Thermal Quenching of Cr(III) Luminescence

摘要

The luminescences of chromium acetylacetonate and the nitrohyphen; and haloderivatives dissolved in three different isomorphous crystalline hosts have been studied as a function of temperature. The lifetimes and relative quantum yields were determined and evidence for two thermally activated nonradiative processes has been obtained. The activation energies and frequency factors areE11 kcal/mole,s1sime;103secminus;1andE2sime;7 kcal/mole,s2sime;1012secminus;1. This latter value is very large for a spinhyphen;forbidden process. The lattice appears to affect nonradiative processes originating in the4T2more than those involving the2Estate.