Disordered metasurfaces provide a versatile platform for harnessing near- and far-field scattered light. Most research has focused on either particulate topologies composed of individual, well-identified metaatoms or, to a lesser extent, semi-continuous aggregate topologies without well identified inclusions. Here, we uncover an intermediate critical packing regime characterized by metasurface morphologies in which a significant fraction of metaatoms begin to connect. We experimentally demonstrate that, at this threshold, the properties of the scattered light abruptly change and, via a statistical quasinormal mode analysis, interpret this change as a marked transition in the statistics of the photon density of states. Unlike percolation in semicontinuous metal films, this transition affects not only the specular but also the diffuse components of the scattered light in a profound way. Our results introduce critical packing topologies as a novel design strategy for manipulating the spectral and angular characteristics of light using ultrathin optical coatings. Emergent functionalities include colour shifts in diffuse light driven by multiple scattering and surface whitening, with potential applications in display technologies, for example, to reduce glare in electronic screens.

With the increasing miniaturization of electronic components and the need to optimize thermal management, it has become essential to understand heat transport at metal/semiconductor interfaces. While it has been recognized decades ago that an electron phonon channel may take place at metal-semiconductor interfaces, its existence is still controversial. Here, we investigate thermal transport at metal-silicon interfaces using the combination of first principles calculations and nonequilibrium Green's function (NEGF). We explain how to correct NEGF formalism to account for the out of equilibrium nature of the energy carriers in the vicinity of the interface. The relative corrections to the equilibrium distribution are shown to arise from the spectral mean free paths of silicon and may reach 15 percents. Applying these corrections, we compare the predictions of NEGF to available experimental data for Au/Si, Pt/Si and Al/Si interfaces. Based on this comparison, we infer the value of the electron phonon interfacial thermal conductance by employing the two temperature model. We find that interfacial thermal transport at Au/Si interfaces is mainly driven by phonon phonon processes, and that electron phonon processes play a negligible role in this case. By contrast, for Al/Si interfaces, we show that phonon-phonon scattering alone can not explain the experimental values reported so far, and we estimate that the electron-phonon interfacial conductance accounts for one third of the total conductance. This work demonstrates the importance of the electron-phonon conductance at metal-silicon interfaces and calls for systematic experimental investigation of thermal transport at these interfaces at low temperatures. It paves the way for an accurate model to predict the conductance associated to the interfacial electron phonon channel.

Understanding the adsorption of water and characterizing the water film formed within nanostructures are essential for advancements in fields such as nanofluidics, water purification, and biosensing devices. In our research, we focus on studying the condensation and transport of water through an alumina membrane with nanopores of varying wettabilities. We introduce a method to alter the membrane's wettability and enhance dissociative adsorption by varying the duration of exposure during plasma cleaning. To create different experimental environments, we modify humidity levels by controlling vapor pressure. To investigate water transport within the membrane, we apply a voltage and analyze the resulting current response. Our analysis indicates that transport properties improve with thicker water films. We use the Polanyi theory of adsorption to capture the physics of the problem. Analyzing the conductance inside the nanopores, we find that the first monolayers may stagnate due to interactions with the pore walls. This research significantly enhances our understanding of vapor condensation within nanomaterials, particularly considering the influence of different wettabilities. These findings have broad implications for applications such as water vapor capture and related technologies.

Natural rubber is obtained by processing natural rubber latex, a liquid colloidal suspension that rapidly gels after exudation from the tree. We prepared such gels by acidification, in a large range of particle volume fractions, and investigated their rheological properties. We show that natural rubber latex gels exhibit a unique behavior of irreversible strain hardening: when subjected to a large enough strain, the elastic modulus increases irreversibly. Hardening proceeds over a large range of deformations in such a way that the material maintains an elastic modulus close to, or slightly higher than the imposed shear stress. Local displacements inside the gel are investigated by ultrasound imaging coupled to oscillatory rheometry, together with a Fourier decomposition of the oscillatory response of the material during hardening. Our observations suggest that hardening is associated with irreversible local rearrangements of the fractal structure, which occur homogeneously throughout the sample.

Active fluids made of powered suspended particles have unique abilities to self-generate flow and density structures. How such dynamics can be triggered and leveraged by external cues is a key question of both biological and applied relevance. Here we use magnetotactic bacteria to explore how chemotaxis and magnetotaxis -- leading, respectively, to positional and orientational responses -- combine to generate global scale flows. Such steady regime can be quantitatively captured by a magneto-active hydrodynamic model, while time-dependent magnetic driving unveils additional patterning complexity. Overall, our findings shed light on how active fluids respond to the ubiquitous situation of multiple external information, also suggesting routes for their manipulation.

Scintillation at cryogenic temperatures can give rise to detectors with particle discrimination for rare-event searches such as dark matter detection. We present time-resolved scintillation studies of Caesium Iodide (CsI) under excitation of both alpha and gamma particles over a long acquisition window of 1 ms to fully capture the scintillation decay between room temperature and 4 K. This allows a measurement of the light yield independent of any shaping time of the pulse. We find the light yield of CsI to increase up to two orders of magnitude from that of room temperature at cryogenic temperatures, and the quenching factor of alpha to gamma excitation to exceed 1 over a range of temperatures between 10 and 100 K. We also find the time structure of the emitted light to follow similar exponential decay time constants between alpha and gamma excitation, with the temperature behaviour consistent with a model of self-trapped exciton de-excitation.

The separation of colloidal particles based solely on their surface properties is a highly challenging task. This study demonstrates that diffusiophoresis and diffusioosmosis enable the continuous separation of carboxylate polystyrene particles with similar sizes and zeta potentials but distinct surface concentrations of carboxyl groups. The particles are exposed to salt concentration gradients generated in a double-junction microfluidic device. Through experimental and theoretical analyses, we demonstrate how the particle dynamics are influenced by their zeta potential sensitivity to the local salt concentration, which in turn is affected by surface conductance effects induced by the surface carboxyl groups. Consequently, colloids with comparable zeta potentials but differing surface concentrations of carboxyl groups can be separated with 100% efficiency. This approach, which employs a simple, easy-to-operate device, has discipline-spanning potential for the continuous separation of colloids distinguished solely by surface properties that influence their zeta potential sensitivities, like roughness, permeability, heterogeneity, and chemical composition.

Molecular dynamics simulations of aqueous electrolytes generally rely on empirical force fields, combining dispersion interactions - described by a truncated Lennard-Jones (LJ) potential - and electrostatic interactions - described by a Coulomb potential computed with a long-range solver. Recently, force fields using rescaled ionic charges (electronic continuum correction, ECC), possibly complemented with rescaling of LJ parameters (electronic continuum correction rescaled, ECCR), have shown promising results in bulk, but their performance at interfaces has been less explored. Here we started by exploring the impact of the LJ potential truncation on the surface tension of a sodium chloride aqueous solution. We show a discrepancy between the numerical predictions for truncated LJ interactions with a large cutoff and for untruncated LJ interactions computed with a long-range solver, which can bias comparison of force field predictions with experiments. Using a long-range solver for LJ interactions, we then show that an ionic charge rescaling factor chosen to correct long-range electrostatic interactions in bulk also describes accurately image charge repulsion at the liquid-vapor interface, and that the rescaling of LJ parameters in ECCR models - aimed at capturing local ion-ion and ion-water interactions in bulk - also describes well the formation of an ionic double layer at the liquid-vapor interface. Overall, these results suggest that the molecular modeling of aqueous electrolytes at interfaces would benefit from using long-range solvers for dispersion forces, and from using ECCR models, where the charge rescaling factor should be chosen to correct long-range electrostatic interactions.

Brownian thermal noise of thin-film coatings is a fundamental limit for high-precision experiments based on optical resonators such as gravitational-wave interferometers. Here we present the results of a research activity aiming to develop lower-noise ion-beam sputtered silicon nitride thin films compliant with the very stringent requirements on optical loss of gravitational-wave interferometers. In order to test the hypothesis of a correlation between the synthesis conditions of the films and their elemental composition and optical and mechanical properties, we varied the voltage, current intensity and composition of the sputtering ion beam, and we performed a broad campaign of characterizations. While the refractive index was found to monotonically depend on the beam voltage and linearly vary with the N/Si ratio, the optical absorption appeared to be strongly sensitive to other factors, as yet unidentified. However, by systematically varying the deposition parameters, an optimal working point was found. Thus we show that the loss angle and extinction coefficient of our thin films can be as low as $(1.0 \pm 0.1) \times 10^{-4}$rad at$\sim$2.8 kHz and$(6.4 \pm 0.2) \times 10^{-6}$ at 1064 nm, respectively, after thermal treatment at 900 $^{\circ}$C. To the best of our knowledge, such loss angle value is the lowest ever measured on this class of thin films. We then used our silicon nitride thin films to design and produce a multi-material mirror coating showing a thermal noise amplitude of $(10.3 \pm 0.2) \times 10^{-18}$m Hz$^{-1/2}$ at 100 Hz, which is 25\% lower than in current mirror coatings of the Advanced LIGO and Advanced Virgo interferometers, and an optical absorption as low as $(1.6 \pm 0.5)$ parts per million at 1064 nm.

Most organic and inorganic surfaces (e.g., glass, nucleic acids or lipid membranes) become charged in aqueous solutions. The resulting ionic distribution induces effective interactions between the charged surfaces. Stacks of like-charged lipid bilayers immersed in multivalent ion solutions exhibit strong coupling (SC) effects, where ion correlations cause counter-intuitive membrane attraction. A similar attraction observed with monovalent ions is explained by SC theory through reduced dielectric permittivity under confinement. To explore this phenomenon, we propose a modified Poisson-Boltzmann (mPB) model with spatially varying dielectric permittivity and explicit Born solvation energy for ions. We use the model to investigate the dielectric permittivity profile of confined water in molecular dynamics simulations of charged lipid layers stacks at varying hydration levels, and compare the results with alternative computational methods. The model captures a sharp decrease in permittivity as the system enters the attractive regime, converging to a plateau value that we attribute to lipid headgroups. The generic nature of the mPB framework allows application to other systems, such as other biological interfaces or solid walls, provided ions follow Boltzmann statistics.

Core-shell nanoparticles, particularly those having a gold core, have emerged as a highly promising class of materials due to their unique optical and thermal properties, which underpin a wide range of applications in photothermal therapy, imaging, and biosensing. In this study, we present a comprehensive study of the thermal dynamics of gold-core silica-shell nanoparticles immersed in water under pulse illumination. The plasmonic response of the core-shell nanoparticle is described by incorporating Mie theory with electronic temperature corrections to the refractive indices of gold, based on a Drude Lorentz formulation. The thermal response of the core-shell nanoparticles is modeled by coupling the two temperature model with molecular dynamics simulations, providing an atomistic description of nanoscale heat transfer. We investigate nanoparticles with both dense and porous silica shells (with 50% porosity) under laser pulse durations of 100 fs, 10 ps, and 1 ns, and over a range of fluences between 0.05 and 5mJ/cm2. We show that nanoparticles with a thin dense silica shell (5 nm) exhibit significantly faster water heating compared to bare gold nanoparticles. This behavior is attributed to enhanced electron-phonon coupling at the gold silica interface and to the relatively high thermal conductance between silica and water. These findings provide new insights into optimizing nanoparticle design for efficient photothermal applications and establish a robust framework for understanding energy transfer mechanisms in heterogeneous metal dielectric nanostructures.

We present a modular user-oriented simulation toolbox for studying highharmonic generation in gases. The first release consists of the computational pipeline to 1) compute the unidirectional IR-pulse propagation incylindrical symmetry, 2) solve the microscopic responses in the whole macroscopic volume using a 1D-TDSE solver, 3) obtain the far-field harmonic field using a diffraction-integral approach. The code comes with interfaces and tutorials, based on practical laboratory conditions, to facilitate the usage and deployment of the code both locally and in HPC-clusters. Additionally, the modules are designed to work as stand-alone applications as well, e.g., 1D-TDSE is available through Pythonic interface.

Densified SiO2 glasses, obtained from different pressure and temperature routes have been annealed over a wide range of temperature far below the glass transition temperature (500$^\circ$C-900$^\circ$C). Hot and cold compressions were useful to separate the effects of pressure and the compression temperature. In-situ micro-Raman spectroscopy was used to follow the structural evolution during the thermal relaxation. A similar glass structure between the non-densified silica and the recovered densified silica after the temperature annealing demonstrates a perfect recovery of the non-densified silica glass structure. While the density decreases monotonically, the structural relaxation takes place through a more complex mechanism, which shows that density is not a sufficient parameter to fully characterize the structure of densified silica glass. The relaxation takes place through a transitory state, consisting in an increase of the network inhomogeneity, shown by an increase in intensity of the D2 band which is associated with 3 membered rings. The activation energy of these processes is 255$\pm$45 kJ/mol for the hot compressed samples. The kinetic is overall faster for the cold compressed samples. In that last case the relaxation is partially activated by internal stresses release.

The next generation of gravitational-wave detectors, such as the Einstein Telescope, is designed to reduce noise in a wide band of frequencies compared to the current generation, through the use of new technologies. ETpathfinder, designed as an R&D facility for these technologies, is a prototype for which the mirrors were chosen to be made of crystalline silicon, produced by the Leibniz-Institut für Kristallzüchtung. This material choice was made to pave the way for a low thermal noise level at cryogenic temperatures in the Einstein Telescope. This paper shows the mechanical loss of silicon designated to become the test masses for ETpathfinder in the range between room temperature and 53K. In addition, the effect of the anisotropic nature of silicon on the measurement procedure is addressed. Predictions are made of the contribution of the mirror substrate material to the overall ETpathfinder noise budget.

Generation of ultra high frequency acoustic waves in water is key to nano resolution sensing, acoustic imaging and theranostics. In this context water immersed carbon nanotubes (CNTs) may act as an ideal optoacoustic source, due to their nanometric radial dimensions, peculiar thermal properties and broad band optical absorption. The generation mechanism of acoustic waves in water, upon excitation of both a single-wall (SW) and a multi-wall (MW) CNT with laser pulses of temporal width ranging from 5 ns down to ps, is theoretically investigated via a multi-scale approach. We show that, depending on the combination of CNT size and laser pulse duration, the CNT can act as a thermophone or a mechanophone. As a thermophone, the CNT acts as a nanoheater for the surrounding water, which, upon thermal expansion, launches the pressure wave. As a mechanophone, the CNT acts as a nanopiston, its thermal expansion directly triggering the pressure wave in water. Activation of the mechanophone effect is sought to trigger few nanometers wavelength sound waves in water, matching the CNT acoustic frequencies. This is at variance with respect to the commonly addressed case of water-immersed single metallic nano-objects excited with ns laser pulses, where only the thermophone effect significantly contributes. The present findings might be of impact in fields ranging from nanoscale non-destructive testing to water dynamics at the meso- to nano-scale.

The existence of multiple amorphous states, or polyamorphism, remains one of the most debated phenomena in disordered matter, particularly regarding its microscopic origin and impact on glassy dynamics. Profiting of the enhanced data quality provided by brilliant synchrotrons, we combined high pressure X-ray photon correlation spectroscopy and X-ray diffraction to investigate the atomic dynamics-structure relationship in a Au49Cu26.9Si16.3Ag5.5Pd2.3 metallic glass at room temperature. We identify a structural and dynamical crossover near 3 GPa, marked by avalanches-like massive atomic rearrangements that promote the system toward increasingly compact atomic cluster connections. This crossover superimposes to a pressure-induced acceleration of the atomic motion recently reported, and signals the onset of a transitional state, potentially linked to the nucleation of a new phase within the glass, characterized by the coexistence of two amorphous states with distinct relaxation processes. These results provide evidence for a sluggish, continuous polyamorphic transformation, even in absence of marked structural discontinuities.

In this paper, we propose a new derivation for the Green-Kubo relationship for the liquid-solid friction coefficient, characterizing hydrodynamic slippage at a wall. It is based on a general Langevin approach for the fluctuating wall velocity, involving a non-markovian memory kernel with vanishing time integral. The calculation highlights some subtleties of the wall-liquid dynamics, leading to superdiffusive motion of the fluctuating wall position.

Friction is one of the main sources of dissipation at liquid water/solid interfaces. Despite recent progress, a detailed understanding of water/solid friction in connection with the structure and energetics of the solid surface is lacking. Here we show for the first time that \textit{ab initio} molecular dynamics can be used to unravel the connection between the structure of nanoscale water and friction for liquid water in contact with graphene and with hexagonal boron nitride. We find that whilst the interface presents a very similar structure between the two sheets, the friction coefficient on boron nitride is $\approx 3$ times larger than that on graphene. This comes about because of the greater corrugation of the energy landscape on boron nitride arising from specific electronic structure effects. We discuss how a subtle dependence of the friction on the atomistic details of a surface, that is not related to its wetting properties, may have a significant impact on the transport of water at the nanoscale, with implications for the development of membranes for desalination and for osmotic power harvesting.

This work presents the implementation of a new charge detection mass spectrometer (CDMS) design that operates in a stand-alone mode, thanks to its integration with nanoelectrospray ionization. More specifically, this innovative CDMS consists of a linear charge detection array ion trap spectrometer that combines an eight-tube detector array with conical electrodes. This configuration allows for recording data in both transmission mode (linear array) and ion trapping mode (ConeArrayTrap), which enables the measurement of time-of-flight (related to the mass-to-charge ratio) along with the charge of individual ions. As a result, this design supports high-throughput metrology of viruses at the single-particle level. The devices and geometry of the instrument have been developed based on ion optics simulations. The performance of the current instrument is demonstrated using human norovirus-like particles (hNoVLP) and Adenovirus Ad(5) (hAdV5).

The OSQAR photon regeneration experiment searches for pseudoscalar and scalar axion-like particles by the method of "Light Shining Through a Wall", based on the assumption that these weakly interacting sub-eV particles couple to two photons to give rise to quantum oscillations with optical photons in strong magnetic field. No excess of events has been observed, which constrains the di-photon coupling strength of both pseudoscalar and scalar particles down to $5.7 \cdot 10^{-8}$ GeV$^{-1}$ in the massless limit. This result is the most stringent constraint on the di-photon coupling strength ever achieved in laboratory experiments.