ENERGY-TRANSFER PROCESSES IN RARE-EARTH DOPED ZNS UNDER NONLINEAR EXCITATION

ZnS:Sm3+ single crystals are studied by site selective, time resolved and decay time measurements. It will be shown that beside the direct 4f-4f excitation a slow energy transfer component occurs that can be attributed to the blue self-activated emission in ZnS. Analysing the decay behaviour of various Sm3+ sites in detail a fast transfer component could be selected which is active for only some of the Sm3+ sites. The nature of the energy transfer processes will be discussed basing on decay fits and conclusions will be drawn on the differences between Sm3+ centers, which provides to a better understanding of the luminescence data.