The 1S0 emission from the minor site of Pr3+ in (Ba,La)F2:Pr

In this paper we present and discuss results of detailed spectroscopy studies of Pr³⁺ luminescence from the (Ba,La)F₂:0.2 m%Pr crystals under UV and VUV synchrotron excitation.We have measured time resolved emissions from the minor site Pr³⁺ in (Ba,La)F₂:Pr at 10 and 300 K. The spectra clearly show the ¹S₀ emission from the Pr³⁺ ions in some low symmetry Pr-sites (we designate them La-sites) previously identified in higher concentration (0.3 m%Pr and more) crystals. However most of emission from the Pr activated (Ba,La)F₂ crystals originates in Pr³⁺ ions in other sites which produce an efficient d-f emission. As demonstrated by excitation spectra, the emission from some of these sites (denoted as Ba-sites) closely resembles the d-f emission from BaF₂.The La-site, time resolved and long delay emission spectra are dominated by hypersensitive transitions from the ¹S₀ and ³P₀ levels to lower energy levels of the 4f² configurations. Only these transitions contribute to the photon cascade emission desired for some mercury free phosphor applications.     

Tysonite structure and crystal-field analysis of the Pr3+ ion in PrF3

The quadratic Zeeman effect of the Pr³⁺ ion in PrF₃ and a Raman spectroscopic investigation of the optical phonons in LaF₃ have been used to test the crystal structures proposed in the past for tysonite. We find that the twinned structure is consistent with all available experimental results. A crystal field Hamiltonian parametrized in monoclinic symmetry was used to describe the observed crystal field splittings of Pr³⁺ in PrF₃. Our best parameter set gave a r.m.s.-deviation of 12 cm^–1. As a test for the eigenfunctions the quadratic Zeeman shifts are calculated and compared with the experimental results.     

Efficient Continuous Wave-laser emission of Pr3+-doped fluorides at room temperature

We report, to our knowledge for the first time, Continuous Wave (CW) laser emission at room temperature of Pr:LiYF₄ (Pr.YLF) at six wavelengths: 522, 545, 607, 639.5, 720 and 907.4 nm. The pump source was an argon-ion laser tuned to a wavelength of = 457.9 nm. The maximum output powers at 522 nm (³P_i ³H₅) and 639.5 nm (³P₀ ³F₂) were 144 and 266 mW, respectively. We also observed CW laser action of Pr:GdLiF₄ (Pr: GLF) at = 639 nm and of Pr:KYF₄ (Pr: KYF) at = 642.5 nm.     

Stimulated emission and laser action of Pr3+-doped YA1O3

Groundstate absorption, fluorescence, excited-state absorption, and stimulated emission of Pr:YA1O₃ were measured in dependence on the polarization. The results reflect the anisotropy of the host lattice. Especially the polarized spectra of the stimulated emission fit very well with the laser data of this material. Seven cw laser transitions in the visible spectral range obtained so far in Pr:YA1O₃ with argon-ion laser pumping were identified in the spectra of the stimulated emission. In addition, two infrared cw laser transitions were realized. The best results were achieved for the³ P ₀³ F ₄ laser transition at 746.9 nm with a maximum slope efficiency of 24.6%, a maximum output power of 49.6 mW, and a laser threshold of 25 mW.     

Luminescence of Ca(NbO3)2:Pr3+: Pr3+ and self-trapped exciton emission

Photoluminescence and time resolved photoluminescence spectra of Ca(NbO₃)₂ doped with Pr³⁺, excited under 37,000 cm^?1 (270 nm), obtained at high hydrostatic pressure up to 20 kbar applied in a sapphire anvil cells, are presented. At ambient conditions, the emission spectrum obtained in the time interval 0–1 μs is dominated by spin allowed transitions from the ³P₀ state. The luminescence related to transitions from ¹D₂, characterized by a decay time equal to 33 μs, is observed when one excites directly the Pr³⁺ ion with 30,770 cm^?1 (325 nm) wavelength. The introduction of Pr³⁺ impurities in Ca(NbO₃)₂ does not quench the self-trapped exciton (STE) luminescence. This luminescence, peaking at 20,000 cm^?1 (500 nm), having a decay time of 61 ± 1 μs, still occurs when the crystal is excited with a wavelength of 37,000 cm^?1 (270 nm) or shorter. Under such excitation a fraction of the STE luminescence is reabsorbed by Pr³⁺ ions; in this case the emission lifetime of the ¹D₂ → ³H₄ transition of Pr³⁺ is 64 ± 3 μs. This effect is stable also at high pressure.     

Intense orange emission in Pr3+ doped lead phosphate glass

Spectroscopic properties of one mol% Pr₂O₃ embedded in 40%PbO–60%P₂O₅ glass have been investigated at room temperature. From the absorption spectra energy levels of the observed bands are assigned. Using free ion Hamiltonian theoretical values of energy of 13 multiplets of Pr³⁺ are calculated. Judd–Ofelt intensity parameters have been estimated by including and excluding the hypersensitive transition (³H₄→³P₂). The best set of Judd–Ofelt parameters are obtained by omitting ³H₄→³P₂ transition from the calculation. These parameters are used to evaluate the important laser parameters for various emission lines. Our investigation reveals that the present glass may be utilized as a laser active medium corresponding to ³P₀→³H₄ and ¹D₂→³H₄ transitions respectively, for 484.6 nm (blue) and 599.5 nm (strong orange) emissions. Indirect and direct optical band gap energies of Pr³⁺ doped lead phosphate glass matrix have also been reported.     

Dependence of cross-relaxation on temperature and concentration from the 1D2 level of Pr3+ in YPO4

We report on the role of cross-relaxation in the decay of the ¹D₂ level of trivalent Pr in YPO₄ in crystals with Pr concentrations of 0.1%, 1%, 2%, and 5%. We have found that the ¹D₂ level decay is purely radiative in the low-doped system. As the Pr concentration is increased, the ¹D₂ luminescence is quenched due to a cross-relaxation energy transfer between two Pr ions. The temporal behavior of the ¹D₂ luminescence following pulsed excitation has been monitored in each sample at temperatures between 30 K and 300 K, and all decay curves were fit to the Yokota–Tanimoto model. The decay times decrease as temperature increases, due to an increase in both the radiative rate and the energy transfer rate with temperature. There is little evidence of diffusion at any temperature, even in the more concentrated samples. We have also fit the decay curves using the LumiTrans computer simulation. A comparison of the fits to the decay curves of the two methods is presented.     

Observation of the 1S0-->3P0 clock transition in 27Al+

We report, for the first time, laser spectroscopy of the 1S0-->3P0 clock transition in 27Al+. A single aluminum ion and a single beryllium ion are simultaneously confined in a linear Paul trap, coupled by their mutual Coulomb repulsion. This coupling allows the beryllium ion to sympathetically cool the aluminum ion and also enables transfer of the aluminum's electronic state to the beryllium's hyperfine state, which can be measured with high fidelity. These techniques are applied to measure the clock transition frequency nu=1,121,015,393,207,851(6) Hz. They are also used to measure the lifetime of the metastable clock state tau=20.6+/-1.4 s, the ground state 1S0 g factor gS=-0.000,792,48(14), and the excited state 3P0 g factor gP=-0.001,976,86(21), in units of the Bohr magneton.     

UV emission properties of highly Pr3+-doped YAG epitaxial waveguides

In this work we present and discuss the dependence of ultraviolet (UV) photoluminescence of praseodymium ion (Pr³⁺):YAG crystalline waveguides, produced by liquid phase epitaxy, on activator concentration. Praseodymium level influence on UV fluorescence intensity, transition linewidth and dynamics was carefully investigated in order to better understand the nature of processes shaping both the interconfigurational d–f emission and intraconfigurational f–f emissions starting from the ³P₀ excited state. The pathways and the role of interconfiguration cross-relaxation in quenching of the UV 4f5d emission are analyzed.     

Laser excitation of Pr3+ sites in ThCl4:Pr3+

Use of site selection spectroscopic techniques combined with low temperature absorption spectral studies has enabled the identification and characterization of ten optically important charge-compensated crystallographic sites for Pr³⁺ in the β-ThCl₄:Pr³⁺ system. Fluorescence decay time measurements, variation of site distribution with dopant concentration and fluorescence spectra were used to characterize the sites. Distant charge compensation is found to be one of the dominant modes of charge compensation of Pr³⁺ in ThCl₄, and its predominance over other sites increases as Pr³⁺ concentration decreases. The sinusoidal distortion of the crystal field symmetry around Pr³⁺ in the incommensurate phase of β-ThCl₄ is believed to be mainly responsible for the splitting and continuous shift in fluorescence spectral lines which occur when ³P₀→³F₂ fluorescence scans are made with excitation at different points on the ³P₀←³H₄ absorption line belonging to different sites.     

ZBLAN玻璃中Pr3+掺杂离子3P0和1D2能级的发光特性和寿命

对ZBLAN氟锆酸盐玻璃中Pr³⁺掺杂离子³P₀和¹D₂能级的寿命和发光特性进行了较详细的光谱学研究。首先测量了两种掺杂浓度(质量分数分别为1×10^-3,5×10^-3)的Pr³⁺:ZBLAN玻璃的吸收光谱,然后运用时间分辨激光光谱技术测量了³P₀和¹D₂能级在激光单光子共振激发下的荧光发射谱和能级寿命。将不同荧光发射谱带的强度和文献报道的Judd Ofelt理论计算辐射跃迁几率数值做了比较分析,证明了文献中理论计算结果的可靠性。由于浓度猝灭效应,在相同的激发条件下,掺杂浓度为1×10^-3样品的荧光发射强度明显大于5×10^-3样品的荧光发射强度。但是从我们的测量结果看,掺杂浓度对³P₀和¹D₂ 的能级寿命值无显著影响。掺杂浓度为1×10^-3时,Pr³⁺离子³P₀和¹D₂能级的寿命值分别为46,322μ_s。     

Energy transfer from Tm3+ to Pr3+ in barium borate glass

The system of Tm³⁺ and Pr³⁺ in barium borate glass is investigated for finding out the mechanism of nonradiative energy transfer at room temperature. The various constants for this system relevant to the energy transfer are also calculated.     

Temperature-dependent segregation of Pr3+ impurity ions in Y2SiO5:Pr3+ and YPO4:Pr3+ nanocrystals

Stationary and time-resolved spectroscopic methods are used to show that the impurity ions in Y₂SiO₅:Pr³⁺ and YPO₄:Pr³⁺ nanocrystals are distributed nonuniformly. This nonuniform distribution is found to be caused by the temperature-dependent segregation of Pr³⁺ ions near the surface of a nanocrystal. The motion of the activator ions from the bulk of a nanocrystal to the near-surface layer is traced when the activator concentration and the heat-treatment parameters are varied over wide ranges, and the main parameters of this effect (impurity redistribution intensity and time, diffusion coefficient) are estimated.     

GdBO3：Pr3+，Yb3+中Pr3+到Yb3+的能量传递及发光性质

采用高温固相法制备了一系列单掺或双掺Pr3+和Yb3+的GdBO3材料,分别测试分析了材料的物相结构和发光性质。在446 nm蓝光( Pr3+：3 H4→3 P2)激发下,检测到Yb3+的近红外特征发射,表明样品中存在Pr3+到Yb3+的能量传递。 Pr3+的掺杂浓度一定时,样品的发光会随着Yb3+掺杂浓度的改变而发生变化。通过对比不同掺杂情况下Pr3+：3 P0能级的衰减曲线,发现随着Yb3+的掺杂浓度的增加,该能级的荧光寿命不断缩短;同时利用不同条件下的衰减特性计算得出不同 Yb3+掺杂浓度样品的能量传递效率。用 Inokuti-Hirayama模型分析表明Pr3+-Yb3+能量传递类型为偶极子-偶极子相互作用。     

3+1维格点规范理论0++和0－－胶球质量

在哈密顿形式下,把无规相近似方法从(2+1)维SU(2)格点规范场推广到3+1维SU(3)格点规范场,利用这种改进的耦合集团展开方法计算3+1维SU(3)的真空波函数和0^－－与0⁺⁺胶球质量之比,得到令人满意的结果:γ=m(0－－)m(0++)=1.8578±0.0506.     

Luminescence properties of K1/2Bi1/2TiO3:Pr3+ and Na1/2Bi1/2TiO3:Pr3+

The luminescence properties of K(1/2)Bi(1/2)TiO(3):Pr(3+) and Na(1/2)Bi(1/2)TiO(3):Pr(3+) powders are investigated in the temperature range 10-600 K. The experimental data are interpreted on the basis of metal-to-metal charge transfer processes and by considering Bi(3+)-to-Pr(3+) sensitization effects.     

偏硅酸钙中Pr3+的4f5d态的光谱特性及Pr3+→Gd3+的能量传递

合成了高效发射UV光的CaSiO3:Pr^3 新型荧光体，研究了室温下Pr^3 的4f5d态的发射和激发光谱，Pr^3 的4f5d态的最低子能级向4f^2组态的^3H4，^3H6和^1G4能级跃迁产生UV发射，并不伴随有4f-4f能级跃迁的可见光发射。Pr^3 的浓度猝灭是由于辐射和无辐射能量传递造成的，同时，在CaSiO3中，存在Pr^3 →Cd^3 的能量传递，探讨了其能量传递特性。