A stereo approach to elucidating complex fluids at the nanoscale with Neutrons and X-rays
ILL50-110
ILL50
Understanding the microstructure of complex fluids across multiple scales is essential for building predictive models. While Small Angle Scattering - using neutrons at ILL or X-rays at ESRF - provides invaluable data, fitting individual scattering profiles that have often few features may yields numerical outputs rather than deep physical insights. A paradigm shift occurs when integrating complementary techniques: By combining SAXS, SANS, static and dynamic light scattering with Molecular Dynamics or random Gaussian wavelets simulations, researchers can achieve robust, quantitative analyses—especially when thermodynamic principles, such as those evoked by Maxwell's demon, are incorporated.
This symposium will explore advanced methodologies that bridge scattering techniques with enthalpic and entropic considerations, enabling the development of practical modeling strategies. We will highlight breakthroughs in critical applications, from innovative recycling separation processes to the design of biomimetic colloids with antiviral potential.
Biliquid foam structure can be observed by neutrons, X-rays and light. Thermal fluctuations controlling the stability are symbolised by the hand of a Maxwell's daemon.
The workshop will also include a special session to honor the career and contributions of Thomas Zemb, a pioneer in the field of colloids and their application in recycling and green processes, as he is moving to an emeritus status 53 years after his first publication with Francis Perrin. In the late 70s, Thomas was building a high sensitivity lab-SAXS as well as a high-resolution USAXS at CEA/Saclay with the help of André Guinier, the father of small-angle X-ray scattering. Later he joined ILL for a year as a technician where he participated in the first experiments on interacting charged surfactant micelles analyzed in absolute scale with both SANS (D11, D17) and SAXS under the supervision of John B Hayter, with Luc Belloni establishing theoretical expressions. In the early 90s, he together with Joan Bordas and Heinrich Stuhrmann advocated for the selection of ID01 and ID02 beamlines at the ESRF. With Peter Lindner, he co-founded the Bombannes summer schools. As the founding director of the Institut de Chimie Séparative de Marcoule (ICSM), he advanced the characterization of colloidal systems through modern colloid science, enhancing separation processes fundamental to hydrometallurgy. His former students and post-docs have used the stereoscopic approach combining X-ray, neutron and light scattering with thermodynamics and simulations. This has led to key progresses in physics, chemistry, biophysics and technology, that will be discussed in this workshop.
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Combining modalities enables revealing the complexity of matter. After having learnt this lesson from Thomas Zemb while studying colloidal systems with him in the years 2000, i later applied it to completely different fields of research – the latter being the operando investigation of battery materials. In this talk i will emphasize the advantages and necessity of SAXS/SANS techniques coupled to other tools as electrochemical methods, neutron/x-ray imaging, or spectroscopic techniques, to visualize and quantify nanoscale changes that happen in electrolyte and electrode materials during device cycling, and their link to the battery performance and longevity. Nanostructured materials as single-ion conducting polymers, nanoengineered silicon-based negative electrodes or hard carbon composites, are key components of emerging technologies for better, safer and more sustainable Li-ion and Na-ion batteries. Synchrotron methods as fast scanning SAXS and SAXS-computed tomography techniques [1] are needed to uncover the extended spatiotemporal spaces where multiple reaction and degradation phenomena that happen in a working battery.
Figure 1. 3D imaging of the interior of a battery using SAXS-CT, enabling to reveal specific defects and areas not lithiating correctly due to active material aggregation [1].[1] E. Lübke et al, Energy Environ. Sci. 17, 5048-5059 (2024)
Speaker: Sandrine Lyonnard (CEA-IRIG) -
The literature indicates that the water surface is negative even at bulk pH well below 7. Our instrument excites, and is able to detect, the capillary modes of macroscopic bubbles with oscillations of minimal amplitude. The surface undulations are amplified at resonance by e.m. waves of 0.2 - 20 V/cm, reaching figures in the range of 0.5-20 nm ($10^{-6}$ times the bubble size). The bubble response originates from the interference of the two beams reflected from the opposite bubble interfaces when an incoming laser beam crosses its diameter. The amplitude of capillary oscillations depends on the bubble’s effective charge at nanometric distances from the surface. Effective charge sign is detected by the Cross spectrum between exciting e.m. field and interferometric response (Figure 1). Outcomes are a) in-phase response maintained from neat water to negative SDS coated bubbles, b) null response seen when the right number of positive DTAB molecules adsorb on a bare bubble, c) basic solutions show in-phase response of increasing amplitude when bulk pH increases and d) acidic bulk solutions show in-phase response down to bulk pH < 3, where it changes to out-of-phase response due to effective charge sign changed from negative to positive.
Figure 1. Cross spectrum between exciting e.m. field and interferometric signal (blue) for the first resonance of the capillary mode (black).Speaker: Paola Brocca (Università degli Studi di Milano)
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Bimetallic Janus nanocrystals result from integrating two distinct metals side-by-side into one single particle[1]. This asymmetric arrangement allows the unique properties associated with each metal to be incorporated in tandem. When dispersed in an appropriate catalytic medium, such particles exhibit self-propulsion mediated by diffusiophoresis[2,3]. Before these properties can be exploited, robust and scalable synthesis protocols are required. Here we demonstrate the preparation of bimetallic palladium-silver Janus nanocrystals using a seed-mediated growth method[4]. The kinetically controlled overgrowth of plasmonic Ag caps on the Pd seeds is followed by coupling in-situ small-angle X-ray scattering (SAXS) with UV-Vis absorption spectroscopy. Currently these self-propelled systems are typically studied at low volume fractions. Moving forward with a robust synthesis and sufficient yield of these particles, it will be possible to realize self-propelled or active colloids at high volume fractions. SAXS and X-ray photon correlation spectroscopy (XPCS) will be used to probe the interactions and dynamics in these active systems. Furthermore, the asymmetry of particles enables to access the rotational diffusion by XPCS. This work provides a groundwork for future studies into the diffusiophoretic self-propulsion of active colloids, which mimic certain collective behavior of living systems.
Figure 1. Schematic illustration of Pd-Ag growth through controlled injection rate (left). In-situ SAXS patterns of palladium seed growth (right).References
[1] Qiu J. et al. Bimetallic Janus Nanocrystals: Syntheses and Applications. Adv. Mater. 2022, 34, 2102591.
[2] Zinn T. et al. Emergent dynamics of light-induced active colloids probed by XPCS. New J. Phys. 2022, 24, 093007.
[3] Zhu W. et al. Exploring the Synthesis of Self-Organization and Active Motion. J. Phys. Chem. Lett. 2024, 15 (20), 5476-5487.
[4] Zeng, J. et al. Controlling the Nucleation and Growth of Silver on Palladium Nanocubes by Manipulating the Reaction Kinetics. Angew. Chem. Int. Ed. 2012. 51: 2354-2358.Speaker: Austin Hubley (ESRF)
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