Absorption and emission spectra of thallium activated Na2O-NaCl-B2O3 and K2O-KCl-B2O3 glasses

Absorption and emission spectra of two Na₂O-NaCl-B₂O₃ and two K₂O-KCl-B₂O₃ glasses, with large thallium concentrations (about 0.01 mol thallium per litre glass) have been studied. Absorption bands have been observed at 49 000, 44 500 and 40 000 cm^?1 for the Na₂O-NaCl-B₂O₃ glasses, and at 49 000, 43 500 and 38 500 cm^?1 for the K₂O-KCl-B₂O₃ glasses at 300 K. Emission spectra have been recorded at 83, 308, 445 and 485 K; generally two emission bands have been observed in the ultraviolet region, and the intensity of both bands increased with decreasing temperature. The absorption and emission bands have been assigned to electronic transitions in different centres formed by Tl⁺ ions in glass.