Master 2 internships
Implementation of functional molecules to map water at the micro-scale in historical oil paint layers
This internship is part of a research program at the PPSM laboratory of the ENS Paris-Saclay, aimed at proposing new fluorescent probes with high spatial and temporal resolution of the complexation - reaction - diffusion phenomena at play in historic paint layers, underlying their alteration. Detailed studies of the mechanisms of metal soaps formation indicate that the role water in these systems [inorganic pigment/organic binder] is crucial. Recent work has shown that the presence of water governs the relative concentration of different coordination states of metal carboxylates and has a major influence on their reactivity. The heterogeneous distribution of water in paint layers because of complex transport mechanisms could explain why certain reaction mechanisms themselves are heterogeneously localized at the microscale.
However, the analytical methods used to probe reactions and chemical structures spatially (synchrotron microbeams, infra-red microscopy) reach their limits when it comes to probing the presence of liquid water in these complex heterogeneous media. In this context, the development of new highly sensitive and selective molecular probes appears particularly interesting for understanding the reactivity and even the alteration of paint layers. This internship proposes to implement functional molecules whose photoluminescence (PL) emissions vary as a function of their solvation.
The student will implement these molecules in model systems representative of pictorial layers and will probe these systems using the PL microscopy instrumentation developed at the PPSM. The aim is to study the PL behaviour of these probes in oil media, and to map the presence of potential aqueous micro-pockets in paint layers.
During the internship, the student will acquire skills from both an analytical and theoretical point of view. On the one hand, he/she will be trained in a wide range of cutting-edge spectroscopic and microscopic techniques. On the other hand, he/she will also acquire knowledge of the chemistry of dynamic phenomena (ionic complexation, diffusion, crystallisation) in heterogeneous media (inorganic pigment + organic binder), and of the links between local microstructure and the physico-chemical mechanisms of reactivity.
Internship period: From January 2024.
Profile required: Student in physico-chemistry with an interest in heritage sciences.