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Optical absorption spectra of Fe 2+ and Fe 3+ in beryl crystals
Author(s) -
Spinolo G.,
Fontana I.,
Galli A.
Publication year - 2007
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200743102
Subject(s) - octahedron , absorption spectroscopy , spectral line , absorption (acoustics) , analytical chemistry (journal) , spectroscopy , chemistry , metal , aqueous solution , crystallography , physics , crystal structure , optics , organic chemistry , chromatography , quantum mechanics , astronomy
A variety of beryls, inclusive of blue aquamarine, heliodor and goshenite, spanning an iron concentration range of more than one order of magnitude, has been studied by absorption spectroscopy down to 16 K and in the energy range 3000–50000 cm –1 . The weak spin‐forbidden transitions of Fe 2+ as well as the allowed charge‐transfer transitions, ligand‐to‐metal, mainly due to Fe 3+ , have been observed for the first time in these diluted systems. The comparison with reference spectra of aqueous solutions containing Fe 2+ and Fe 3+ allowed to reach, by the aid of d 6 (Fe 2+ ) and d 5 (Fe 3+ ) Tanabe‐Sugano diagrams for octahedral symmetry, a satisfactory interpretation of the spectra. The colour centres absorption, their thermal instability and contribution to the colour of these crystals has also been considered. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)