physica status solidi (b)
© WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Editor: Stefan Hildebrandt (Editor-in-Chief), Sabine Bahrs (Deputy Editor)
Online ISSN: 1521-3951
Optical absorption spectra of Fe2+ and Fe3+ in beryl crystals
The cover picture of this issue relates to the article by G. Spinolo et al. on optical absorption spectra of Fe ions in beryl crystals . It shows the low temperature polarized light absorption spectrum of a gem-quality natural aquamarine, i.e. an iron rich beryl. The relevant achievement is that satisfactory attributions of the numerous peaks of the spectrum may be obtained only assuming that both Fe2+ and Fe3+ are substituted for Al in an octahedral oxygen environment. This result excludes the possibility, proposed by several authors, of alternative locations (tetrahedral or “channel“ sites) for iron in beryl. The paper also discusses the ligand-to-metal (probably Fe3+) charge transfer spectrum which was measured in beryl for the first time.
The corresponding author Giorgio Spinolo is a Professor of Physics at Milano–Bicocca University, Italy. After early studies on color centers in alkali halides, he became interested in intrinsic optical properties of transition metal halides and later in silica for electronic and photonic applications. Nowadays, his research is devoted to promote a solid state physics approach to study minerals of gemological interest. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)