The luminescence of Bi, Ag and Cu in natural and synthetic barite BaSO4

The time-resolved laser-induced luminescence of natural barite BaSO4 is com pared with synthetically prepared BaSO4-Bi, BaSO4-Ag and BaSO4-Cu. It is de duced that in natural barite the narrow orange band with lambda (max) = 625 nm. Delta = 40 nm and tau = 5 mus is connected with Bi2+ center. The narro w violet band with lambda (max) = 625 nm, Delta = 35 nm and tau = 1.7 ms is connected with Bi3+ center. The broad red band with lambda (max) = 635 nm, Delta = 140 nm and tau = 270 mus is connected with Ag+ center. The broad r ed band with lambda (max) = 750 nm, Delta = 110 nm and tau = 350 mus is con nected with Cu+ center. Such luminescence centers are firstly considered in minerals. (C) 2001 Elsevier Science B.V. All rights reserved.