THE RELATIONSHIP BETWEEN QUANTUM EFFICIENCY AND AVERAGE LIFETIME OF CR3+ IONS IN GLASS

For Cr3+ ions in crystalline hosts, in which the 4T2 level is at a low er energy than 2E, the variation in tau, the observed lifetime, should provide a measure of the variation in quantum efficiency. This is not the case for Cr3+ ions in glass; in glass the quantum efficiency fall s with increasing temperature much more rapidly than the average lifet imes [tau]. We show that this is caused by the occurrence in glass of Cr3+ ions with distinctly different non-radiative rates. We investigat e this effect to see if it can provide information about the distribut ion of non-radiative rates among the Cr3+ ions.