Tof-SIMS spectra of historical inorganic pigments Free

Cultural Heritage materials, like historical paintings, are complex heterogeneous objects comprising multiple microstructures with various organic and inorganic natural or synthetic materials. Additionally, they often have aged within uncontrolled environments, sometimes over centuries. Mass spectrometry imaging techniques are helpful to investigate the resulting heterogeneous microstructures, providing additional knowledge on artwork’s nature and state of preservation. ToF-SIMS has growing relevance, as it offers the possibility to simultaneously detect and map both organic and inorganic materials on the micrometric scale.

However, because a large variety of compounds expected to be found in Cultural Heritage materials are heterogeneous at the microscale, it is crucial to be able to have a clear understanding of the link between the local signal detected and the original historical material in the sampled area. For such confident identifications to be possible, comparison with spectra acquired on a ToF-SIMS instrument from historically relevant references is mandatory. Indeed, most reference spectra available in the literature are for other MS techniques, such as GC-MS, which may not characterize the secondary ions formed at the surface of a sample when using ToF-SIMS. As it is not routinely applied to Cultural Heritage materials, most published ToF-SIMS studies remain case reports. This lack of accessible and documented reference data makes informed analysis difficult and underscores the need for dedicated databases.

In this context, the present collection aims at building the basis of an extensive library of reference ToF-SIMS data for a selection of pigments used prior to the industrial revolution, containing diverse metallic oxides, hydroxides, carbonates, and hydrocarbons. The materials used as reference specimens, summarized in Table I, are as historically relevant as possible, purchased from manufacturers specialized in reproducing historical recipes. Each specimen is described and the major peaks for both polarities are assigned.

This collection not only leads to a better understanding of capabilities and limitations of the technique but also strengthens the link between detected ions and chemical structures with greater confidence. The papers in the collection represent a unique set of data allowing for comparison with readers’ own ion signals. This meets the need for improved accessibility of the results obtained with ToF-SIMS towards a broader scientific audience working on Cultural Heritage materials.