Humeyra Orucu

Site-selective spectroscopy of garnet crystals doped with chromium ions.

Site-selective spectroscopy is a tool that can be used to uncover the presence of multiple sites available to optically active ions in host lattices. In this Article, we present techniques that can be applied to appraise the different sites that may occur in systems where charge compensation is required or in systems where such compensation is not present. We then consider some garnet crystals doped with chromium ions. For the Cr-doped garnets (YAG, GGG, GSGG, and CYMGG), we present luminescence and lifetime data over a wide temperature range, and infer not only the presence of different centers, but also the interaction among them as a function of temperature.

Photoluminescence spectroscopy of Cr3+ in CaY2Mg2Ge3O12

We have conducted a thorough investigation of the luminescence spectrum of Cr3+ in CaY2Mg2Ge3O12. The spectrum presents a line whose width is 60 cm−1 at 25 K and 82 cm−1 at 200 K, and a number of peaks of vibronic origin superimposed on a large band that extends from 700 to 800 nm. Going up in temperature the superimposed peaks broaden and disappear while the band persists. The response of the system to pulsed excitation presents at low temperature a great variety of patterns at different wavelengths. These patterns tend to collapse into one as the temperature is raised. This investigation confirms that the continuous interest in Cr-doped garnets is rewarding in terms of interesting experimental results.