The variation of inhomogeneous and homogeneous line width with x for Sm2+ ions in BaFClxBr1-x was studied by fluorescence line narrowing (FLN) and spectral hole-burning (HB). The ratios N of inhomogeneous width to homogeneous width approach a maximum for x = 0.8, 0.5. N is about 80 for transition from 7F0 to 5D2 of BaFCl0.5Br0.5 at 77 K. The inhomogeneous lines for transitions between 5DJ and 7F0 of Sm2+ ions in BaFClxBr1-x (x = 0.8, 0.5, 0.2) have novel double-peaked shape. According to the FLN study, these novel shapes are explained by different probabilities of Cl and Br ligand configurations around Sm2+. These novel shapes significantly broaden the inhomogeneous line width of Sm2+ and make hole burning available at 77 K. This might have an important implication on frequency domain optical storage. © 1990.
