Luminescence studies in colour centres produced in natural topaz

Luminescence emission bands originating in colour centres produced in natur al topaz have been detected. These bands are studied by steady-state and ti me-resolved photoluminescence spectroscopy. We found that the energy of the emitting bands are different in colourless samples and in samples submitte d to treatment and depend on the treatment itself. Also, there is an emissi on present in long-lived detection regimes, indicating the possible presenc e of non-radiative processes. These results are analysed and a possible cor relation between structural and colour changes resulting from the irradiati on and annealing treatment is addressed. (C) 2000 Elsevier Science B.V. All rights reserved.