Offre de thèse : Comprehensive study of polymeric materials in ancient paintings by a multimodal analysis (Paris)

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Materials from cultural heritage contain organic substances which have polymerized, which may have suffered from degradation over time, and which are difficult to analyze and understand. Time of- Flight Secondary Ion Mass Spectrometry (TOF-SIMS) imaging and pyrolysis comprehensive twodimensional gas chromatography / mass spectrometry (Py-GCxGC/MS) are two methods which provide, the one a surface analysis at the sub-micrometric scale, but with some identification issues, and the other a complete analysis, but without location. Here we propose to develop a new multimodal analysis associating them. This approach has never been carried out, and their complementarity will allow a better knowledge at the micrometric scale of these fascinating materials.
The object of this thesis project will initially be to use the capabilities of Py-GCxGC/MS to “shed light” on TOF-SIMS analyses of heritage materials, which have now reached a point where questions would otherwise remain unanswered without the help of a powerful separation method. The proposed strategy will lie firstly by the analysis of simulations (mock-up) of paint materials or artificially aged ones. These model samples will be analyzed in part by Py-GCxGC/MS and by TOF-SIMS, and this approach based on a material multimodal analysis, with no doubt, will make it possible to better understand the complexity of the mass spectra obtained in TOF-SIMS imaging. Especially, a particular effort will be made to identify resins and waxes, which are more difficult to characterize in TOF-SIMS until now, as well as to mixtures between pigments and binders or between very thin layers of different binders themselves.

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