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


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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