Soft x-ray excitation of luminescence in wide band crystals

Luminescence excitation spectra of wide bandgap oxide crystals were measured in the soft X-ray range of excitation (300-750 eV) at the BEAR beamline of the electron storage ring Elettra (Trieste). We give a special attention to changes of the light yield in the vicinity of the absorption K-edge of oxygen. The excitation spectra of two well-known scintillators YAG-Yb and LuAP-Ce (chemical formulae are Y3Al5O12:Yb (15%) and LuAlO5:Ce (0.4%)) reveal a non-proportional change of the quantum yield and a different response to the jump of absorption coefficient at the 1sO edge for certain emission bands. The analysis of experimental data shows that both the surface loss and interaction effects between secondary electronic excitations (EEs) can influence the energy conversion process in crystals