Abstract

Alkali-halide crystals when doped with heavy-metal ions with the s² configuration show absorption and emission bands which are characteristic of the impurity^(2,3). A close resemblance was observed by us between the absorption spectra of thallium bromide solutions and the spectra of thallium-doped potassium bromide single crystals⁽³⁾ as shown in fig. 1. Furthermore, the same similarity between doped crystals and solutions was also observed in the luminescence spectra on excitation in the UV absorption bands. Fig. 2 reports the emission spectra at Room Temperature of an alcoholic TlBr solution of polycrystalline powder, for two different excitation wavelengths. The spectra consist almost entirely of two overlapping bands with an energy separation of about 0.5 eV and of several shoulders. The spectral positions of the two main structures are the same as in the solid as one can observe in the figure

© 1984 Optical Society of America