Vacuum ultraviolet spectroscopy of Ce³⁺-doped SrMgF₄with 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.

A far ultraviolet spectroscopic study of the reflectance, luminescence and electronic properties of SrMgF4 single crystals

“…8) match well the oscillator energies E r and E 1 (Tab. 2), their origin can not be explained by surface energy loss, band profiles can not be approximated by the formula (5) at reasonable values of the approximation parameters. In addition, B and D bands partially overlap with the dominant C band.…”

“…Study of this aspect has been the subject of several research papers on the luminescence of SMF, doped with rare earth elements. PL emission spectra of Ce 3+ impurity ions in non-equivalent positions of the SMF crystal lattice were studied upon excitation in the 100-600 nm spectral region at temperatures of 17-300 K [5,6]. PL emission spectra of Sm 2+ have been investigated at the excitation energy 2.54 eV (488 nm) in host lattices of SMF [7] and Ba 1−δ Sr δ MgF 4 (δ < 0.55) [8].…”

Photoluminescence and magnetic properties of CdPS3 intercalated with rare earth ions

“…3 shows the PL spectrum of D Ce at 4.2 K. It is due to the 4f → 5d transition of Ce 3+ ions in the lamellar layers. It can be deconvoluted to four Gaussian spectra of which peak wave numbers are 13,250, 19,000, 22,600 and 24,200 cm −1 , respectively [7]. Each deconvoluted spectrum is considered to be originated from the different luminescent centers.…”

Electronic excitations and luminescence of SrMgF4 single crystals

“…Second, the presence of a large number of nonequivalent positions for the introduction of impurity atoms in the structure makes it possible to control the luminescent properties of the SMF compound over a wide spectral range. This aspect of the problem has been investigated in a number of works on the photoluminescence (PL) of SMF crystals doped with rare-earth elements: the PL emission spectra of Ce 3+ impurity ions in non equivalent positions of the SMF crystal lattice were examined under excitation in the wavelength range from 100 to 600 nm at temperatures of 17-300 K [5,6]; the Sm 2+ PL emission spectra were studied at an excitation energy of 2.54 eV (488 nm) in host lattices of SMF [7] and Ba 1−δ Sr δ MgF 4 (δ < 0.55) [8]; and * igor.ogorodnikov@bk.ru the PL emission spectra of europium and terbium impurity ions in different charge states were investigated in [9,10]. Third, the disordering of the crystal lattice should affect the spectral and luminescent properties of intrinsic lattice defects in SMF.…”