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Probing the chemistry of CdS paints in The Scream by in situ noninvasive spectroscopies and synchrotron radiation x-ray techniques

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Science Advances  15 May 2020:
Vol. 6, no. 20, eaay3514
DOI: 10.1126/sciadv.aay3514
  • Fig. 1 Degraded cadmium yellow paints and ultraviolet–visible–near-infrared spectroscopy single-point analysis in The Scream (ca. 1910).

    Photograph of The Scream (ca. 1910) (Munch Museum, Oslo; catalog no. Woll.M.896) and overview of the areas where ultraviolet–visible–near-infrared (UV-vis-NIR) reflection and fluorescence spectroscopy single-point measurements were performed (see Fig. 2 and fig. S1 for the corresponding spectra). Arrows show the sampling spot and the degraded cadmium yellow paints. Photo credit: Irina Crina Anca Sandu and Eva Storevik Tveit, Munch Museum.

  • Fig. 2 Sky and lake regions: In situ noninvasive spectroscopic results.

    (A) Photograph of a detail of the sky and lake areas of The Scream (ca. 1910) and (B) corresponding composite red-green (RG) MA-XRF maps of Cd (red) and Cl (green). Photo credit: Irina Crina Anca Sandu and Eva Storevik Tveit, Munch Museum. (C) Spatial distribution of CdS luminescence with λmax at 775 nm [Paint (c)]. (D to F) UV-vis-NIR reflectance and fluorescence spectra and (G to I) FTIR pseudo-absorbance profiles recorded from selected CdS-based areas of the sky (pts. 1 to 3 and 6) and of the lake (pts. 4 and 5) compared to those of chosen reference compounds (gray). In (E), (F), (H), and (I), numbers in brackets refer to the spectra showing similar features to those shown (see Fig. 1 and fig. S1 for additional UV-vis-NIR spectroscopy results). Asterisks in (D) to (F) indicate a signal not related to CdS but likely due to both the reflection/scattering of the excitation source and the emission of the binder and/or other fluorophores.

  • Fig. 3 Microflake ScMM01: S speciation results.

    (A) Photomicrograph of microflake ScMM01 taken from The Scream (ca. 1910) (see Fig. 1 for the sampling spot) and corresponding SR μ-XRD distribution of (B) hex-CdS and (C) Cd(OH)Cl/CdSO4/CdCO3 [step size (h × v), 2 × 2 μm2; exp. time, 10 s per pixel; energy, 8.5 keV]. (D) Composite red-green-blue (RGB) SR μ-XRF maps of S-II/SVI/Cd [step size (h × v), 0.8 × 0.8 μm2; exp. time, 100 ms per pixe]. (E) Selection of S K-edge spectra (black) and result of the linear combination fitting (LCF) (cyan) of different S-based compounds obtained from the spots indicated in (D). In gray, the spectral profiles of selected reference compounds are reported for comparison. Numbers in brackets refer to the spectra showing similar features to those reported (see Fig. 4 for the corresponding Cl speciation results).

  • Fig. 4 Microflakes: Cl speciation results.

    Composite RG SR μ-XRF maps of Cl/K recorded from microflakes (A) ScMM01 and (B) ScMM02 [step size (h × v), 0.8 × 0.8 μm2; exp. time, 100 ms per pixel]. Selection of the Cl K-edge spectra (black) compared to those of different Cl reference compounds (gray) obtained from (C) ScMM01 and (D) ScMM02. Spectral profiles were recorded from the spots indicated in (A) and (B). In (C) and (D), numbers in brackets refer to the spectra showing similar features to those reported (see Fig. 3 for the corresponding S speciation results).

  • Fig. 5 Unaged early 20th century cadmium yellow oil paint mock-up (7914).

    (A) Photomicrograph of 7914 thin section before aging and corresponding RGB composite (B) SR μ-XRD maps of hex-CdS/Cd(OH)Cl/CdCO3 [step size (h × v), 1 × 1 μm2; exp. time, 1 s per pixel; energy, 21 keV] and (C) SR μ-XRF maps of S-II/Cl/Cd [step size (h × v), 1×1 μm2; exp. time, 100 ms per pixel] recorded from the area shown in (A). Selection of μ-XANES spectra at (D) S K-edge and (E) Cl K-edge obtained from the points indicated in (C) and LCF results (cyan) of different S-based reference compounds. In (D) and (E), the spectral profiles of selected reference compounds are reported in gray color for comparison, whereas numbers in brackets refer to the spectra showing similar features to those reported (see table S1 for additional results).

  • Fig. 6 Artificially aged 7914 mock-up.

    (A) Photomicrograph of 7914 thin section after thermal aging (RH ≥ 95%, T = 40°C, 90 days). (B) Quantitative Cd phase images obtained from the LCF of the full-field (FF)–XANES stack using the profiles of CdS (red), CdSO4·nH2O/(Cd,Cl) chlorides (green), and CdC2O4·3H2O/CdCO3 (blue). RGB composite (C) SR μ-XRD images of hex-CdS/Cd(OH)Cl/CdCO3 [step size (h × v), 1.5 × 1.5 μm2; exp. time, 1 s per pixel; energy, 21 keV] and (D) SR μ-XRF maps of S-II/SVI [step size (h × v), 1 × 1 μm2; exp. time, 100 ms per pixel] acquired from the regions shown in (A). Selection of μ-XANES spectra at (E) S K-edge and (F) Cl K-edge obtained from the points indicated in (D) and LCF results (cyan) of different S-based reference compounds. In (E) and (F), the spectral profiles of selected reference compounds are reported in gray color for comparison, whereas numbers in brackets refer to the spectra showing similar features to those reported (see figs. S3 to S5 and table S1 for additional results).

  • Fig. 7 Munch’s cadmium yellow lemon oil paint tube (LFG 2.4).

    Photomicrographs of LFG 2.4 thin sections (A) before and (E) after thermal aging (RH ≥ 95%, T = 40°C, 90 days). RGB composite SR μ-XRF images of (B) S-II/SVI and (C) Cl/Cd [step size (h × v), 1 × 1 μm2; exp. time, 100 ms per pixel] recorded from the area shown in (A). (D) Selection of S K-edge μ-XANES spectra (black) obtained from the points indicated in (B) and corresponding LCF results (cyan). RGB composite SR μ-XRF images of (F) S-II/SVI and (G) Na/Cl/Cd [step size (h × v), 1 × 0.8 μm2; exp. time, 80 ms per pixel] acquired from the region illustrated in (E). (H) Selection of S K-edge μ-XANES spectra (black) obtained from the points indicated in (F) and LCF results (cyan). In (D) and (H), numbers in brackets indicate the profiles showing similar spectral features to those shown (see fig. S6 and table S1 for further results).

Supplementary Materials

  • Supplementary Materials

    Probing the chemistry of CdS paints in The Scream by in situ noninvasive spectroscopies and synchrotron radiation x-ray techniques

    Letizia Monico, Laura Cartechini, Francesca Rosi, Annalisa Chieli, Chiara Grazia, Steven De Meyer, Gert Nuyts, Frederik Vanmeert, Koen Janssens, Marine Cotte, Wout De Nolf, Gerald Falkenberg, Irina Crina Anca Sandu, Eva Storevik Tveit, Jennifer Mass, Renato Pereira de Freitas, Aldo Romani, Costanza Miliani

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    • Sections S1 to S4
    • Figs. S1 to S8
    • Table S1
    • References

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