The darkening of copper- or lead-based pigments explained by a structural modification of natural orpiment: a spectroscopic and electrochemical study KU Leuven University of Antwerp
© 2017 The Royal Society of Chemistry. A combined Raman and electrochemical study of natural orpiment (As2S3), an arsenic sulfide pigment, was used to assess the quick formation of oxidized species such as arsenic oxide (As2O3) upon exposing the pigment to 405 nm or 532 nm monochromatic light while simultaneously recording the Raman spectra of the exposed sample. During this process, a distortion of the main band at 355 cm-1, associated with the ...