, Volume 96, Issue 5, pp 308-312
Date: 08 Nov 2012

Anomalous luminescence of impurity-bound excitons in lithium borate crystals doped with cerium ions

Abstract

The spectra and relaxation kinetics of the anomalous (τ < 10 ns) luminescence of Li6GdB3O9:Ce3+ crystals have been experimentally detected. The time-resolved vacuum ultraviolet spectroscopy study has shown that optical transitions at 6.2 eV, caused by the transfer of an electron from the 4f 1 ground state of Ce3+ to autoionizing states near the conduction band bottom of a crystal, lead to the formation of an impurity-bound exciton with the hole component localized on the 4f state of Ce3+ and the electron localized on states of the conduction band bottom. It has been found that the decay of such an exciton in Li6GdB3O9:Ce3+ occurs through radiative recombination, leading to fast luminescence at 4.25 eV. The energy threshold for the formation of the impurity-bound exciton has been determined. The distribution functions of elementary relaxations over the reaction rate constants H(k), which determine the relaxation kinetics and luminescence quenching processes, have been calculated.

Original Russian Text © I.N. Ogorodnikov, V.A. Pustovarov, 2012, published in Pis’ma v Zhurnal Eksperimental’noi i Teoreticheskoi Fiziki, 2012, Vol. 96, No. 5, pp. 338–342.