Structural Analysis of Freshwater-Cultured Pearls with Different Lusters Using the Extended X-Ray Absorption Fine Structure Technique

The quality of freshwater-cultured pearls (Chamberlainia hainesiana) is determined by their luster, which is related to the content of the two CaCO 3 mineral phases: aragonite and vaterite. The atomic structures of pearl samples were analyzed by the extended X-ray absorption fine structure (EXAFS) t...

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Bibliographic Details
Published in:Journal of applied spectroscopy 2016-05, Vol.83 (2), p.298-301
Main Authors: Monarumit, N., Noirawee, N., Phlayrahan, A., Promdee, K., Won-in, K., Satitkune, S.
Format: Article
Language:English
Subjects:
Analytical Chemistry
Atomic/Molecular Structure and Spectra
Calcite crystals
Methods
Particle accelerators
Physics
Physics and Astronomy
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Summary:The quality of freshwater-cultured pearls (Chamberlainia hainesiana) is determined by their luster, which is related to the content of the two CaCO 3 mineral phases: aragonite and vaterite. The atomic structures of pearl samples were analyzed by the extended X-ray absorption fine structure (EXAFS) technique using synchrotron radiation to compare the atomic environment and atomic bonding around Ca atoms of high- and low-luster pearls. The Ca K-edge EXAFS spectra of the pearl samples were determined and interpreted in terms of the photoelectron wave number and the distance between Ca atoms and neighboring atoms. From the results, the wave oscillation of high-luster pearls is less than that of low-luster pearls. This indicates the presence of the aragonite phase in high-luster pearls and a combination of aragonite and vaterite phases in low-luster pearls, especially in the fi rst and second shells of Ca atoms. It can be concluded that the different lusters of freshwater-cultured pearls are related to the different CaCO 3 phases in their structures.
ISSN:0021-9037
1573-8647
DOI:10.1007/s10812-016-0285-2