X-ray excited optical luminescence from lanthanide ions in double phosphate and double silicate crystalline hosts

X-ray Excited Optical Luminescence (XEOL) from rare earth doped whitlockite phosphates and silicate garnets [Ca9La(PO4)7 and Ca9Lu(PO4)7, doped with 1 mol% Ce3+; Ca3Sc2Si3O12, doped with 0.5 mol% Pr3+, 1 mol% Eu3+ and 1 mol% Tb3+], was obtained upon X-ray excitation with a tunable synchrotron light source. Excitation at photon energies across the M5,4-edge of the dopants reveals additional information not normally obtainable with conventional UV/visible or an X-ray line source (Al K alpha). It is found that despite the low concentration, photoluminescence yields excited with photon energy at the M5,4-edge of the rare -earth dopant can positively and negatively affect the overall energy transfer to the optical center. The implication of these observations is discussed. The application of XEOL in the investigation of X-ray scintillators is illustrated.