title: Vacuum ultraviolet spectroscopy of Ce(3+)-doped SrMgF(4) with superlattice structure.
abstract: X-ray diffraction of Ce(3+)-doped SrMgF(4) (SMF:Ce) crystals shows a superlattice structure, reflecting the distribution of Ce(3+) polyhedra centres observed in optical experiments. Optical absorption bands and fluorescence bands from the Ce(3+) polyhedra centres overlap in the vacuum ultraviolet (VUV) and ultraviolet (UV) regions, respectively, so that wide pumping and tuning ranges are expected for laser operation. The SMF:Ce crystals, as well as the isomorphous BaMgF(4), are candidates for a tunable laser gain material with nonlinear properties. The optical absorption, excitation, and fluorescence bands observed in the SMF:Ce crystals at low temperatures are ascribed to five distinct fluorescent centres. Three centres have well-known Ce(3+) optical characters, for example, fluorescence with double peaks separated by 2000 cm(-1) and five resolved absorption/excitation bands. These centres are assigned to Ce(3+)-polyhedra classified by weak and strong crystal fields as a consequence of the superlattice structure. The other two fluorescence bands observed in the visible region have 1.5-2 times larger linewidths than those of the former three bands. These bands are interpreted as optical transitions from complexes consisting of Ce(3+) and one or two electrons trapped at a vacancy of the nearest neighbour F(-) ligand ions.
authors.affiliation: Department of Electrical and Electronic Engineering, Faculty of Engineering, Gifu University, Gifu 501-1193, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Yamaga
authors.forename: E
authors.initials: E
authors.lastname: Hayashi
authors.forename: N
authors.initials: N
authors.lastname: Kodama
authors.forename: K
authors.initials: K
authors.lastname: Itoh
authors.forename: S
authors.initials: S
authors.lastname: Yabashi
authors.forename: Y
authors.initials: Y
authors.lastname: Masui
authors.forename: S
authors.initials: S
authors.lastname: Ono
authors.forename: N
authors.initials: N
authors.lastname: Sarukura
authors.forename: T P J
authors.initials: TP
authors.lastname: Han
authors.forename: H G
authors.initials: HG
authors.lastname: Gallagher