X-ray irradiation effects on Egyptian blue and green pigments

Abstract

EPR investigation of Egyptian blue and green irradiated by synchrotron X-rays has revealed the presence of radiation-induced defects (intrinsic and impurities) in both pigments. The green pigment is much more sensitive than the blue (browning).

Non-resonant inelastic X-ray scattering for discrimination of pigments

“…Although most significant changes were identified for pigments associated with binding media, 46,47 alteration was also reported for unsupported powder pigments, particularly when using micro-focused low-energy X-ray beams. 48,49 The absence of alteration observed in our experiments is attributed to the use of a large beam, with correspondingly low fluences (Table S2.1, ESI†) and high energy X-rays, which interact significantly less with mater than low energy photons because of the reduced photoelectric cross-section. However, a colour change was observed post-analysis on the raster-scanned paint.…”

A Combined Experimental and Computational Approach to Understanding CdS Pigment Oxidation in a Renowned Early 20th Century Painting

“…The linear combination fitting (LCF) permitted the quantitative determination of the average relative amount of sulfate (S VI ), sulfite (S IV ), and sulfide (S –II ) compounds (expressed as %[S VI ]/[S total ], %[S IV ]/[S total ], and %[S –II ]/[S total ], respectively) and of different Cd and Cl compounds. Because of the well-known sensitivity of the pigments and other components of the paints under the exposure to SR X-ray microprobes, − care was taken to ensure that the spectra were not affected by the measurement process.…”