Color Center in Amethyst Quartz

@article{Lehmann1966ColorCI,
  title={Color Center in Amethyst Quartz},
  author={G. Lehmann and W. J. Moore},
  journal={Science},
  year={1966},
  volume={152},
  pages={1061 - 1062}
}
Treatment with x-rays increased the intensity of color of natural amethyst up to fivefold, and an electron paramagnetic resonance spectrum was detected. The intensity of the spectrum was proportional to the intensity of the optical absorption near 545 m�. The EPR spectrum of the color center corresponded to a positive hole trapped on a substitutional Fe3+ ion in the quartz structure. We ascribe the color to a charge-transfer transition, Fe4+ + O2— → Fe3+ + O1-. 
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A detailed description is given of the EPR spectrum of Fe3+ in synthetic brown quartz (the so‐called I center, presumed to be interstitial). There are three equally populated sites differing only inExpand
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References

SHOWING 1-6 OF 6 REFERENCES
Paramagnetic Resonance and Optical Properties of Amethyst
Color centers in amethyst are produced by action of ionizing radiation on precursor centers which arise from substitution of Fe3+ for Si4+ in the α‐quartz structure, with charge neutralizationExpand
The Spectra and Electronic Structure of the Tetrahedral Ions MnO4−, CrO4−−, and ClO4−
We have made use of a semiempirical treatment to calculate the energies of the molecular orbitals for the ground state and the first few excited states of permanganate, chromate, and perchlorateExpand
Intensities in inorganic complexes: Part II. Tetrahedral complexes
Abstract An account is given of the modern theories concerning the nature of the electron orbits in tetrahedral inorganic complexes of the first transition series. It is shown that, although theExpand
Chem
  • ISod.
  • 1956
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