Luminescence Of Nd3 Research Articles

Lanthanide(III) complexes of N4O4 Schiff base macrocycle: Luminescence and formation of heterodinuclear d–f complexes

The new macrocyclic Schiff base lanthanide(III) complexes of the formula [Ln(H4L)Cl3]·nH2O (Ln=Pr(III), Nd(III), Sm(III), Gd(III), Dy(III), Ho(III), Er(III), Tm(III), Yb(III) and Lu(III)) have been synthesized in the template condensation of 1,3-diamino-2-hydroxypropane and 2,6-diformyl-4-methylphenol in the presence of the appropriate Ln(III) chlorides. The obtained compounds have been characterized in solution by NMR spectroscopy, and the 1H and 13C NMR spectra of [Pr(H4L)Cl3]·H2O, [Nd(H4L)Cl3]·H2O, [Sm(H4L)Cl3]·H2O and [Yb(H4L)Cl3]·4H2O complexes have been assigned on the basis of COSY, NOESY and HMQC techniques. The analysis of isotropic shifts of the paramagnetic Ln(III) derivatives indicate the unsymmetrical coordination of the lanthanide(III) ions within the macrocyclic ligand H4L. 1H NMR spectroscopy has also been used to follow transformation of the [Ln(H4L)]3+ complexes into heterodinuclear derivatives, [LnCo(H2L)]3+ and [LnCo(HL)]2+. Emission and excitation spectra as well as luminescence decay time measurements (at 293 and 77K) were used to characterize the photophysical properties of the mononuclear Eu(III), Gd(III) and Yb(III) [Ln(H4L)Cl3]·nH2O complexes in solid-state. Energy transfer from the ligand to the Yb(III) ions has been proved at both room temperature and 77K. The f–f luminescence of Nd(III) and Er(III) was not observed neither by the excitation through the ligand (1π–1π∗) nor the lanthanide ion absorption transitions both at 293 and 77K. In the case of Eu(III) complex the energy transfer only occurs at 77K, while at room temperature a thermally activated back energy transfer process from 5D0 Eu(III) excited state to the ligand triplet states has been proposed. The 4f–4f emission spectrum of Eu(III) in a low site symmetry with the dominating 5D0→7F4 transition has been demonstrated for the first time.

5d-4f luminescence of Nd3+, Gd3+, Er3+, Tm3+, and Ho3+ ions in crystals of alkaline earth fluorides

The vacuum ultraviolet emission spectra of alkaline-earth fluoride (CaF2, SrF2, BaF2) crystals with rare earth impurity ions (Nd, Gd, Er, Tm, Ho) have been investigated. The main luminescence bands are described well by the transitions from the lowest excited 5d state to different 4f levels of rare earth ions.

VUV-UV-visible luminescence of Nd3+, Er3+ and Tm3+ and energy distribution in LiLuF4 single crystal host

It is the aim of this contribution to provide an overview of luminescence spectra and decay characteristics of Nd3+, Er3+ and Tm3+ centers in LiLuF4 single crystal including possible energy transfer mechanisms towards and away from the Nd3+ 5d excited state. Single crystal doped with the mentioned RE ions were prepared by micro-pulling-down technique. Excitation and emission spectra and fast decay kinetics in VUV spectral region are completed with radio-and photoluminescence spectra and decay kinetics in UV-visible region.

VUV-UV-visible luminescence of Nd3+, Er3+ and Tm3+ in LiLuF4 single crystal host

Abstract An overlook of absorption and luminescence characteristics of Nd3+, Er3+ and Tm3+ centers in LiLuF4 single crystal is provided. Single crystal doped with the mentioned RE ions were prepared by micro-pulling-down technique in the form of few cm long rods with the diameter of about 2 mm. Excitation and emission spectra and fast decay kinetics in VUV spectral region were measured at SUPERLUMI station at synchrotron DESY, Hamburg and characterization was further completed in UV-visible region at conventional spectrophotometers. Observed absorption and emission peaks are ascribed to the 5d–4f and 4f–4f optical transitions in the doped rare earth ions. Concentration dependence of the decay kinetics is discussed.

Up-conversion luminescence from Nd 3+ ions doped in NaBi(WO 4) 2 single crystal

The luminescence of Nd 3+-doped in NaBi(WO 4) 2 single crystal was investigated from 10 K to room temperature. The excitation source was a pulsed dye laser in resonance into the ( 4G 5/2+ 2G(1) 7/2) levels of Nd 3+ ions. Several blue emission bands in the up-conversion luminescence spectra corresponded to transitions from 2P 1/2 to 4I 9/2. Some violet bands corresponding to transitions of 4D 3/2 → ( 4I 9/2, 4I 11/2, 4I 13/2) were also observed. For comparison, the luminescence spectra and decay curves excited by the pulsed 355 nm laser were measured. In order to investigate up-conversion mechanisms, the decay behavior and the dependence of the up-conversion luminescence on laser powers were investigated. The temporal decay behavior of the up-conversion luminescence indicated that the two-photon excited state absorption of the Nd 3+ ions was the dominant mechanism in this crystal.

Near-infrared luminescence of Nd^3+ and Tm^3+ ions doped ZnO nanocrystals

Intense near-infrared luminescence of Nd(3+) and Tm(3+) ions in the region of 860-1550 nm were achieved in 10-15 nm wurtzite ZnO nanocrystals fabricated by a facile sol-gel process. The optical properties of Nd(3+) and Tm(3+) ions were investigated by using the steady-state and time-resolved laser spectroscopy. Due to the well-ordered crystal-field surroundings experienced by Nd(3+) and Tm(3+) ions, sharp and well resolved emission lines of Nd(3+) and Tm(3+) ions were identified at 4-300 K. Time-resolved luminescence and decay behaviors of the (4)F(3/2)-->(4)I(11/2) transition of Nd(3+) ions reveal the existence of multiple Nd(3+) sites in ZnO nanocrystals.

Host-Sensitized Luminescence of Nd3+and Sm3+Ions Incorporated in Anatase Titania Nanocrystals

A sol−gel solvothermal method was introduced to incorporate Nd3+ and Sm3+ ions into TiO2 nanoparticles. Intense and well-resolved emission lines from Nd3+ or Sm3+ ions were realized upon excitation above the TiO2 bandgap at room temperature. The sensitized emissions of Nd3+ or Sm3+ were found to be much more efficient than a direct excitation of lanthanide ions (Ln3+). Multiple site emissions of Nd3+ and Sm3+ were detected by means of site-selective spectroscopy at 10 K. Moreover, a possible host-to-Ln3+ sensitization mechanism was proposed.

Green, orange, and red upconversion luminescence in Nd 3+/Yb 3+: Cs 2NaGdCl 6 powders under 785 nm laser excitation

Nd 3+:Cs 2NaGdCl 6 and Nd 3+, Yb 3+:Cs 2NaGdCl 6 polycrystalline powder samples were prepared by Morss method E. Under 785 nm semiconductor laser pumping, the upconversion luminescence of Nd 3+ ions in Cs 2NaGdCl 6 was investigated at room temperature, and three upconversion emissions near 538 nm (Green), 603 nm (Orange), and 675 nm (Red) were observed and assigned to 4G 7/2→ 4I 9/2, ( 4G 7/2→ 4I 11/2; 4G 5/2→ 4I 9/2), and ( 4G 7/2→ 4I 13/2; 4G 5/2→ 4I 11/2), respectively. The dependences of these upconverted emissions on laser power and Nd 3+ ion concentration were investigated, to explore the upconversion mechanism. The effect of doping Yb 3+ ions on the upconversion luminescence of Nd 3+ in Cs 2NaGdCl 6 was also studied under 785 nm laser excitation. The energy transfer processes were discussed as the possible mechanism for the above upconversion emissions.

Study of the luminescence of Nd^3+:Y_2O_3 optical ceramic

Pulsed cathodoluminescence of Nd3+:Y2O3 ceramic synthesized from nanopowders obtained by laser evaporation of a solid target has been investigated in the 350-850-nm range. The samples were sintered in vacuum furnaces at temperatures of 1550-2050°C, but with different heating rates: 5K/min (first group) and 0.75K/min (second group). Strong luminescence bands of the Nd3+ ion showed up in the samples of the second group at λ≈425 and 457nm. A wide emission band at λ≈485nm of the intrinsic center predominates in the samples of the first group, while the luminescence bands of neodymium become weaker as the sintering temperature of the samples increases. It is shown that the appearance of the bands at λ≈425 and 457nm is associated with the presence in the ceramic of an impurity, most likely the monoclinic γ-Y2O3 phase, concentrated in micron-size regions along the edges and at the junction points of the crystals.

Effects of neodymium incorporation on the structural and luminescence properties of theYAl3(BO3)4–NdAl3(BO3)4 system

The luminescence of Nd3+ ions in NdxY1−xAl3(BO3)4 (Nd:YAB) single crystals has been investigated as a function of the neodymiumconcentration in order to evidence the relation between the structural and spectroscopicproperties in this nonlinear laser system. The analysis of the experimental data allowed usto individuate four different composition ranges. For moderate concentrations(x<0.2) the lattice parameters are nearly constant, and the emission spectra arise fromNd3+ ions in unperturbed crystal sites. For concentrations in the0.2<x<0.75 range the lattice parameters notably depend on the neodymium content, anda concomitant variation of the luminescence features is observed. In the0.75<x<0.9 range a hexagonal to monoclinic phase transition takes place: the structuraldisorder is evidenced well by the broadening of the emission lines and bydiscontinuities in the concentration behaviour of other indicators such asthe crystal-field strength, energy transfer parameters, etc. Finally, forx>0.9 the finalformation of the NdAl3(BO3)4 (NAB) monoclinic phase is complete, and a new local ordering aroundNd3+ is very evident in the spectral features.

The concentration dependence of luminescence of Nd:Y3Al5O12 nanoceramics

Abstract Transparent Nd:YAG ceramics composed of nanosized grains were fabricated by the low temperature high pressure (LTHP) sintering technique. The effect of concentration of ions on luminescence properties of Nd 3+ doped YAG nanoceramics and nanopowders was investigated. It was found that at room temperature the intensity ratio of 4 F 3/2 → 4 I 9/2 and 4 F 3/2 → 4 I 11/2 transitions in nanoceramics was strongly dependent on concentration of Nd 3+ . This behavior was not observed for the Nd:YAG nanopowders. The nature of such behavior was briefly discussed in terms of lowering the site symmetry of Nd 3+ ions with applied pressure.

Luminescence and excitation spectra of YAG:Nd 3+ excited by synchrotron radiation

The low-temperature 4f 25d→4f 3 fast emission of Nd 3+ from YAG:Nd 3+ has been studied under excitation by synchrotron radiation. Additionally, 4f 3→4f 3 luminescence of Nd 3+ has been observed and assigned to transitions from the 2F(2) 5/2 and 4F 3/2 multiplet terms. The observed experimental spectra of Nd 3+ d–f emission and f–d excitation are well simulated by crystal-field calculations.

Calix[4]azacrowns as Novel Molecular Scaffolds for the Generation of Visible and Near-Infrared Lanthanide Luminescence

Two calix[4]azacrowns, capped with two aminopolyamide bridges, were used as ligands for the complexation of lanthanide ions [Eu(III), Tb(III), Nd(III), Er(III), La(III)]. The formation of 1:2 and 1:1 complexes was observed, and stability constants, determined by UV absorption and fluorescence spectroscopy, were found to be generally on the order of log beta(11) approximately 5-6 and log beta(12) approximately 10. The structural changes of the ligands upon La(III) complexation were probed by 1H NMR spectroscopy. The two ligands were observed to have opposite fluorescence behaviors, namely, fluorescence enhancement (via blocking of photoinduced electron transfer from amine groups) or quenching (via lanthanide-chromophore interactions) upon metal ion complexation. Long-lived lanthanide luminescence was sensitized by excitation in the pi,pi band of the aromatic moieties of the ligands. The direct involvement of the antenna triplet state was demonstrated via quenching of the ligand phosphorescence by Tb(III). Generally, Eu(III) luminescence was weak (Phi(lum) </= 0.01%) and much shorter lived (tau(lum) = 0.36 ms) than the Tb(III) emission. The latter, on the other hand, reached lifetimes of up to 2.60 ms and quantum yields as high as 12% for one of the ligands. Water/deuterium oxide exchange experiments showed the presence of only one solvent molecule in the coordination sphere of the lanthanides. However, Eu(III) luminescence was efficiently quenched by NH oscillators and the presence of a ligand-to-metal charge transfer state. Near-infrared luminescence of Nd(III) was also generated by energy-transfer sensitization.

Optical Properties of Polymethyl Methacrylate Doped with Neodymium Chelates

The luminescence of Nd(DBM)3(H2O)2‐, Nd(DBM)3Phen‐, and Nd(DBM)3(TOPO)2‐doped polymethyl methacrylate (PMMA) was investigated under excitation at 17,100 cm−1 (4I9/2→4G7/2). The 4F3/2→4I11/2 transition of the Nd(DBM)3(TPPO)2‐doped PMMA showed the strongest intensity. In order to predict the radiative properties of Nd(DBM)3(TOPO)2‐doped PMMA, its absorption spectrum was measured and Judd‐Ofelt parameters (Ω2, Ω4, Ω6) were calculated. The values of the radiative lifetime and the emission cross‐section of 4F3/2→4I11/2 transition are comparable with those shown by glasses used in solid state laser applications. It can be concluded that Nd(DBM)3(TOPO)2‐doped PMMA is an efficient luminescent material.

Stable 8-Hydroxyquinolinate-Based Podates as Efficient Sensitizers of Lanthanide Near-Infrared Luminescence

New polydentate ligands (e.g., Tsox and TsoxMe) have been synthesized to take advantage of the chelating effect of bidentate 8-hydroxyquinolinate subunits connected to a N,N,N',N'-tetraaminopropyl-1,2-ethylenediamine framework and with the aim of sensitizing the NIR luminescence of Nd(III) and Yb(III) ions. Ten pK(a)'s have been determined and the interaction between the ligands and Ln(III) ions in dilute aqueous solution has been probed both by potentiometric and spectrophotometric titrations. These studies have been mostly performed with the Eu(III) ion, which is in the middle of the lanthanide series, and extended to other ions (La(III), Er(III), Lu(IIII)). Stable complexes with Ln(III) ions are formed (pLn in the range of 14-16), the four chromophoric units being coordinated to the metal center, exploiting the entropic effect generated by the anchor. The monometallic complexes [Ln(H(2)L)](3)(-) exist as the major species at physiological pH regardless of the lanthanide used. Lifetime determinations of the Nd((4)F(3/2)) and Yb((2)F(5/2)) excited levels in both H(2)O and D(2)O at buffered pH point to the absence of water molecules bound in the inner coordination sphere of the Ln(III). Photophysical properties of the free ligands and of their lanthanide complexes have been investigated in buffered aqueous solutions both at room temperature and 77 K. The low-energy triplet state makes energy transfers from the ligand to the metal ions possible; this leads to a sizable sensitization of the Nd(III)- or Yb(III)-centered luminescence ( = 0.02% and = 0.18%) for Tsox chelates. Methylation of the amide functions removes the quenching mechanism induced by the proximate N-H vibrations and increases both the lifetimes and quantum yields of the TsoxMe chelates ( = 0.04% and = 0.37%). In fact, TsoxMe yields one of the most luminescent Yb(III) compounds known in water, and this ligand appears to be suitable for the development of NIR probes for bioanalyses.

Upconversion luminescence and energy transfer in Nd 3+, Ho 3+:Cs 2NaGdCl 6

Nd 3+, Ho 3+:Cs 2NaGdCl 6 powder sample was synthesized by using Morss's method E, and its upconversion luminescence was presented and analyzed. Under 514.5 nm Ar + laser excitation, two upconversion emission bands, with peaks at 422 and 492 nm, respectively, were recorded. In order to know the upconversion mechanism, the upconversion luminescence of Nd 3+:Cs 2NaGdCl 6 was also obtained. In conclusion, the emission bands with peak at 422 and 492 nm were determinately concluded to be from Ho 3+ ions. The responsible upconversion mechanism was deduced to be successive energy transfer from Nd 3+ to Ho 3+ ions.

Ion beam luminescence of Nd:YAG

Luminescence recorded during ion beam implantation of Nd:YAG has proved valuable in sensing structural and local crystal field changes caused by waveguide fabrication in this laser material. The relative line intensities from Nd are sensitive to excitation rate and so the spectra differ strongly between H+ and H2+ excitation, with further changes in the examples using He+ and N+ ions. The overall intensities are reduced at lower temperatures, as well as showing variations in relative line patterns. Some suggestions of component lines and weak broad bands are offered in terms of trace rare earth and other impurities.

Luminescence of Nd3+ in proton or helium-implanted channel waveguides in Nd:YAG crystals

Abstract Positive index changes were induced by ion implantation in neodymium doped YAG, in strip areas written by means of a specific slit-based set up, allowing efficient channel waveguiding. Thick waveguides (10 μm) were in particular formed by using H + ions. Very similar neodymium IR emissions to the one of the bulk were recorded around 1.06 μm, for an excitation at 810 nm, in both kind of waveguides.

Spectroscopic studies of the population of high-energy levels of Nd3+-doped laser crystals upon intense pumping

The luminescence of Nd:YAG and Nd:YAP crystals excited by intense 808-nm radiation from laser diodes and the second (532 nm), third (354.7 nm), and fourth (266 nm) harmonics of a pulsed Nd:YAG laser is studied in the range from 380 to 650 nm. A number of intense luminescence lines are assigned to the transitions from the high 2F(2)5/2 level. A channel of the efficient population of this level upon simultaneous pumping a Nd:YAG crystal by a diode laser and the second harmonic of the Nd:YAG laser is found.

Low-temperature high-pressure spectroscopy of lanthanum lutetium gallium garnet crystals doped withCr3+andNd3+

Low-temperature luminescence measurements under high pressures in diamond-anvil cell of nonstoichiometric lanthanum lutetium gallium garnet (LLGG) doped with Cr 3 + ions and nonintentionally with Nd 3 + ions are reported.Three nonequivalent Cr 3 + centers were found in the crystal using this technique. The results also reveal information about the electronic structure of different Cr 3 + centers in those crystals. Cr 3 + ions in a LLGG crystal experience a very low crystal field strength. The energy differences between the 4 T 2 and 2 E levels are negative, and equal to about - 1100 cm - for two of those centers and about -1500 cm - 1 for the third one. The spectral results were corroborated by a theoretical analysis of the luminescence decay times as a function of pressure, which allowed one to establish the exact values of the crystal-field parameter Dq at ambient pressure for those centers. The crystal exhibits a large inhomogeneous broadening of the R lines, associated with nonstoichiometry. In addition to the Cr 3 + luminescence also luminescence of Nd 3 + ions was detected in the LLGG crystals. One of the Nd 3 + luminescence lines, associated with the 4 F 3 / 2 4 I 9 / 2 transition. is strongly dependent on pressure, with a pressure coefficient equal to 0.96′0.02 cm - 1 /kbar, which makes this system interesting as a pressure gauge in the infrared region.