title: X-ray Excitation Triggers Ytterbium Anomalous Emission in CaF2:Yb but Not in SrF2:Yb.
abstract: Materials that luminesce after excitation with ionizing radiation are extensively applied in physics, medicine, security, and industry. Lanthanide dopants are known to trigger crystal scintillation through their fast d-f emissions; the same is true for other important applications as lasers or phosphors for lighting. However, this ability can be seriously compromised by unwanted anomalous emissions often found with the most common lanthanide activators. We report high-resolution X-ray-excited optical (IR to UV) luminescence spectra of CaF2:Yb and SrF2:Yb samples excited at 8949 eV and 80 K. Ionizing radiation excites the known anomalous emission of ytterbium in the CaF2host but not in the SrF2host. Wave function-based ab initio calculations of host-to-dopant electron transfer and Yb2+/Yb3+intervalence charge transfer explain the difference. The model also explains the lack of anomalous emission in Yb-doped SrF2excited by VUV radiation.
authors.affiliation: Department of Physics and Astronomy, University of Canterbury , PB 4800, Christchurch 8140, New Zealand.
authors.forename: Rosa B
authors.initials: RB
authors.lastname: Hughes-Currie
authors.affiliation: Department of Physics and Astronomy, University of Canterbury , PB 4800, Christchurch 8140, New Zealand.|Institute of Physics and Technology, Ural Federal University , 620002 Ekaterinburg, Russia.
authors.forename: Konstantin V
authors.initials: KV
authors.lastname: Ivanovskikh
authors.affiliation: Dodd-Walls Centre for Quantum and Photonic Technologies, Department of Physics and Astronomy, University of Canterbury , PB 4800, Christchurch 8140, New Zealand.
authors.forename: Jon-Paul R
authors.initials: JR
authors.lastname: Wells
authors.affiliation: Dodd-Walls Centre for Quantum and Photonic Technologies, Department of Physics and Astronomy, University of Canterbury , PB 4800, Christchurch 8140, New Zealand.
authors.forename: Michael F
authors.initials: MF
authors.lastname: Reid
authors.affiliation: Moyie Institute and Deptartment of Physics, Simon Fraser University , Burnaby V5A 1S6, British Columbia, Canada.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Gordon
authors.affiliation: Departamento de Química, Instituto Universitario de Ciencia de Materiales Nicolás Cabrera, and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid , 28049 Madrid, Spain.
authors.forename: Luis
authors.initials: L
authors.lastname: Seijo
authors.affiliation: Departamento de Química, Instituto Universitario de Ciencia de Materiales Nicolás Cabrera, and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid , 28049 Madrid, Spain.
authors.forename: Zoila
authors.identifier: http://orcid.org/0000-0001-7166-6844
authors.initials: Z
authors.lastname: Barandiarán