title: Energy levels of the Ce activator relative to the YAP(Ce) scintillator host.
abstract: The electronic structure of the cerium-activated yttrium aluminum perovskite [YAP(Ce)] scintillator has been studied by core level x-ray spectroscopy and first-principles calculations. X-ray absorption and emission spectra at the oxygen K-edge of YAP(Ce) and CeO2 have been measured and compared with the calculated partial density of states. With the known band gap of CeO2, the measured oxygen K-edge absorption and emission spectra are used to construct a fixed relation between the valence and conduction bands of YAP and CeO2. This allows us to determine the fundamental band gap of YAP to be 8.1 ± 0.3 eV. A comparison between the cerium M4,5-edges x-ray absorption spectra of the YAP(Ce) and Ce model compounds (CeO2, CeF3, and Ce foils) then shows that the Ce activator is in the desired Ce(3+), with a small fraction of Ce(4+) due to oxidization at the surface. Finally, we determine that the ground state 4f(1) energy level of the Ce(3+) activator lies 1.8 ± 0.5 eV above the top of the valence band of the host YAP.
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, CA 94550,USA.
authors.forename: S-W
authors.initials: SW
authors.lastname: Yu
authors.forename: M H
authors.initials: MH
authors.lastname: Carpenter
authors.forename: F
authors.initials: F
authors.lastname: Ponce
authors.forename: S
authors.initials: S
authors.lastname: Friedrich
authors.forename: J-S
authors.initials: JS
authors.lastname: Lee
authors.forename: P
authors.initials: P
authors.lastname: Olalde-Velasco
authors.forename: W L
authors.initials: WL
authors.lastname: Yang
authors.forename: D
authors.initials: D
authors.lastname: Åberg