scholarly journals Arel – Investigating [Eu(H2O)9]3+ photophysics and creating a method to by-pass luminescence quantum yield determinations

2022 ◽  
Author(s):  
Nicolaj Kofod ◽  
Patrick Nawrocki ◽  
Thomas Just Sørensen
Keyword(s):  
Transition Probabilities ◽  
Lanthanide Ions ◽  
Oscillator Strengths ◽  
Quantum Yields ◽  
Lanthanide Luminescence ◽  
Full Control ◽  
Sample Composition ◽  
Trivalent Lanthanide ◽  
Intensity Changes ◽  
Control Knowledge

Lanthanide luminescence has been treated separate from molecular photophysics, although the underlying phenomena are the same. As the optical transitions observed in the trivalent lanthanide ions are forbidden, they do belong to the group that molecular photophysics have yet to conquer, yet the experimental descriptors remains valid. Determining these have proven challenging as full control/knowledge of sample composition is a prerequisite. This has been achieved, and here the luminescence quantum yields (ϕlum), luminescence lifetimes (τobs), oscillator strengths (f ), and the rates of non-radiative (knr) and radiative (kr ≡ A) deactivation of [Eu(H2O)9]3+ was determined for the trigonal tricapped prismatic (TTP) coordination geometry. Further, it was shown that instead of a full photophysical characterization, it is possible to relate changes in transition probabilities to the relative parameter Arel, which does not require reference data. While Arel does not afford comparisons between experiments, it resolves emission intensity changes due to emitter properties—changes in A—from intensity changes due to environmental effects—changes in knr, and differences in the number of photons absorbed. When working with fluorescence this may seem trivial, when working with lanthanide luminescence it is not.

scholarly journals The Temperature Dependence of Fundamental Photophysical Properties of [Eu(MeOH-d4)9]3+ Solvates and [Eu.DOTA(MeOH-d4)]- Complexes

2021 ◽  
Author(s):  
Nicolaj Kofod ◽  
Lea Gundorff Nielsen ◽  
Thomas Just Sørensen
Keyword(s):  
Transition Probabilities ◽  
Photophysical Properties ◽  
Transition Probability ◽  
Energy Levels ◽  
Emission Spectra ◽  
Lanthanide Ions ◽  
Quantum Yields ◽  
Luminescence Spectra ◽  
Absorption Cross ◽  
Apparent Lack

The trivalent lanthanide ions show optical transitions between energy levels within the 4f shell. All these transitions are formally forbidden according to the quantum mechanical selection rules used in molecular photophysics. Nevertheless, highly luminescent complexes can be achieved, and terbium(iii) and europium(iii) ions are particularly efficient emitters. This report started when an apparent lack of data in the literature led us to revisit the fundamental photophysics of europium(iii). The photophysical properties of two complexes – [Eu.DOTA(MeOH-d4)]- and [Eu(MeOH-d4)9]3+ – were investigated in deuterated methanol at five different temperatures. Absorption spectra showed decreased absorption cross sections as the temperature was increased. Luminescence spectra and time-resolved emission decay profiles showed a decrease in intensity and lifetime as a temperature was increased. Having corrected the emission spectra for the actual number of absorbed photons and differences in non-radiative pathways, the relative emission probability was revealed. These were found to increase with increasing temperature. The transition probability for luminescence was shown to increase with temperature, while the transition probability for light absorption decreased. The changes in transition probabilities were correlated to a change in the symmetry of the absorber or emitter, with an average increase in symmetry lowering absorption cross section and access to more asymmetric structures increasing the emission rate constant. Determining luminescence quantum yields and the Einstein coefficient for spontaneous emission allowed us to conclude that lowering symmetry increases both. Further, it was found that collisional self-quenching is an issue for lanthanide luminescence, when high concentrations are used. Finally, detailed analysis revealed results that show the so-called ‘Werts’ method’ for calculating radiative lifetimes and intrinsic quantum yields are based on assumption that does not hold for the two systems investigated here. We conclude that we are lacking a good theoretical description of the intraconfigurational f-f transition, and that there are still aspects of fundamental lanthanide photophysics to be explored.<br>

On the interpretation of complex atomic spectra by means of the parametric Racah–Slater method and Cowan codes1This article is part of a Special Issue on the 10th International Colloquium on Atomic Spectra and Oscillator Strengths for Astrophysical and Laboratory Plasmas.

2011 ◽  
Vol 89 (4) ◽  
pp. 451-456 ◽  
Author(s):  
Jean-François Wyart
Keyword(s):  
Transition Probabilities ◽  
Energy Levels ◽  
Lanthanide Ions ◽  
Oscillator Strengths ◽  
Effective Parameters ◽  
International Colloquium ◽  
Atomic Spectra ◽  
Laboratory Plasmas ◽  
New Energy ◽  
Electronic Configurations

Theoretical studies of electronic configurations of several lanthanide ions in the Racah–Slater approach were performed with the standard suite of codes by R.D. Cowan, including a fitting of energy parameters. Configuration interaction was considered explicitly in the low configurations and was processed by effective parameters for doubly-excited far configurations. Mean errors lower than 100 cm–1 were obtained. Systematic differences are noticed between radial integrals calculated by ab initio PHFR and the Pfit fitted values. The consistency of the scaling factors SF(P) = Pfit/PHFR and of the effective parameters for far configuration effects is shown. In an application to Tm II, the predicted transition probabilities compared well with line intensities and led to the finding of new energy levels. In Nd II, the configuration 4f5 is identified.

scholarly journals Об экспериментальном определении параметров интенсивности 4f-4f-переходов по спектрам излучения соединений европия (III)

2022 ◽  
Vol 130 (1) ◽  
pp. 207
Author(s):  
Lucca Blois ◽  
Albano N. Carneiro Neto ◽  
Ricardo L. Longo ◽  
Israel F. Costa ◽  
Tiago B. Paolini ◽  
...  
Keyword(s):  
Unique Feature ◽  
Photon Counting ◽  
Emission Spectra ◽  
Lanthanide Ions ◽  
Quantum Yields ◽  
Correction Factors ◽  
Intensity Parameters ◽  
Trivalent Lanthanide ◽  
Integrated Intensity

Eu3+ complexes and specially β-diketonate compounds are well known and studied in several areas due to their luminescence properties, such as sensors and lightning devices. A unique feature of the Eu3+ ion is the experimental determination of the 4f-4f intensity parameters Ωλ directly from the emission spectrum. The equations for determining Ωλ from the emission spectra are different for the detection of emitted power compared to modern equipment that detects photons per second. It is shown that the differences between Ωλ determined by misusing the equations are sizable for Ω4 (ca. 15.5%) for several Eu3+β-diketonate complexes and leads to differences of ca. 5% in the intrinsic quantum yields Q_Ln^Ln. Due to the unique features of trivalent lanthanide ions, such as the shielding of 4f-electrons, which lead to small covalency and crystal field effects, a linear correlation was observed between Ωλ obtained using the emitted power and photon counting equations. We stress that care should be exercised with the type of detection should be taken and provide the correction factors for the intensity parameters. In addition, we suggest that the integrated intensity (proportional to the areas of the emission band) and the centroid (or barycenter) of the transition for obtaining Ωλ should be determined in the properly Jacobian-transformed spectrum in wavenumbers (or energy). Due to the small widths of the emission bands of typical 4f-4f transitions, the areas and centroids of the bands do not depend on the transformation within the experimental uncertainties. These assessments are relevant because they validate previously determined Ωλ without the proper spectral transformation.

The Temperature Dependence of Fundamental Photophysical Properties of [Eu(MeOH-d4)9]3+ Solvates and [Eu.DOTA(MeOH-d4)]- Complexes

2021 ◽  
Author(s):  
Nicolaj Kofod ◽  
Lea Gundorff Nielsen ◽  
Thomas Just Sørensen
Keyword(s):  
Transition Probabilities ◽  
Photophysical Properties ◽  
Transition Probability ◽  
Energy Levels ◽  
Emission Spectra ◽  
Lanthanide Ions ◽  
Quantum Yields ◽  
Luminescence Spectra ◽  
Absorption Cross ◽  
Apparent Lack

The trivalent lanthanide ions show optical transitions between energy levels within the 4f shell. All these transitions are formally forbidden according to the quantum mechanical selection rules used in molecular photophysics. Nevertheless, highly luminescent complexes can be achieved, and terbium(iii) and europium(iii) ions are particularly efficient emitters. This report started when an apparent lack of data in the literature led us to revisit the fundamental photophysics of europium(iii). The photophysical properties of two complexes – [Eu.DOTA(MeOH-d4)]- and [Eu(MeOH-d4)9]3+ – were investigated in deuterated methanol at five different temperatures. Absorption spectra showed decreased absorption cross sections as the temperature was increased. Luminescence spectra and time-resolved emission decay profiles showed a decrease in intensity and lifetime as a temperature was increased. Having corrected the emission spectra for the actual number of absorbed photons and differences in non-radiative pathways, the relative emission probability was revealed. These were found to increase with increasing temperature. The transition probability for luminescence was shown to increase with temperature, while the transition probability for light absorption decreased. The changes in transition probabilities were correlated to a change in the symmetry of the absorber or emitter, with an average increase in symmetry lowering absorption cross section and access to more asymmetric structures increasing the emission rate constant. Determining luminescence quantum yields and the Einstein coefficient for spontaneous emission allowed us to conclude that lowering symmetry increases both. Further, it was found that collisional self-quenching is an issue for lanthanide luminescence, when high concentrations are used. Finally, detailed analysis revealed results that show the so-called ‘Werts’ method’ for calculating radiative lifetimes and intrinsic quantum yields are based on assumption that does not hold for the two systems investigated here. We conclude that we are lacking a good theoretical description of the intraconfigurational f-f transition, and that there are still aspects of fundamental lanthanide photophysics to be explored.<br>

scholarly journals The Temperature Dependence of Fundamental Photophysical Properties of [Eu(MeOH-d4)9]3+ Solvates and [Eu.DOTA(MeOH-d4)]- Complexes

2021 ◽  
Author(s):  
Nicolaj Kofod ◽  
Lea Gundorff Nielsen ◽  
Thomas Just Sørensen
Keyword(s):  
Transition Probabilities ◽  
Photophysical Properties ◽  
Transition Probability ◽  
Energy Levels ◽  
Emission Spectra ◽  
Lanthanide Ions ◽  
Quantum Yields ◽  
Luminescence Spectra ◽  
Absorption Cross ◽  
Apparent Lack

The trivalent lanthanide ions show optical transitions between energy levels within the 4f shell. All these transitions are formally forbidden according to the quantum mechanical selection rules used in molecular photophysics. Nevertheless, highly luminescent complexes can be achieved, and terbium(iii) and europium(iii) ions are particularly efficient emitters. This report started when an apparent lack of data in the literature led us to revisit the fundamental photophysics of europium(iii). The photophysical properties of two complexes – [Eu.DOTA(MeOH-d4)]- and [Eu(MeOH-d4)9]3+ – were investigated in deuterated methanol at five different temperatures. Absorption spectra showed decreased absorption cross sections as the temperature was increased. Luminescence spectra and time-resolved emission decay profiles showed a decrease in intensity and lifetime as a temperature was increased. Having corrected the emission spectra for the actual number of absorbed photons and differences in non-radiative pathways, the relative emission probability was revealed. These were found to increase with increasing temperature. The transition probability for luminescence was shown to increase with temperature, while the transition probability for light absorption decreased. The changes in transition probabilities were correlated to a change in the symmetry of the absorber or emitter, with an average increase in symmetry lowering absorption cross section and access to more asymmetric structures increasing the emission rate constant. Determining luminescence quantum yields and the Einstein coefficient for spontaneous emission allowed us to conclude that lowering symmetry increases both. Further, it was found that collisional self-quenching is an issue for lanthanide luminescence, when high concentrations are used. Finally, detailed analysis revealed results that show the so-called ‘Werts’ method’ for calculating radiative lifetimes and intrinsic quantum yields are based on assumption that does not hold for the two systems investigated here. We conclude that we are lacking a good theoretical description of the intraconfigurational f-f transition, and that there are still aspects of fundamental lanthanide photophysics to be explored.<br>

Bond-length distributions for ions bonded to oxygen: Results for the lanthanides and actinides and discussion of the f-block contraction

2017 ◽  
Author(s):  
Olivier Charles Gagné
Keyword(s):  
Bond Length ◽  
Coordination Number ◽  
Lanthanide Ions ◽  
Lanthanide Contraction ◽  
Trivalent Lanthanide ◽  
Actinide Ions

Bond-length distributions have been examined for eighty-four configurations of the lanthanide ions and twenty-two configurations of the actinide ions bonded to oxygen. The lanthanide contraction for the trivalent lanthanide ions bonded to O<sup>2-</sup> is shown to vary as a function of coordination number and to diminish in scale with increasing coordination number.

A fluorescence study on the complexation of Sm(iii), Eu(iii) and Tb(iii) with tetraalkyldiglycolamides (TRDGA) in aqueous solution, in solid state, and in solvent extraction

2016 ◽  
Vol 45 (46) ◽  
pp. 18484-18493 ◽  
Author(s):  
Fei Kou ◽  
Suliang Yang ◽  
Hongjuan Qian ◽  
Lihua Zhang ◽  
Christine M. Beavers ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Solid State ◽  
Solvent Extraction ◽  
Lanthanide Ions ◽  
Tridentate Ligand ◽  
Fluorescence Study ◽  
Trivalent Lanthanide

Trivalent lanthanide ions form 1 : 1, 1 : 2, and 1 : 3 complexes with tridentate ligand TMDGA in 1 M H/NaNO3 and form 1 : 3 extracted complexes with DMDODGA during solvent extraction.

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