X-ray absorption spectroscopy of ultramarine pigments: A new analytical method for the polysulfide radical anion S3− chromophore
| Autor: | Xi Liu, Michael E. Fleet |
|---|---|
| Rok vydání: | 2010 |
| Předmět: |
X-ray absorption spectroscopy
Inorganic chemistry chemistry.chemical_element Chromophore Photochemistry Sulfur Atomic and Molecular Physics and Optics XANES Analytical Chemistry chemistry.chemical_compound Pigment Unpaired electron chemistry visual_art visual_art.visual_art_medium Instrumentation Spectroscopy Polysulfide Lazurite |
| Zdroj: | Spectrochimica Acta Part B: Atomic Spectroscopy. 65:75-79 |
| ISSN: | 0584-8547 |
| Popis: | Blue and mauve ultramarine artists' pigments and their heat-treated products have been investigated by sulfur K -edge X-ray absorption. X-ray absorption near-edge structure spectra are dominated by features of reduced sulfur and sulfate species. There is also a pre-peak at about 2468.0 eV which reflects the presence of the unpaired electron on the polysulfide radical anion (S 3 − ). Pre-peak intensity is directly proportional to the depth of blue coloration, and provides a new, independent method for estimating the proportion of ultramarine cage sites occupied by the blue chromophore. The occupancy of the polysulfide radical anion S 3 − is estimated to be 33% in an intense ultramarine blue pigment, 22% in a dark blue ultramarine pigment, and 1% in deep royal blue lazurite from Afghanistan. The more efficient development of color in lazurite is attributed to extensive annealing of the mineral structure in the natural environment. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect