In the present paper optical absorption (OA) studies of RbBr0.95 I0.05: Eu2+, Tl+ mixed crystal are reported. Optical absorption spectrum of RbBr: Tl+ (0.02mol %) can be reproduced for sake of comparison (communicated) shows a band around 4.8eV which is rather flat at its peak. In addition to this, a broad band around 5.6 and 6.0eV on the rising portion of the absorption in the high energy side is observed. In the case of mixed crystal showed that the characteristic Aabsorption band of Tl+ ions in RbBr0.95 I0.05: Tl+ (0.02mol %) mixed crystal broadened towards the low energy side with iodine composition. The change in the absorption spectrum of mixed crystal is suggested to be due to complex centers involving Br- and I- ions formed in the mixed crystal. But in the case of Tl+ co-doped RbBr0.95 I0.05:Eu2+ mixed crystal exhibits structured absorption band in the range between 2.8 to 4.0eV in addition with a shoulder around 4.2 and 5.07eV are observed. The broad and structured bands from 2.8 to 4.0eV may contain several absorption bands due to Eu2+ and Tl+ ions and their aggregates
