Energy Levels Of Pr3 Research Articles

Optical properties of Praseodymium (Pr3+) doped bismuth boro-tellurite glasses containing CdSe nanoparticles

Adding TeO2 and growing nanoparticles of CdSe can significantly affect the optical properties of Pr3+ ions doped in bismuth borate glasses. We used a modified Judd-Ofelt analysis to obtain the intensity parameters from the optical absorption spectra. Adding TeO2 leads to an increase in the covalency of the Pr-O bond. However, the presence of CdSe nanoparticles makes Pr-O bond less covalent. Optical band gap shows a considerable decrease when nanoparticles are present. Phonon side band analysis suggests that energy levels of Pr3+ responsible for the intense red emission are populated through a cross-relaxation mechanism instead of multiphonon decay process. The blue transition of Pr3+ shows significant enhancement for the stimulated emission cross-section when CdSe nanoparticles are present. Chromaticity analysis identifies the overall light emissions from different glass samples with various standard sources. Our glass samples also possess high spectroscopic quality factors compared to similar systems doped with Pr3+ ions.

Insights into the Microstructures and Energy Levels of Pr3+-Doped YAlO3 Scintillating Crystals.

Trivalent praseodymium (Pr3+)-doped materials have been extensively used in high-resolution laser spectroscopy, owing to their outstanding conversion efficiencies of plentiful transitions in the visible laser region. However, to clarify the microstructure and energy transfer mechanism of Pr3+-doped host crystals is a challenging topic. In this work, the stable structures of Pr3+-doped yttrium orthoaluminate (YAlO3) have been widely searched based on the CALYPSO method. A novel monoclinic structure with the Pm group symmetry is successfully identified. The Pr3+ impurity can precisely occupy the Y3+ position and get incorporated into the YAlO3 (YAP) host crystal with a Pr3+ concentration of 6.25%. The result of the electronic band structure reveals a 3.62 eV band gap, which suggests a semiconductor character of YAP:Pr. Using our developed well-established parametrization matrix diagonalization (WEPMD) method, we have systematically analyzed the energy level scheme and proposed a set of newly improved parameters. Additionally, the energy transfer mechanism of YAP:Pr is clarified by deciphering the numerical electric dipole and magnetic dipole transitions. The popular red emission at 653 nm is assigned to the transition 3P0 → 3F2, while the transition 3P0 → 3H4 with a large branching ratio is predicted to be a good laser channel. Many promising emission lines for laser actions are also obtained in the visible light region. Our results not only provide important insights into the energy transfer mechanisms of rare-earth ion-doped materials but also pave the way for the implementation of new types of laser devices.

Fabrication and characterization of luminescent Pr3+ doped fluorapatite nanocrystals as bioimaging contrast agents

Fluorapatite doped with rare-earth elements has a wide-range of biomedical applications. Here, a new type of fluorapatite nanocrystals doped with praseodymium (FAP-Pr) with excitation-emission profiles in visible part of the spectrum is fabricated. Energy levels of Pr3+ activator ion contain metastable multiplet states that offer the possibility of efficient multicolor emission lines in FAP nanocrystals. Three types of FAP-Pr nanocrystals with 0.1%, 0.5% and 1% atomic percent of Pr3+ (along with the undoped FAP control sample) are studied. Their novel chemical production method is described, the FAP-Pr nanocrystals structure, biocompatibility and the suitability for cell imaging are analyzed. Physicochemical characterization confirms crystals down to nanometer size. In addition, quantum-chemical calculation predicts that Pr3+ ions are incorporated into the FAP crystal lattice at Ca2 (6 h) sites. In vitro viability results shows that FAP-Pr nanocrystals are nontoxic to live cells. Additionally, the cell uptake of the FAP-Pr nanocrystals is studied using fluorescence-based widefield and confocal microscopy. The nanocrystals show characteristic green emission at 545 nm (3P0→3H5 transition of Pr3+ ion) and orange emission at 600 nm (1D2→3H4), which we use to discriminate from cell autofluorescence background. Orthogonal projections across 3D confocal stacks show that the nanocrystals are able to enter the cells positioning themselves within the cytoplasm. Overall, the new FAP-Pr nanocrystals are biocompatible and of the tested types, the 0.5% Pr3+ doped nanocrystals show the highest promise as a tracking nanoparticle probe for bioimaging applications.

Spectroscopic characterization of orthorhombic δ-BiB3O6 phase nonlinear single crystal doped with Pr3+ ions

The spectroscopic properties of 1 at% Pr3+ doped δ-BiB3O6 (BIBO) single crystal were investigated. The absorption, emission and excitation spectra were studied at low (10 K) and at room temperature, with the emission and absorption spectra showing clear polarization dependence. The strongest observed luminescence band corresponds to the 1D2 → 3H4 transition at 610 nm. Energy levels of Pr3+ in δ-BIBO host were assigned on the basis of low temperature absorption and emission measurements. The number of crystal field levels derived implies that Pr3+ ions are located in one crystal site in the BIBO host. Decay time of the praseodymium 3P0 emission was unusually short and the 1D2 decay was non-exponential. The modified Judd-Ofelt intensity formalism was used to analyze the experimental data. The Ωλ parameters, branching ratios and electric dipole transition probabilities were determined. The stimulated emission cross-sections σ for the 5D0 → 3HJ transitions were also evaluated in this system.

Near ultraviolet and visible-to-near-infrared spectral converting properties and energy transfer mechanism of Sr_2SiO_4:Ce^3+, Pr^3+ phosphor

A visible-to-near-infrared spectral converting phosphor Ce3+, Pr3+ co-doped Sr2SiO4 was synthesized by a solid-state reaction, and was developed as a potential solar spectral convertor for Si solar cells. The diffuse reflection, photoluminescence excitation and emission spectra at room temperature and at 3K were investigated. The visible and near infrared luminescent properties and energy levels of Pr3+ were investigated in detail. These results demonstrate that the absorption of Pr3+ was greatly broaden and enhanced in UV-Vis through efficient energy feeding by allowed 4f-5d absorption of Ce3+. The energy transfer mechanism including downshift and quantum cutting process is also proposed.

Investigation on the magnetic and magnetocaloric properties of PrNi2

The magnetic properties of some magnetic materials are influenced by the exchange interaction between magnetic ions and the spin fluctuations of magnetic ions. By use of the exchange interaction-effective field including the spin fluctuations of magnetic ions Hm= n0(1+γ T +β eω T)M, the Zeeman splitting of crystal field energy levels of Pr3+ ions in PrNi2 and the variation of the magnetic moments with the applied field in a temperature range of 3.8 K≤ T ≤ 30 K are calculated. The thermal variation of the reciprocal susceptibility of Pr3+ ions is calculated as well for the applied magnetic field H=5000 Oe. The calculated results are in good agreement with the experimental data. The magnetic entropy changes are obtained theoretically in a magnetic field range of 0H<50000 Oe, and the results are similar to those reported in the literature. It is indicated that the exchange interaction-effective field containing the spin fluctuations is applicable not only to the ferrimagnetic crystals, but also to the paramagnets.

Theoretical Study of Energy Levels Splitting of Praseodymium-Doped Trichloride

A 91×91 complete energy matrix of 4f2configuration ion Pr3+in triagonal crystal fieldC3hhas been constructed based upon the combination of Racahs irreducible tensor with Slaters wavefunctions. Thus, the Stark energy levels of Pr3+in trichlorides LaCl3have been calculated. The calculation result shows that the complete energy matrix method is effective to analyze the energy levels splitting of the doped entity by rare earth ions. We also know that the consideration to the sixth-order crystal field parameters is indispensable and the ionic radius of the replaced ion will play an important role in the energy levels splitting of the doped systems.

On spectroscopic properties of the KYb(WO4)2:Pr3+ crystal

Spectroscopic properties of Pr3+ doped KYb(WO4)2 single crystals were investigated. The crystal lattice parameters were determined. Energy levels of Pr3+ in KYb(WO4)2 were assigned. The absorption, emission, excitation, time-resolved emission and excitation spectra were measured at low (10 K) and at room temperature. Decay times of the praseodymium emissions are non-exponential and unusually short. Site selection spectroscopy evidences several different Pr3+ sites. The Judd-Ofelt intensity model was used to analyse the experimental data. The Ω λ parameters, branching ratio and electric dipole transition probabilities were determined.

Energy levels of Pr3+:GdOCl under pressure

Excitation and luminescence spectra of Pr3+ in GdOCl weremeasured in the spectral range from 11 000 cm-1 to22 500 cm-1. At ambient pressure a total of 54 spectrallines were observed. Some of these lines cannot be explained bytransitions between crystal-field levels of the regular Pr3+ site in GdOCl. Possible explanations of these lines arediscussed. Under pressure up to 16 GPa, all lines exhibit ared-shift, from which a part of the energy level scheme of the4f2 configuration could be derived. From the 34 levels atambient pressure, 31 could also be obtained under pressure. Theenergy level scheme is described in terms of the free-ion parameters(F k, α, β, γ, ζ, Mk, P k) andcrystal-field parameters (B 20, B 40, B 44, B 60,B 66). The variations of these parameters under pressure weredetermined. Surprisingly, the crystal-field strength, calculatedfrom the crystal-field parameters, first shows a slight decreasewith increasing pressure.

Effect of pressure and crystal structure on energy levels of Pr3+ in LaCl3.

The fluorescence of ${\mathrm{Pr}}^{3+}$ in ${\mathrm{LaCl}}_{3}$ as well as the single-crystal x-ray diffraction of ${\mathrm{LaCl}}_{3}$ under pressure have been studied in order to determine the dependence of the energy levels of ${\mathrm{Pr}}^{3+}$ in ${\mathrm{LaCl}}_{3}$ on the host-lattice structure. An analysis of this dependence is presented up to about 8 GPa. In this pressure range the Slater parameters ${F}_{2}$, ${F}_{4}$, and ${F}_{6}$ show a decrease of 1.2(2)%, 0.6(3)%, and 0.7(9)%, respectively. The spin-orbit coupling parameter ${\ensuremath{\zeta}}_{4f}$ decreases by 0.3(2)%. The various crystal-field parameters show distinctively different behavior: (1) \ensuremath{\Vert}${A}_{60}$〈${r}^{6}$〉\ensuremath{\Vert} and ${A}_{66}$〈${r}^{6}$〉 both increase with pressure, (2) \ensuremath{\Vert}${A}_{40}$〈${r}^{4}$〉\ensuremath{\Vert} decreases with pressure, and (3) ${A}_{20}$〈${r}^{2}$〉 goes through a minimum at about 5(1) GPa.It is shown that the present theoretical models for the variation of the ``free-ion'' parameters in crystals cannot account consistently for the observed shifts. An analysis of the high-pressure behavior of crystal-field parameters using superposition and angular overlap models is shown to be successful for ${A}_{60}$〈${r}^{6}$〉, ${A}_{66}$〈${r}^{6}$〉, and ${A}_{40}$〈${r}^{4}$〉. However, the same analysis for ${A}_{20}$〈${r}^{2}$〉 breaks down, unless one assumes a nonlinear dependence for the intrinsic parameter A${\ifmmode\bar\else\textasciimacron\fi{}}_{2}$(R) on the internuclear distance R with a maximum in the experimental range. The present angular-overlap model analysis of the crystal fields, as well as a comparison with the ab initio calculations for intrinsic parameters A${\ifmmode\bar\else\textasciimacron\fi{}}_{4}$(R) and A${\ifmmode\bar\else\textasciimacron\fi{}}_{6}$(R) indicate that the ligand contributions reproduce fairly well the variations of these two parameters. The peculiar behavior of the ${A}_{20}$〈${r}^{2}$〉 under pressure, however, still needs an explanation. The local distortions around the ${\mathrm{Pr}}^{3+}$ impurity has been estimated from a comparison of the structural and spectroscopic data for both ${\mathrm{Pr}}^{3+}$ in ${\mathrm{LaCl}}_{3}$ under pressure and ${\mathrm{Pr}}^{3+}$ in isostructural lanthanide trichloride host lattices at ambient pressure. It is shown that the largest local distortions of about 2% occur along the local c axis. Some fluorescence anomalies observed beyond 8-GPa-pressure region are also presented.

ChemInform Abstract: Energy Levels of Pr3+ in the Modulated Incommensurate Structure of ThCl4

ChemInform Abstract: Energy Levels of Pr3+ in the Modulated Incommensurate Structure of ThCl₄

Spectrum and energy levels of Pr3+ in ThBr4

The strong features in the absorption spectrum and the laser excited fluorescence spectrum have been interpreted as arising from levels of Pr3+ in the D2d symmetry site of ThBr4. 43 energy levels have been fitted to the parameters with an rms deviation of 61 cm−1. The values of the crystal field parameters are B20=260.0, B40=−644.2, B44=929.2, B60=1089.0 , and B64=240.6 cm−1. The presence of other crystal symmetry sites is observed.

Identification of Energy Levels ofPr3+in LaCl3

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The absorption spectra and energy levels of Pr3+ in a CeF3 single crystal

The absorption spectra and energy levels of Pr3+ in a CeF3 single crystal

Optical absorption spectrum and energy levels of Pr3+ in Pr(ReO4)3 � 4 H2O single crystals

Optical absorption spectrum and energy levels of Pr3+ in Pr(ReO4)3 � 4 H2O single crystals

Energy Levels of Er3+ and Pr3+ in Hexagonal LaBr3

The spectra of Er3+ in LaBr3 are similar to, but not the same as, those of Er3+ in LaCl3. The Stark splittings of the Y and Z groups are used to determine the crystalline-field parameters for LaBr3, which are B20=117, B40=−39.6, B60=−19.2, and B66=212 cm−1. These are significantly different from those of LaCl3. The centers of gravity of the excited Stark groups are higher in LaCl3 than in LaBr3, and this shift increases with increasing wavenumber. Spectra and energy levels of Pr3+ in LaBr3 are also given.

Energy Levels of Pr3+ in LaF3

The absorption and fluorescence spectra of Pr3+(4f2) in LaF3 have been investigated in the spectral region 4000 to 60 000 Å. From the present study and previously published data, all of the 2J+1 Stark components of the 3H4,5,6, 3F2,3,4, 1G4, 1D2, 3P0,2, levels are identified. By means of a least-squares method, we have calculated the Slater and spin—orbit parameters that give a theoretical free-ion spectrum in close agreement with the observed spectrum of Pr3+(4f2) in LaF3 crystals. When the electrostatic interaction between 4f2 and 5d2 electronic configurations is taken into account, the average deviation between the calculated and the observed spectrum is 58 cm−1. The values of the parameters giving the best fit are F2=312.7 cm−1, F4=50.99 cm−1, F6=4.778 cm−1, and ζ=757.0 cm−1.