SITE SELECTION SPECTROSCOPY OF CR3+ IN MGAL2O4 GREEN SPINEL

The optical properties of Cr3+ ions in the synthetic green spinel MgAl 2O4 were re-examined by means of site selection spectroscopy; In parti cular, our attention was focused on the distribution of Cr3+ sites emb edded in this disordered crystal. By means of site selection excitatio n spectroscopy, a number of Cr3+ classes associated with strong, inter mediate and weak ligand field sites were identified. The fluorescence line narrowing technique was used to establish the 25 Cr3+ sites. The splitting of the (4)A(2) level was determined to be 1.7 cm(-1). It was found that in higher concentrated samples the number of weak ligand f ield Cr3+ sites is increasing.