Identification of Eu oxidation states in a doped Sr_5(PO_4)_3F phosphor by TOF-SIMS imaging Swart, H. C. ; Nagpure, I. M. ; Ntwaeaborwa, O. M. ; Fisher, G. L. ; Terblans, J. J. Abstract Publication: Optics Express Pub Date: July 2012 DOI: 10.1364/OE.20.017119 Bibcode: 2012OExpr..2017119S