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Investigating the origin of the instability of cadmium yellow paint in Pablo Picasso s Femme

Pablo Picasso s painting Femme (1907) contains two cadmium yellow paints, one relatively intact and one visibly degraded. Synchrotron X-ray and photoluminescence techniques were combined to study paint micro-samples, thus determining the chemical and structural differences between the two yellow paints and allowing to identify the key factors that may have caused the degradation.

The painting Femme by Pablo Picasso (1907, Foundation Beyeler, Riehen/Basel) shows a similar motif to the artist s most famous masterpiece Les Demoiselles d Avignon (1907, Museum of Modern Art, New York), an abstract female figure with arms raised. A previous assessment of the painting conditions [1] revealed that the areas of lemon-yellow paint alongside the figure had faded, while the yellow has preserved its vibrant yellow tone (Figure 80). Both paints are based on cadmium yellow (CdS) which, although exposed to the same environmental conditions, has been preserved differently. In this work, micro X-ray fluorescence (µXRF), micro X-ray absorption near-edge spectroscopy (µXANES) and micro X-ray diffraction (µXRD) techniques are combined with micro photoluminescence (µPL) to study paint micro cross-sections and determine potential markers linked to cadmium yellow degradation.

Synchrotron X-ray-based analyses performed at beamlines ID13 and ID21 revealed that the yellow paints are intrinsically different. The relatively intact yellow is composed of a mixture of crystalline hexagonal and cubic CdS with two different extenders [Pb3(CO3)2(OH)2 and BaSO4], while the faded yellow is a mixture of amorphous or nanocrystalline CdS and BaSO4. Several compounds associated with cadmium yellow paint degradation (i.e.,

Fig. 80: Photograph of Femme and photomicrographs of the (a) faded and (b) relatively intact paint micro cross-sections.

CdSO4/3CdSO4·8H2O, sulfite species, CdC2O4) were also found in the faded paint, together with Cd(OH)Cl, amorphous Cd Cl and CdCO3.

µPL measurements (performed at SOLEIL synchrotron) showed that, upon deep-UV excitation, the faded yellow exhibits a heterogeneous emission, with regions brightly emitting in the red or in the near-infrared (NIR) spectral range. Instead, the relatively intact yellow presents a homogeneous emission in the NIR. Both emissions can be ascribed to radiative recombination occurring from deep trap states induced by defects in CdS. However,

PRINCIPAL PUBLICATION AND AUTHORS

Assessing implications of nanoplastics exposure to plants with advanced nanometrology techniques, A.E. Pradas del Real (a,c), D.M. Mitrano (b) H. Castillo-Michel (c), M. Wazne (c,e), J. Reyes-Herrera (c), E. Bortel (d), B. Hesse (c,d), J. Villanova (c), G. Sarret (e), J. Hazard. Mater. 430, 128356 (2022); https:/doi.org/10.1016/j.jhazmat.2022.128356 (a) IMIDRA (Madrid Institute for Agroenvironmental Research), Alcalá de Henares (Spain) (b) ETH Zurich, Zurich (Switzerland) (c) ESRF (d) Xploraytion GmbH, Berlin (Germany) (e) Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD, IFSTTAR, ISTerre, Grenoble (France)

phytotoxicity markers with advanced nanometrology techniques. The next step is to grow plants in soil and to study the possible transfer in the grains. In addition, as

the ageing process(es) of nanoplastics may modify their behavior, complementary studies using nanoplastics after ageing are needed.