Lanthanide-based laser-induced phosphorescence for spray diagnostics.

The combination of X-ray diffraction with EXAFS was employed to assess the coordination environment of lanthanide complexes in solutions. This method is based on the assumption that the local structure of lanthanide complexes in solution combines elements of the crystal structure of the complex in the solid state (single- or polycrystalline) and the elements of the local structure of a lanthanide salt, completely dissociated in the solvent (usually chlorides). The success of this approach is demonstrated with the lanthanide (III) 2,3,4,5,6-pentafluorobenzoate complexes, where the local structure in aqueous and methanol solutions were estimated. Moreover, the dissociation degree of the complexes in aqueous and methanol solutions was evaluated.

Solution and solid state structures of lanthanide complexes with polyaza polyacetic macrocyclic lingads: A comparison of NMR and X-Ray studies

Synthesis and infrared and fluorescence spectral properties of luminescent terbium and europium complexes with open-chain carboxylate crown ethers

In the present work surface thermometry using a method based on the spectroscopy of inorganic luminescent material has been applied in a full-size aircraft jet engine. The technique utilizes laser-induced emission from thermographic phosphors for, non-intrusive, remote temperature diagnostics in combustion applications with high sensitivity and accuracy. In the present application the laser-induced phosphorescence technique has proven its applicability even in the extremely harsh environment prevailing next to a jet engine operating at full load. The measurement object, Volvo RM12, is based on the General Electric F404 engine, from which it has been developed to meet single-engine operating criteria and achieve higher performance. A phosphor material having suitable temperature sensitivity in the expected temperature range was applied to the surface of interest on the flameholder of the engine afterburner. Phosphorescence radiation was generated using the forth harmonic (266 nm) from a pulsed Nd:YAG laser as an excitation source. The resulting signal was detected with a photo multiple tube (PMT). Phosphorescence lifetime decay curves were recorded at various load of the engine, including use of the afterburner. By analyzing the lifetime decay, the temperature data was acquired through implementation of a regression equation extracted from well-defined calibration measurements on the phosphor used.

Fluorescence and the relevant factors of organized molecular films of a series of atypical amphiphilic β-diketone rare earth complexes

Evaluation of parent and nano-encapsulated terbium(III) complex toward its photoluminescence properties, FS-DNA, BSA binding affinity, and biological applications

The lanthanide(III) complexes [Ln(LH2)(NO3)3] 1-11(La-Er), 15(Y) and [Ln(LH2)(NO3)2(H2O)](NO3) 12-14 (Tm-Lu) of the tetraiminodiphenolate macrocycle L2- have been prepared by the transmetallation reaction between [Pb(LH2)(NO3)2] and Ln(NO3)3.nH2O. In these compounds, the uncoordinated imino nitrogens are protonated and are hydrogen bonded to the phenolate oxygens. The X-ray crystal structures of the La (1), Ho (10) and Lu (14) compounds have been determined. Compounds 1 and 10, in which all the three nitrates are bound in bidentate fashion, are isostructural with distorted bicapped square antiprism geometry for the metal centre. In [Lu(LH2)(NO3)2(H2O)](NO3) 14, of the two metal bound nitrates one is bidentate and the other is unidentate, while the metal centre obtains a distorted square antiprism coordination environment. Proton NMR spectra of the paramagnetic lanthanide complexes have been studied in detail. Contributions of contact and pseudo-contact shifts to the lanthanide induced isotropic shifts (LIS) of the macrocycle protons have been separated and good agreement has been obtained between the calculated LIS values and the experimentally observed values. Analysis of the NMR data has led us to conclude that all the complexes in dimethyl sulfoxide solution attain similar configurations. The absorption and emission spectral characteristic of several compounds have been investigated. The complexes of samarium (5) and europium (6) on photoexcitation at 400 nm exhibit well-resolved luminescence spectra at 77 K both in the solid state and a methanol-ethanol (1 : 4) glassy matrix. For the terbium (8) and dysprosium (9) complexes, however, the observed luminescence peaks are less resolved and weak in intensity.

Preparation, crystal structure and optical spectroscopy of the rare earth complexes (RE 3+=Sm, Eu, Gd and Tb) with 2-thiopheneacetate anion

Although lanthanide complexes have distinct advantages for use as light-emitting materials, such as sharp emission bands and 100% quantum efficiency theoretically, their performance was far below what is expected. A new terbium complex was designed and synthesized. Devices using it as an emitter present satisfactory performance, with the highest brightness of 12 000 cd/m2 and power efficiency of 11.3 lm/W, which is nearly 1 order of magnitude higher than what was reported previously. Comparison with analogous complexes indicated that this result originated from the terbium complex's well-balanced charge-transport properties.

The results of our investigation on the sensitized luminescence properties of three Eu(III) β-diketonate complexes of the form [Eu(2)(fod)(6)(μ-bpm)], [Eu(fod)(3)(phen)] and [Eu(fod)(3)(bpy)] and 4f-4f absorption properties of their Er(III) analogues ( fod = anion of 6,6,7,7,8,8,8- heptafluoro-2,2-dimethyl-3,5-octanedione, bpm = 2,2'-bipyrimidine, phen = 1,10-phenanthroline and bpy = 2,2'-bipyridyl) in a series of non-aqueous solvents are presented. The Eu(III) complexes are highly luminescent and their luminescence properties (intensity and band shape) are sensitive to the changes in the inner coordination sphere of the Eu(III) ion. The luminescence intensity of the mononuclear complexes in pyridine is drastically decreased. The coordination structure of the complexes in pyridine is transformed into a more symmetrical one which results into a slow radiative rate of the emission from the complexes. The ancillary ligands, phen and bpy are found better co-sensitizers as compared to the bpm to sensitize Eu(III)-luminescence. The 4f-4f absorption properties (oscillator strength and band shape) of the Er(III) complexes demonstrate that (4)G(11/2) ← (4)I(11/2) and (2)H(11/2) ← (4)I(15/2) hypersensitive transitions of Er(III) are very sensitive in some coordinating solvents which reflects complex-solvent interaction in solution. The hypersensitive transitions of [Er(fod)(3)(phen)] remain unaffected in any of the solvents and this complex retains its bulk composition in solution. The erbium complexes as well as the Er(fod)(3) chelate are invaded by DMSO. This solvent enters the inner coordination sphere by replacing heterocyclic ligand and the complexes acquire similar structure [Er(fod)(3)(DMSO)(2)] in this solvent. The results reveal that the luminescence and absorption properties of lanthanide complexes in solution can be controlled by tuning the coordination structure through ancillary ligands and donor solvents. This work shall prove useful in designing new biological applications with such probes.

Binuclear rare earth complexes Ln2L3phen2 (LnIII = NdIII, SmIII, EuIII, TbIII, DyIII, YbIII and YIII) with bis-CAPh type ligand - tetramethyl N,N'-(2,2,3,3,4,4-hexafluoro-1,5-dioxopentane-1,5-diyl)bis(phosphoramidate) (H2L) and 1,10-phenanthroline (phen) were synthesized and characterized by elemental analysis, IR, NMR, absorption and luminescence spectroscopy. Luminescence measurements were performed for all the complexes in solid state and for the EuIII, TbIII and YIII complexes - in solution in DMSO as well. The effective energy transfer from organic ligands to LnIII ions strongly sensitizes the LnIII ions emission and under excitation by UV light, the complexes exhibited bright characteristic emission of lanthanide metal centers. It was found that the energy level of the ligands lowest triplet state in the complexes matches better to resonance level of EuIII rather than TbIII ion. Depending on temperature the emission decay times of solid europium and terbium complexes were in the range of 1.5-2.0ms. In solid state at room temperature the EuIII complex possess intense luminescence with very high intrinsic quantum yield 91% and decay time equal 1.88ms.

The solid-state, continuous-wave, frequency-doubled neodymium: yttrrium-aluminum-garnet (Nd:YAG) laser pumped by a diode laser has several advantages, including air cooling, higher electrical to optical efficiency ratios, portability, and the use of standard 110-V AC electrical service. The authors wanted to evaluate the use of the frequency-doubled Nd:YAG laser for peripheral iridotomy and to compare the tissue interactions of this laser with those of the argon laser. The authors developed a diode laser-pumped, solid-state, and portable frequency-doubled Nd:YAG laser with a wavelength of 532 nm. The effects of peripheral iridotomy with the frequency-doubled Nd:YAG laser and the argon laser were evaluated in pig eyes in vitro and in rabbit eyes in vivo. Specimens were prepared for light microscopy and scanning electron microscopy. The frequency-doubled Nd:YAG laser successfully created patent iridotomies in all animal eyes treated. The following parameters were used to create penetrating burns: duration of 0.1 second, spot size of 100 microns, and power of 500 mW. In rabbit eyes, the mean number of pulses (P = .16) and the total energy required (P = .21) for iridotomy were not significantly different for the argon laser compared with the frequency-doubled Nd:YAG laser. Gross and histologic evaluation showed similar thermal effects in iris tissues for both the frequency-doubled Nd:YAG laser and the argon laser. The mean zone of thermal damage was 178 +/- 19 microns for the frequency-doubled Nd:YAG laser and 163 +/- 24 microns for the argon laser (P = .14). Scanning electron microscopy showed less disruption of the surface of the lesion for the frequency-doubled Nd:YAG laser compared with the argon laser. Successful peripheral iridotomy can be performed with the frequency-doubled Nd:YAG laser. Coagulative effects with the frequency-doubled Nd:YAG were similar to those with the argon laser, and the thermal damage zones were comparable in size.

The Mα and Mβ emission spectra and the MIV and MV absorption spectra have been studied for the rare earth elements. It is conclusively shown that the complicated multiplet structure observed in the emission spectra is not real emission structure but is, instead, produced by sample self-absorption. This is demonstrated by observing the emission spectra over wide variations in take-off angle and bombarding-electron energies and finally by comparing the detailed structure of both the emission and absorption spectra. The MIV and MV absorption structure completely overlaps the Mα and Mβ emission lines which are each found to have but one intensity maximum when obtained under conditions of minimum self-absorption. Some of these spectra have never been shown previously, while others have been studied in detail by several investigators. Points of agreement and disagreement with previous work are mentioned and the wavelengths of the emission lines and absorption edges are listed for all of the lanthanides. It is concluded that 4f→3d electron transitions are reversible in these elements.

Synthesis, characterization and luminescence properties of europium(III) and terbium(III) complexes with 2-pyrazinecarboxylic acidCrystal structure of [Eu(pyca)3(H2O)2]a6H2O

Abstract. Glyoxal and methylglyoxal are key products of oxidative photochemistry in the lower troposphere. Reliable measurements of such compounds are critical for testing our understanding of volatile organic compound (VOC) processing in this region. We present a new method for obtaining sensitive, high time resolution, in situ measurements of these compounds via laser-induced phosphorescent decays. By exploiting the unique phosphorescent lifetimes for each molecule, this method achieves speciation and high-sensitivity quantification of both molecules. With two different light sources at different wavelengths, the lowest 3σ limits of detection observed during calibration with this method are 11 pptv in 5 min for glyoxal and 243 pptv in 5 min for methylglyoxal. During ambient measurements of glyoxal, a 3σ limit of detection of <4.4 pptv in 5 min was observed. Additionally, this method enables the simultaneous measurement of both glyoxal and methylglyoxal using a single, non-wavelength-tunable light source, which will allow for the development of inexpensive (~$40 k) and turnkey instrumentation. The simplicity and affordability of this new instrumentation would enable the construction of a long-term, spatially distributed database of these two key species. This chemical map can be used to constrain or drive regional or global models as well as provide verification of satellite observations.