Mechanism of X-ray excited optical luminescence (XEOL) in europium doped BaAl2O4 phosphor

This paper reports a luminescence mechanism in Eu-doped BaAl2O4 excited with monochromatic X-rays (also known as X-ray excited optical luminescence - XEOL) from synchrotron radiation. The material was prepared via a proteic sol-gel methodology. The X-ray absorption near edge structures (XANES) at the Ba L-III- and Eu L-III-edges exhibit typical absorption spectra. XEOL spectra recorded in energy ranges, either around the Ba L-III- or Eu L-III-edges, showed important differences concerning the intensity of the Eu2+ or Eu3+ emission bands. Nevertheless, the total area under the XEOL spectra increases as the energy of the X-ray photons increases in both ranges (Ba L-III- and Eu L-III-edges).