The objective of the QWellMagNa project is to study magnetic nanostructures embedded in metallic matrixes. The originality of the project is twofold: on one hand it is based on the use of spectroscopic properties of quantum wells (QW) formed between the magnetic particles and the surface, on the other hand it relies on an ambitious experimental approach using scanning tunnel microscopy with functionalized active microfabricated tips. The nanoparticles buried a few nanometers below the surface confine the electrons between their magnetic interface and the surface of the matrix forming quasi-open QW. QW will be detected by scanning tunneling microscopy / spectroscopy (STM / STS) with active planar magnetic probes. The spectroscopic properties of QW reflects the position and the depth of the nanoparticles but also their shape and their magnetic state. The detailed analysis of the spatial variation at the surface of the electron density will therefore make possible to extract this information. The original use of "tip-on-chip" active planar probes allows us to locally generate the magnetic fields necessary both for the magnetic detection (modulation) and for the magnetic manipulation of nanoparticles. This field will be generated by current pulses flowing across an special structure on the STM tip specifically designed for this purpose. The probes developed within the framework of this project will be manufactured by standard lithography processes and could be adaptable to any tunnel microscopy equipment, thus broadening the area of application of the STM. We will also work on the individual manipulation of the magnetic state of an individual nanoparticle in an assembly which offers unique perspectives for studying the effects of magnetization dynamics of correlated systems with QW states.

Emerging MOFs super-adsorbents present advantageous adsorption capacities, up to 60% higher than those of conventional activated carbons or zeolites. Consequently, for the two worldwide major issues of industry decarbonation and energy transition, those materials offer great perspectives such as CO2 capture and energetic gas (H2, CH4, NG) storage. Nevertheless, those enhanced storage capacities are related to equally important inhibiting thermal effects (exothermic under adsorption, endothermic under desorption). At industrial scale, those thermal effects would induce major reduction in performances (capacity, selectivity and charge/discharge kinetics) even hazard issues (hot spots). Up to date, whereas the literature on MOF for gas storage or capture is plethoric, only few research efforts were devoted to the thermal management of MOF. The project is fully devoted to it, gathering a complementary consortium of partner experts on the various multidisciplinary aspects from MOF elaboration to the targeted applications. We will especially focus our work on the development of MOF/graphite conducting composites, which will for example be of interest for isothermal-diabatic applications such as CO2 cpture in TSA processes. The 4 years research effort is shared between MOF and related composites elaborations and characterizations, comparison between raw MOF and composites, assessments of applications related performances, multi-scale modelisations (from composite material to industrial process) and lab-scale pilot tests. For all steps, from academic research to industrial concerns, environmental impacts are continuously considered.

The first objective of the project is to understand what controls cavitation, i.e. the formation of bubbles in a metastable liquid, when this liquid is confined in cavities with dimensions of the same order as the size of the critical germ of nucleation. Classically, the nucleation rate follows an Arrhenius law involving a barrier energy and a kinetic prefactor that depends on the dynamics of the critical germ. Both parameters are likely to be modified by confinement, but only the effect on the barrier has been studied theoretically. Current experimental data are limited and do not allow distinguishing between effects on the barrier from those on the prefactor. The second objective is to study cavitation in superfluid helium, a model system for homogeneous nucleation. Recent acoustic cavitation experiments suggest that nucleation takes place on vortices. Measuring nucleation in cavities and under quasi-static conditions would settle the debate. The first key to understand the effects of confinement is to synthesize pores of controlled size of the order of 10 nm, connected to the fluid reservoir by small openings, also of controlled size. We will explore several cases: porous alumina, ordered porous silica and nanolithography. For each, we can also vary the confinement by varying the size of the critical germ via the temperature of the fluid (nitrogen and argon). The precise measurement of the nucleation rate by a new capacitive technique should make it possible to distinguish the effects on the barrier from those on the kinetic prefactor. The second key is to interpret these measurements thanks to precise numerical calculations based, on the one hand, on new methods to evaluate the energy barriers, and on the other hand, on a study by molecular dynamics of the impact of pore geometry on nucleation rate.

The MIGRASENS ANR’s objective is to develop a new generation of water pollutants microsensors network based on the association of CVD graphene and Molecular Imprinted Polymer (MIP). By coupling the properties of the graphene in terms of conduction, robustness, electrochemical sensitivity and the MIP selectivity, the consortium wants to design a lab-on-chip for the detection of a wide scope of micropollutants highlighted in the Water Frameworks Directive. The ambition of this project is to go to the CVD graphene production to its integration in a multidetection lab-on-chip prototype. The success of the project relies on the complementary competencies of the consortium, which includes two societies DSA technologies (Orléans) and Annealsys (Montpellier) and two academic laboratories ICMN (Orléans) and L2C (Montpellier), will allow to have got an overall point of view. The main scientific challenge will be to optimize the electro activity of the graphene electrode by the control of the growth parameters of CVD graphene and to use it as conductive platform of the sensor.

Cavitation, i.e. the formation of a vapor bubble in a stretched liquid, is of fundamental interest and plays a central role in many technologies and natural science. For decades, the consensus has been that, in bulk liquid, cavitation occurs via the stochastic formation of a bubble nucleus as described by the Classical Nucleation Theory (CNT). Whether the same could also happen in liquid confined inside a nanopore has only been recently considered. A few experiments, some of them performed by members of the consortium, suggest that liquids in nanoporous materials can indeed evaporate through cavitation. However, results are scarce, contradictory and no coherent picture has yet emerged. In this project, the main issue is to elucidate if and how cavitation occurs in nanopores: what is the influence of fluid-wall interaction, of the temperature? Is nucleation homogeneous or heterogeneous? To this aim, we propose to explore the behavior of different fluids at variable temperatures in tailored nanomaterials with pores having a so-called ink-bottle geometry. Another issue, and a pre-requisite for the study of confined cavitation, is to test accurately the relevance of the CNT to bulk, homogeneous, cavitation. To shed light on current issues in the field, we propose to use simple liquids (helium, nitrogen, and argon) as benchmark to perform bulk cavitation experiments using the so-called 'synthetic tree' developed at Cornell University. The last issue concerns very small closed systems: it was recently predicted that the constraint of mass conservation could inhibit cavitation and lead to a superstabilization of a stretched liquid. We will carry out the first experimental study of this phenomenon to confirm, or rule out, its existence. Our ambitious project is based on the complementary expertise from four laboratories : Institut Néel (NEEL), Institut des NanoSciences de Paris (INSP), Laboratoire de Physique Statistique de l'Ecole Normale Supérieure (LPSENS), and Interfaces, Confinement, Matériaux et Nanostructures, (ICMN). It gathers a unique ensemble of skills and know-how with several original features and challenges. A first one is to use a large variety of fluids, going from simple cryogenic liquids (helium, argon, nitrogen) to more complex room temperature liquids (alkanes and water). Helium, a perfectly wetting fluid, will be a benchmark for purely homogeneous cavitation. Comparison with the other fluids will reveal the influence of the fluid structure and the nature of the fluid-wall interaction on cavitation. A second original feature is to use cryogenic liquids up to their critical temperature, giving access to the region where cavitation is expected to be the mechanism of evaporation in porous materials. A third one is to master the elaboration of porous silicon and porous alumina membranes with a controlled ink-bottle geometry allowing unambiguous detection of cavitation. A fourth original feature is the joint approach coupling experiments and theoretical analysis, based on either a generalization of the CNT to a confined geometry or direct molecular simulations. These theoretical approaches will be compared together, and will help to rationalize our experimental results. By exploring a large range of physical parameters such as the liquid-vapor surface energy or the fluid-wall interactions, together with the expected progresses in its theoretical numerical modeling, our project will bring unprecedented experimental information on cavitation, both in bulk and confined geometries. Beyond their expected large impact in the adsorption community, our results will be relevant for other fields of physics such as statistical or soft matter physics. They may also have implications in interdisciplinary fields such as geophysics or biophysics.