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Abstract: Pr3+, Mn2+ singly doped and co-doped LaMgB5O10 samples were prepared by solid-state reaction and their spectroscopic properties were investigated by synchrotron radiation VUV light. Significant spectra overlap between the Mn2+ 6A1g→(4Eg, 4A1g) excitation (centered at 412nm) and the Pr3+ 1S0→(1I6, 3PJ) emission (410nm) provided the possibility of energy transfer from Pr3+ to Mn2+. In the LaMgB5O10:Pr3+, Mn2+ samples investigated, the expected energy transfer process was observed as comparing the emission spectra of LaMgB5O10:Pr3+, Mn2+ samples with that of the LaMgB5O10:Mn2+. The shorter decay time of the 1S0→(1I6, 3PJ) transition in the co-doped samples was also an evidence of energy transfer from Pr3+ to Mn2+. By analyzing the energy transfer process, it was found that the energy transfer process in LaMgB5O10:Pr3+, Mn2+ was likely of resonant energy transfer and the re-absorption process can be excluded. The critical distances of energy transfer based on the electric dipole–dipole interaction and electric dipole–quadrupole interaction were calculated to be 4.78 and 9.46Å in LaMgB5O10:Pr3+, Mn2+, respectively, which are smaller than the mean distance of Pr3+ and Mn2+ (17Å) in the highest concentration-doped sample. The near neighboring Prrs formed in the LaMgB5O10 host is responsible for the energy transfer process. [Copyright &y& Elsevier]

Abstract: Luminescent properties of Pr3+ or Mn2+ singly doped and Pr3+, Mn2+ co-doped LaMgB5O10 are investigated by synchrotron radiation VUV light. When LaMgB5O10:Pr3+ is excited at185nm, the photon cascade emission between 4f levels of Pr3+ is observed. In the excitation spectra of LaMgB5O10:Mn2+ monitoring the 615nm emission of Mn2+, several excitation bands in a spectral range from 330 to 580nm are recorded, among which the most intense band is centered at 412nm (6A1g→4Eg–4A1g). This band has considerable spectra overlap with the 410nm emission (1S0→1I6) of Pr3+, which is favorable for energy transfer from Pr3+ to Mn2+. Such energy transfer is observed in the co-doped sample, converting the violet emission (410nm) of Pr3+ into the red emission (615nm) of Mn2+. The concentration dependence of transfer efficiency is also investigated. [Copyright &y& Elsevier]

The phosphors, fluorapatites M5(PO4)3F (M=Ca, Sr, Ba) activated with Dy3+ ions, were prepared by a high-temperature solid-state reaction technique. The VUV-UV excitation spectra and emission spectra under VUV/UV excitation were measured. The phosphors show broad and strong absorption near 172 nm and intensive emission with the chromaticity coordinates entering the white light region. Hence, the phosphors may be considered as suitable candidates for Hg-free lamps. [ABSTRACT FROM AUTHOR]

Abstract: Luminescence properties of LSO:Ce, including the excitation spectra in 130–370nm and the emission spectra in 350–500nm as well as decay times were studied by synchrotron radiation at different temperature between 79 and 295K. The temperature dependence of the VUV (178nm) excitation band was different from that of the UV (264, 296 and 364nm) ones of LSO:Ce luminescence (436nm). The former had no thermo-quenching and the latter thermo-quenching was evident for both single crystal and powder sample. Not only the excitation spectra, but also the VUV excited emission spectra showed a temperature dependent behavior. The difference can be ascribed to a different energy transfer process in the LSO:Ce material under VUV and UV excitation. When the temperature rises from 79 to 295K, the VUV excited luminescence decay times vary in the range of 27.6–32.4ns for single crystal and from 29.8 to 25.5ns for powder sample. [Copyright &y& Elsevier]

Abstract: A series of samples La2− x Pr x CaB10O19 were prepared by a solid-state reaction technique. The spectroscopic characteristics, including the steady-state excitation and emission spectra in the VUV–vis range, the luminescence decays and the concentration quenching are investigated. Two types of emission, photon cascade emission (PCE) and f–d emission were observed in the samples. The phenomena are interpreted in terms of different occupancies for Pr3+ in La3+ and Ca2+ sites. [Copyright &y& Elsevier]

Abstract: The intermediate role of Gd3+ in energy transfer to give light was investigated through spectroscopic study of Bi3+/Eu3+ doped YBO3/(Y,Gd)BO3 under VUV/UV excitation. All samples were prepared by solid-state reaction and the luminescent properties were characterized in a synchrotron radiation instrument. The results show that Gd3+ plays an intermediate “bridge” between the sensitizer of Bi3+ and the activator of Eu3+ in energy transfer in (Y,Gd)BO3:Bi3+,Eu3+ system. At the same, the mechanism for energy transfer was discussed, which is mainly through electric multipole interaction or exchange interaction. [Copyright &y& Elsevier]

Abstract: (Y0.99Bi0.01)BO3 phosphor was prepared and its luminescent properties were investigated using the synchrotron radiation instrument in this paper. Site-selective luminescence of Bi3+ in the YBO3 host was demonstrated by exciting/monitoring with different wavelengths at low temperature in this research. At the same time, the energy transfer between the centers of Bi3+ ions occupying different symmetric sites was observed. The excited energy levels of Bi3+ were identified through assigning the emission and excitation spectra. The paths and mechanism of energy transfer between the centers of Bi3+ occupying different symmetric sites were discussed finally. [Copyright &y& Elsevier]

Abstract: The temperature-dependent emission spectra of Pr3+-doped SrB4O7 were investigated from 20 to 300K under vacuum ultraviolet excitation. When the temperature was over 80K, the interconfigurational 4f15d1→4f2 and intraconfigurational 4f2→4f2 emissions could be observed simultaneously. The theoretical model describing thermal equilibrium of the energy levels was applied successfully to the system concerning the lowest-energy 4f5d state and 1S0 state of SrB4O7:Pr3+. In addition, the decay curves of Pr3+ emissions from 300 to 600K were also measured. The decay times of 4f5d emission and 1S0 emission were same for a certain temperature and became faster with increased temperatures, which further identified the validity of the model applied to the system. This paper clarified the nature of unusual temperature dependence of the emission spectra of Pr3+ in SrB4O7. [Copyright &y& Elsevier]

Abstract: The stilbene-3 doped lead–tin–fluorophosphate glasses were successfully prepared and the luminescence spectra obtained from VUV–UV synchrotron radiation were investigated. The emission peaked about 440nm from the undoped glass is observed at low temperature but quenches at room temperature. The doped glass exhibits strong characteristic emission of stilbenen-3 with 467 and 436nm Gaussian bands under ultraviolet 250–330nm excitation (characteristic excitation of stilbene-3) but weak emission under vacuum ultraviolet 190nm excitation (host excitation). It is suggested that the energy transfer from host to the stilbene-3 dye can occur but the efficiency is still fairly low. [Copyright &y& Elsevier]

Abstract: RE3+-activated α- and β-CaAl2B2O7 (RE=Tb, Ce) were synthesized with the method of high-temperature solid-state reaction. Their VUV excitation and VUV-excited emission spectra are measured and discussed in the present article. The charge transfer band of Tb3+ and Ce3+ is respectively calculated to be at 151±2 and 159±3nm. All the samples show an activator-independent excitation peak at about 175nm and an emission peak at 350–360nm ascribed to the host absorption and emission band, respectively. [Copyright &y& Elsevier]

Abstract: VUV-Vis range spectroscopic characteristics from Pr3+ ions in CaMgAl14O23, LaF3, YBO3, YPO4 and LaF3 nanocrystals doped oxyfluoride glass ceramics are presented. Upon excitation into the 4f5d states, the emission spectra of Pr3+ correlated with the relative positions of the 1S0 state and the lowest 4f5d states. For Pr3+ ions in CaMgAl14O23 and LaF3, the lowest 4f5d state lies above the 1S0 state. So an efficient photon cascade emission occurred due to a two-step intraconfigurational 4f2→4f2 transition. For Pr3+ ions in YBO3 and YPO4, the lowest 4f5d state lies below the 1S0 state. The UV emission of 4f5d→4f2 transition was observed. Both types of Pr3+ ions exist in the oxyfluoride glass containing LaF3 nanocrystals. The positions of the lowest 4f5d state of Pr3+ in different host lattices are given. [Copyright &y& Elsevier]

Abstract: LiYF4, NaYF4, KYF4 and LiLuF4 doped with Pr3+ were synthesized by hydrothermal technique. Vacuum ultraviolet excitation and emission properties were investigated at 20K. A new type of photon cascade emission was observed in LiYF4:Pr3+ and LiLuF4:Pr3+, i.e. a first-step 4f5d→4f2 emission followed by a second 4f2→4f2 emission. In addition, the internal quantum efficiency of Pr3+ in NaYF4 and KYF4 within visible range was proved to be larger than unity using the branching ratios data corrected by the emission spectra of YF3:Pr3+. [Copyright &y& Elsevier]