Influence ofpH and concentration of complexing agents on fluorescence of samarium(III), gadolinium(III), and terbium(III)—Ethylenediaminetetraacetic acid or nitrilotriacetic acid complexes in aqueous solutions

The fluorescence intensity of aqueous solutions of Sm(III), Gd(III) and Tb(III) complexes withEDTA orNTA was investigated as a function of complexone concentration over a widepH range. For Sm(III) and Tb(III) complexes the ratio of intensities of hypersensitive and allowed bands was calculated in order to obtain information about intensity borrowing of the fluorescence bands as a result of vibronic coupling.     

Energy transfer in solution of lanthanide complexes

The lanthanides with their well-defined energy levels provide an excellent basis to study different Ln(III)-specific energy transfer processes in a variety of chemical environments. The studies concerning intramolecular and intermolecular energy transfer processes with participation of Ln(III) ions and a variety of ligand groups in solution are reviewed. Phenomena of energy transfer from ligands to Ln(III) ions, resulting consequently in a great enhancement of the Ln(III) ion luminescence (ligand sensitized luminescence), as well as from Ln(III) to other species and between Ln(III) ions are presented.     

A STUDY OF THE PHOTOPHYSICAL AND PHOTOCHEMICAL PROPERTIES OF THE S8 MOLECULE Photochemical Reactions in the S8 + Liquid Methanol System with and without Sensitizers: Benzene,Naphthalene and Pyrene. II

Abstract

The photochemical reactions occurring in the system S₈ + CH₃OH in the liquid phase were investigated, in the presence of, and without sensitizers. The experimental conditions were identical with those employed in studying the quenching of fluorescence.¹

The decay of S₈ is more rapid in the presence of sensitizers (the quantum yield and the degree of conversion are higher). In the system studied irradiation by UV light (λ 254 nm) causes the formation of (CH₃)₂S and of trace amounts of CH₄ and C₂H₆. The process of S₈ decay is of a mixed kinetic character—a pseudo 1st order process predominating, with a contribution from a 2nd order reaction. A possible reaction scheme, associated with excitation energy transfer from sensitizers to S₈ is discussed.     

Chemometric and statistical analysis of polyoxometalate interaction with lanthanide(III) ions

Application of CAT (computer-assisted target factor analysis) for quality assessment and quality control in spectroscopy is demonstrated. As a working example, interaction of polyoxometalates (POM) with neodymium in aqueous solutions is followed by UV-Vis spectroscopy. CAT is combined with Monte Carlo and resampling techniques (i.e. threshold bootstrap methods) in order to capture the complete distribution of suitable interpretations of the systems under study. Decisions during the evaluation process are based on statistical criteria conditional on the empirical distributions obtained from CAT. Single component spectra of the Nd-POM solution species are extracted and species concentrations in the experimental samples are obtained together with their respective confidence limits.     

Quantum efficiency of the luminescence of Eu(III), Tb(III) and Dy(III) in aqueous solutions

Summary The luminescence quantum efficiency of Eu(III), Tb(III) and Dy(III) in chloride solutions as well as complexed by aminopolyacetic acids was determined. An interpretation of the observed dependences in the system investigated has been proposed.

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Die Lumineszenz-Quantenausbeute von Eu(III), Tb(III) und Dy(III) in wäßrigen Lösungen

Zusammenfassung Die Lumineszenz-Quantenausbeute von Eu(III), Tb(III) und Dy(III) in Chloridlösung und in Komplexen mit Aminopolyessigsäuren wurde bestimmt. Eine Interpretation der beobachteten Abhängigkeiten im untersuchten System wurde vorgeschlagen.

     

Spectrofluorimetric determination of trace amounts of Tb(III) using acetylacetone in ethanol solution

Summary The spectrofluorimetric determination of terbium(III) in ethanol (95%) solution of acetylacetone (3×10^–4 mol/l) was studied. Intensive fluorescence of terbium(III) (=545 nm) was observed after excitation of the system (=310 nm). The method proposed is satisfactory for the determination of terbium(III) in the range of 4 to 40 ng/ml (2.5×10^–8 to 2.5×10^–7 mol/l). The effect of other rare earths, common metal ions and anions upon the intensity of the fluorescence emitted by terbium(III) is discussed.

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Spektrofluorimetrische Bestimmung von Tb(III)-Spuren mit Acetylaceton in Ethanollösung

     

Quenching of the triplet state of benzophenone by lanthanide 1,3-diketonate chelates in solutions

The phosphorescence of benzophenone in benzene and acetonitrile was quenched by several lanthanide (Sm, Eu, Gd, Tb and Dy) acetylacetonate chelates. The results ofStern-Volmer analysis including the quenching of benzophenone triplet and sensitization of lanthanide emission indicate that the quenching process occurs by the energy transfer mechanism via the excited triplet state of the ligand.

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Löschung des Triplettzustandes von Benzophenon mittels Lanthanid-1,3-Diketonat-Chelatverbindungen in Lösung

Zusammenfassung Die Phosphoreszene von Benzophenon in Benzophenon in Benzen und Acetonitril wurde durch 1,3-Diketonat-Chelatverbindungen von einigen Lanthaniden (Sm, Eu, Gd, Tb und Dy) gelöscht. Die Resultate derStern-Volmer-Analyse einschließlich der Auslöschung des Benzophenon-Tripletts und die Sensibilisierung der Lanthanid-Emission zeigen, daß der Löschprozeß mittels Energieübertragungsmechanismus via angeregtem Triplettzustand des Liganden stattfindet.

     

Chemiluminescence of systems containing lanthanide ions

A review of the chemiluminescent reactions in the systems containing lanthanide ions as emitters and different chemical compounds is presented. The systems in which lanthanide ions enhance the chemiluminescence intensity, thanks to the energy transfer processes, as well as the systems in which redox reactions involving lanthanide ions cause chemiluminescence and the systems showing electrogenerated luminescence and lyoluminescence are discussed.