Mitigation strategies for radiation damage in the analysis of ancient materials

Bertrand, Loïc; Schoeder, Sebastian; Anglos, Demetrios; Breese, M.B.H.; Janssens, Koen; Moini, Mehdi; Simón, A.

doi:10.1016/j.trac.2014.10.005

Cited by 106 publications

(73 citation statements)

References 114 publications

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“…28 This awareness stems not only from the significance of those materials -they are unique testimonies of our past-, but also from their very nature: because they are mostly heterogeneous in chemical composition, in phase distribution and in topology, their spectroscopic investigation requires the use of micro-probes usually coupled to high photon fluxes, leading to high photon doses absorbed by the sample. The pigment…”

Section: Discussionmentioning

confidence: 99%

X-ray Photochemistry of Prussian Blue Cellulosic Materials: Evidence for a Substrate-Mediated Redox Process

et al. 2015

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Beside its promising applications in the design of multifunctional materials, batteries and biosensors, the pigment Prussian blue is still studied in heritage science because of its capricious fading behavior due to a complex light-induced redox mechanism. We studied model heritage materials composed of Prussian blue embedded into a cellulosic fiber substrate by means of X-ray absorption near-edge spectroscopy. Significant X-ray radiation damage was observed and characterized. X-ray radiation induced first a reduction of Prussian blue, in a similar way to what visible light does, followed by a complete degradation of the pigment and the formation of iron(III) oxyhydroxide. We took advantage of this X-ray photochemistry to investigate in depth the redox behavior of Prussian blue. We could particularly demonstrate that the rate, extent, and quality of Prussian blue photoreduction can be tuned by modifying the pH and alkali cation content of the cellulosic substrate. The present study represents a step further in the understanding of Prussian blue heritage materials from an electrochemical viewpoint and provides evidence of substrate-mediated photochemistry applicable to a wider class of Prussian blue composite materials.

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Section: Discussionmentioning

confidence: 99%

X-ray Photochemistry of Prussian Blue Cellulosic Materials: Evidence for a Substrate-Mediated Redox Process

et al. 2015

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“…The observation of beam-induced changes during the characterization of cultural heritage materials by intense radiation sources (synchrotron radiation, ion and laser beams) has revealed the necessity of studying radiation damage mechanisms and has encouraged the development of mitigation strategies [1]. Both issues are relevant for the analysis of paintings, given the known sensitivity of pigments and painting materials to irradiation by proton induced X-ray emission (PIXE) [2 and references therein], by synchrotron X-rays [3] or by lasers [4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

X-ray and ion irradiation effects on azurite, malachite and alizarin pictorial models

Carrasco

Oujja

Sanz

et al. 2018

Microchemical Journal

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The analysis by intense radiation sources of painting materials used in artworks gives valuable information about their composition and state of conservation, but it can also induce undesired modifications on the studied substrates. Here we use X-ray photoelectron spectroscopy (XPS) to follow the surface chemical changes that prolonged irradiation with soft X-rays (with maximum doses ranging from ~ 1.2x10 17 to ~ 3.4x10 17 photons cm -2 ) produce on azurite, malachite and alizarin pigments and on two egg-yolk temperas containing azurite or alizarin. The effects following exposure to Argon ion irradiation have been also studied for malachite and azurite tempera. XPS spectra of the samples show that both types of radiation induce similar superficial alterations, although, at the selected experimental conditions, the modification rate is slower for exposure to soft X-rays. The highest radiation stability is shown for alizarin and, on the contrary, azurite and malachite experience a progressive chemical reduction of Cu 2+ to Cu + . The reduction of copper takes also place in the azurite tempera, while the proteins and lipids of the egg-yolk binder of azurite and alizarin temperas are subjected to degradation by irradiation with photons and ions. By employing XPS, the cleavage of C-N, C-O(H) and C=O bonds has been identified in the egg-yolk temperas.

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“…Although care should be taken when exposing photosensitive pigments to energetic X-rays,t he dose deposited onto the painting during the MA-XRPD analyses was about 10 7 times smaller compared to typical XRPD SR investigations. [7] Thet wo-dimensional (2D) X-ray patterns collected at each pixel location were azimuthally integrated to onedimensional (1D) diffractograms (diffracted intensity versus scattering angle,2 q,o rm omentum transfer, Q). These profiles can be described with am odel of which the parameters are determined by al east-squares fitting.…”

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confidence: 99%

Chemical Mapping by Macroscopic X‐ray Powder Diffraction (MA‐XRPD) of Van Gogh's Sunflowers: Identification of Areas with Higher Degradation Risk

et al. 2018

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The discoloration rate of chrome yellow (CY), a class of synthetic inorganic pigments (PbCr S O ) frequently used by Van Gogh and his contemporaries, strongly depends on its sulfate content and on its crystalline structure (either monoclinic or orthorhombic). Macroscopic X-Ray powder diffraction imaging of selected areas on Van Gogh's Sunflowers (Van Gogh Museum, Amsterdam) revealed the presence of two subtypes of CY: the light-fast monoclinic PbCrO (LF-CY) and the light-sensitive monoclinic PbCr S O (x≈0.5; LS-CY). The latter was encountered in large parts of the painting (e.g., in the pale-yellow background and the bright-yellow petals, but also in the green stems and flower hearts), thus indicating their higher risk for past or future darkening. Overall, it is present in more than 50 % of the CY regions. Preferred orientation of LS-CY allows observation of a significant ordering of the elongated crystallites along the direction of Van Gogh's brush strokes.

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Mitigation strategies for radiation damage in the analysis of ancient materials

Cited by 106 publications

References 114 publications

X-ray Photochemistry of Prussian Blue Cellulosic Materials: Evidence for a Substrate-Mediated Redox Process

X-ray Photochemistry of Prussian Blue Cellulosic Materials: Evidence for a Substrate-Mediated Redox Process

X-ray and ion irradiation effects on azurite, malachite and alizarin pictorial models

Chemical Mapping by Macroscopic X‐ray Powder Diffraction (MA‐XRPD) of Van Gogh's Sunflowers: Identification of Areas with Higher Degradation Risk

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