeling when you finally realise: so that’s how it works!”

“All I wanted was to be older”
In the days before the Internet, Edwige learned to look for answers wherever she could: in books, museums, exhibitions, open days… Her first physics–chemistry teacher also played a decisive role: “He made you want to understand everything,” she recalls. “He often took us beyond the official curriculum, and whenever he did, he would say: you’ll learn that later. All I wanted was to be older already.”

Read more on the SOLEIL website

On the shallow surface of isolated nanodiamonds…

On the shallow surface of isolated nanodiamonds…

linkedin sharing button

Nanodiamonds (NDs) are under active investigation for their unique properties and potential applications in energy harvesting, quantum technologies, and nanomedicine. The surface chemistry of diamond nanoparticles strongly modifies their physico-chemical properties (semiconducting behavior, colloidal properties, interaction with water and light). The present study aims to perform a chemical analysis by X-ray photoemission spectroscopy of the ND shallow surface (i. e. the first atomic planes) surrounded with water molecules.
This was achieved on PLEIADES beamline at SOLEIL synchrotron by researchers from NIMBE (CEA-CNRS UMR) on isolated ND in an aerodynamic jet. Results showed for the first time the effect of residual water molecules on different ND surface chemistries.

The electronic properties of diamond nanoparticles (ND) are highly dependent on their surface chemistry (oxidized, hydrogenated). Such ND can be stabilized in water exhibiting different colloidal properties according to their chemistry. These ND colloids can be further used to activate chemical reactions under light: CO2 reduction, hydrogen production, pollutant degradation. The ND / water interface, involved in these reactions, is still under investigation. In this study, the scientists investigated by photoemission the shallow surface chemistry of ND surrounded with water molecules. The synchrotron X-ray beam allowed them to tune the incident photon energy to probe the first atomic layers of ND (here 0.3 nanometer).

Read more on the SOLEIL website

Hydrogen production – a promising electrocatalyst based on clay nanotubes

Hydrogen production – a promising electrocatalyst based on clay nanotubes

Hydrogen is one of the avenues explored to replace fossil fuels. Producing hydrogen by splitting water is a possible pathway, but it requires the use of catalysts that are often made of scarce, expensive materials whose extraction is not environmentally friendly. It is crucial to discover new, cost-effective, noble-metal-free catalysts that still preserve high performance.
A consortium led by researchers from the Laboratoire de Physique des Solides and the Institut de Chimie Physique (CNRS/UPSaclay) has demonstrated the potential of geo-inspired clay nanotubes as sustainable electrocatalysts for the oxygen evolution reaction, the bottleneck in water-splitting processes. Four SOLEIL beamlines contributed to these results.

The oxygen evolution reaction (OER), also known as the water oxidation reaction, 2H₂O ⟶ 4e⁻ + 4H⁺ + O₂, naturally occurs during photosynthesis, which produces the oxygen we breathe. This reaction involves a four-electron transfer, competes with peroxide formation, and requires catalysts to proceed. In recent years, major advances have been achieved with Ir- and Ru-based catalysts, which are considered as benchmark materials for OER. However, despite their high activity and stability, the scarcity and high cost of these elements represent significant limitations for large-scale applications compared with more Earth-abundant elements.

Read more on the SOLEIL website

From soot particles to stardust: Mysteries of their formation revealed by synchrotron light

From soot particles to stardust: Mysteries of their formation revealed by synchrotron light

linkedin sharing button

The formation of soot particles during the incomplete combustion of fuels is both a major environmental challenge on Earth and a model system for understanding the formation of carbon grains in interstellar environments. Yet, the precise mechanism by which these solid particles emerge from gaseous molecules remains one of chemistry’s enduring mysteries.
Thanks to the DESIRS beamline, researchers from PC2A and IPR, in collaboration with the DESIRS-SAPHIRS team, have for the first time directly identified resonance-stabilized radicals involved in the formation of soot particles, shedding new light on this complex process.

Soot particles are formed during the incomplete combustion of hydrocarbon fuels, when the flame lacks sufficient oxygen to fully oxidize carbon. Initially invisible to the naked eye, they gradually form through the aggregation of aromatic molecules before becoming the tiny black grains responsible for a significant share of global air pollution. These particles have a major impact on both human health and climate, contributing to respiratory and cardiovascular diseases and intensifying global warming by absorbing sunlight.

Read more on the SOLEIL website

“Unattended mode” – a new access mode available at SOLEIL for MX

“Unattended mode” – a new access mode available at SOLEIL for MX

Synchrotron SOLEIL is expanding its offering for industry by opening up a new access mode on the PROXIMA-1 and PROXIMA-2A beamlines, dedicated to macromolecular crystallography (MX). 

Companies can now benefit from “Unattended” mode, which offers complete automation of X-ray diffraction data acquisition sessions. 

This mode offers even greater flexibility than Remote access. Simply send us your crystals, programme your experiment and let the instruments perform all the diffraction measurements independently, with no need for on-site or remote supervision, and follow the results on EXI2/ISPyB. 

Read more on the SOLEIL website

Ammonia oxidation – Platinum nanoparticles caught in action

Ammonia oxidation – Platinum nanoparticles caught in action

linkedin sharing button

Ammonia oxidation is a key reaction in the chemical industry, essential for global agriculture and mining, and it also helps limit emissions of this irritating and polluting gas. A SOLEIL team, in collaboration with researchers from CEA-Grenoble, used advanced techniques on the SixS beamline to observe in real time how platinum nanoparticles—used as catalysts for this reaction—deform and change shape during oxidation.
By combining surface diffraction and Bragg coherent diffraction imaging (BCDI), the scientists revealed that the size, shape, and internal strain of the particles directly influence their catalytic efficiency and selectivity. Their results, published in Applied Catalysis B: Environmental, deepen our understanding of this reaction and pave the way for the design of more efficient and durable catalysts, with major implications for both industry and the environment.

The oxidation of ammonia (NH₃) is a vital industrial process for producing nitric oxide (NO), an essential intermediate in the manufacture of nitric acid (HNO₃)—used in fertilizers, explosives, and dyes. However, ammonia oxidation does not produce NO alone; it also generates nitrous oxide (N₂O) and nitrogen gas (N₂). All three products have industrial relevance, and the challenge lies in maximizing the yield of one or the other—this is known as Selective Catalytic Oxidation.
For over a century, platinum (Pt) has been the reference catalyst for NO production. Interestingly, it is used in the form of micrometric wires woven into metallic gauzes rather than as dispersed nanoparticles—one of the last remaining examples of bulk solid catalysts in industrial use. These wires are metallic and polycrystalline, composed of grains similar in size to the particles studied here. Yet, despite more than a hundred years of research, the precise mechanisms by which platinum particles or crystals influence the selectivity and efficiency of the reaction remain only partially understood, particularly under real operating conditions (high temperature, pressure, and gas mixtures).

Read more on the SOLEIL website

Image: Figure 1: Distribution of platinum nanoparticles. Round (blue) and elongated (red) particles display distinct catalytic behaviors.