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>

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>

scholarly journals Large Scale Shell Model Calculations of the Negative-Parity States Structure in 24Mg Nucleus

2021 ◽  
Vol 66 (4) ◽  
pp. 293
Author(s):  
A.A. Al-Sammarraie ◽  
F.A. Ahmed ◽  
A.A. Okhunov
Keyword(s):  
Shell Model ◽  
Large Scale ◽  
Transition Probabilities ◽  
Transition Probability ◽  
Energy Levels ◽  
Form Factors ◽  
Model Space ◽  
Negative Parity ◽  
Matrix Elements ◽  
Model Calculations

The negative-parity states of 24Mg nucleus are investigated within the shell model. We are based on the calculations of energy levels, total squared form factors, and transition probability using the p-sd-pf (PSDPF) Hamiltonian in a large model space (0 + 1) hW. The comparison between the experimental and theoretical states showed a good agreement within a truncated model space. The PSDPF-based calculations successfully reproduced the data on the total squared form factors and transition probabilities of the negative-parity states in 24Mg nucleus. These quantities depend on the one-body density matrix elements that are obtained from the PSDPF Hamiltonian. The wave functions of radial one-particle matrix elements calculated with the harmonic-oscillator potential are suitable to predict experimental data by changing the center-of-mass corrections.

Enhanced Luminescence of Terbium Complexes with 2,3-Pyrazinedicarboxylate by Y(III) Doping

2013 ◽  
Vol 750-752 ◽  
pp. 1007-1010
Author(s):  
Ai Ling Wang ◽  
Hai Xia Zhang ◽  
Kai Kong ◽  
Huan Huan Li ◽  
Hua Wang ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Lanthanide Complexes ◽  
The Self ◽  
Lanthanide Ions ◽  
Quantum Yields ◽  
Luminescence Spectra ◽  
Intramolecular Energy Transfer ◽  
Enhanced Luminescence ◽  
Yttrium Complexes ◽  
Terbium Complexes

Ten kinds of terbium doped inert yttrium complexes with 2,3-pyrazinedicarboxylate (2,3-pzdc2-) have been synthesized. Characterization results indicate that the complexes have the compositions of Tb (pzdc)1.55H2O and TbxYy(pzdc)1.55H2O (x:y=0.10:0.90; 0.20:0.80; 0.30:0.70; 0.40:0.60; 0.60:0.40; 0.70:0.30; 0.80:0.20; 0.90:0.10). IR spectra show that the lanthanide ions coordinate with the carboxylic oxygen atoms and nitrogen atoms of the ligands. Luminescence spectra show that the Y(III) ions can remarkably increase the luminescent intensities of terbium complexes. And Tb0.7Y0.3(pzdc)1.55H2O exhibits the strongest luminescent emission. Furthermore, the doped lanthanide complexes show longer luminescence lifetimes and higher quantum yields. The enhanced luminescence efficiencies of Tb3+ions in the doped complexes may result from intramolecular energy transfer as well as the decrease of the self-quench of the Tb3+ions induced by the doped Y(III) ions.

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.

Luminescence Properties of Inert Lanthanide Ion Doped Europium Complexes with 2-Pyrazinecarboxylic Acid and Butanedioic Acid

2012 ◽  
Vol 271-272 ◽  
pp. 55-59
Author(s):  
Ming Yan Zhao ◽  
Rui Jun Ma ◽  
Ying Nan Chen ◽  
Hai Xia Zhang ◽  
Kai Kong ◽  
...  
Keyword(s):  
Low Cost ◽  
Peak Position ◽  
Lanthanide Ions ◽  
Quantum Yields ◽  
Luminescence Spectra ◽  
Europium Complexes ◽  
Strong Luminescence ◽  
Pyrazinecarboxylic Acid ◽  
Butanedioic Acid ◽  
Oxygen Atoms

Nine europium complexes with 2-pyrazinecarboxylic acid (Hpyca) and butanedioic acid (HBDA) were synthesized and characterized by elemental, IR, EDTA titration, ICP, and TG-DSC analyses. The results show that the complexes have the compositions of Eu(Pyca)(BDA)•2H2O, Eu0.7La0.3(Pyca)(BDA)•2H2O, Eu0.6La0.4(pyca)(BDA)•3H2O, Eu0.5La0.5(pyca)(BDA)•4H2O, Eu0.7Y0.3(Pyca)(BDA)•3H2O, Eu0.6Y0.4 (Pyca)(BDA)•2H2O, Eu0.5Y0.5(Pyca)(BDA)•3H2O, Eu0.7Gd0.3(Pyca)(BDA)•2H2O and Eu0.5Gd0.5(Pyca)(BDA)•2H2O. IR spectra indicate that lanthanide ions coordinate with the carboxylic oxygen atoms and nitrogen atoms of Hpyca and oxygen atoms of HBDA. Luminescence spectra show that the introduction of La3+, Y3+ or Gd3+ in the complexes does not change the luminescence peak position, but remarkably increases luminescent intensity of the europium complexes. The quantum yields of the complexes doped with inert lanthanide ions (La3+, Y3+ or Gd3+) are higher than that of the undoped europium complex. Furthermore, doping the inert lanthanide ions in right proportion can increase the luminescence lifetimes of complexes. Those complexes are of strong luminescence, low cost and practical value.

Synthesis and Photoluminescence Properties of Doped Europium Complexes with 2-Pyrazinecarboxylate

2011 ◽  
Vol 399-401 ◽  
pp. 963-966
Author(s):  
Hai Xia Zhang ◽  
Rui Jun Ma ◽  
Hai Bin Chu ◽  
Ming Yan Zhao ◽  
Ying Nan Chen ◽  
...  
Keyword(s):  
Low Cost ◽  
Lanthanide Ions ◽  
Quantum Yields ◽  
Luminescence Spectra ◽  
Intramolecular Energy Transfer ◽  
Dsc Analysis ◽  
Practical Application ◽  
Photoluminescence Properties ◽  
Europium Complexes ◽  
Strong Luminescence

Seven europium complexes of 2-pyrazinecarboxylate (pyca) doped with inert fluorescent lanthanide ions (La3+, Y3+) have been synthesized. Elemental analysis, IR spectroscopy, absorption spectroscopy and TG-DSC analysis showed that the complexes have the formulas of Eu(pyca)3•3H2O and EuxRE1-x(pyca)3•3H2O (RE=La, Y; x = 0.7,0.5,0.3), respectively. The lanthanide ions coordinated with carboxylic oxygen atoms and nitrogen atoms of pyca. Luminescence spectra and luminescence life-times of the complexes have been measured and their quantum yields were calculated. The results showed that the existence of La3+and Y3+ions could enhance the luminescence intensity and quantum yield of the europium complexes, which may arise from the intramolecular energy transfer between the inert fluorescent lanthanide ions and Eu3+ion. Those doped complexes have the advantages of strong luminescence, low cost and practical application value.

Kα transition probabilities of C-like to F-like Al ions

2015 ◽  
Vol 93 (3) ◽  
pp. 267-270
Author(s):  
Cuicui Sang ◽  
Feng Chen ◽  
Chao Chen ◽  
Bingcong Gou
Keyword(s):  
Transition Probabilities ◽  
Energy Levels ◽  
Emission Spectra ◽  
Radiative Transition ◽  
Transition Rates ◽  
Atomic Structures ◽  
Radiative Transitions ◽  
Electron Correlation Effects ◽  
Reasonable Description ◽  
Spectral Intensities

Kα radiative transitions of C-like to F-like Al ions are studied using the multiconfiguration Dirac–Fock (MCDF) method. The fully relativistic MCDF approach was specifically designed to calculate atomic structures and radiative transition rates, and hence it ensures a reasonable description of the emission effects and spectral intensities. The energies and wavefunctions, corresponding mixing coefficients, the influence of electron correlation effects on energy levels, and radiative transition rates for C-like to F-like Al ions are investigated in detail. Good agreement is found between the calculated Kα emission spectra in this work and the spectra from experimental measurements.

scholarly journals Synthesis and Photophysical Properties of a Series of Dimeric Indium Quinolinates

Molecules ◽  
2020 ◽  
Vol 26 (1) ◽  
pp. 34
Author(s):  
Sang Woo Kwak ◽  
Ju Hyun Hong ◽  
Sang Hoon Lee ◽  
Min Kim ◽  
Yongseog Chung ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Nmr Spectroscopy ◽  
1H Nmr Spectroscopy ◽  
Photophysical Properties ◽  
Emission Spectra ◽  
Solvent Polarity ◽  
Low Energy ◽  
Quantum Yields ◽  
Absorption Bands ◽  
Indium Complexes

A novel class of quinolinol-based dimeric indium complexes (1–6) was synthesized and characterized using 1H and 13C(1H) NMR spectroscopy and elemental analysis. Compounds 1–6 exhibited typical low-energy absorption bands assignable to quinolinol-centered π–π* charge transfer (CT) transition. The emission spectra of 1–6 exhibited slight bathochromic shifts with increasing solvent polarity (p-xylene < tetrahydrofuran (THF) < dichloromethane (DCM)). The emission bands also showed a gradual redshift, with an increase in the electron-donating effect of substituents at the C5 position of the quinoline groups. The absolute emission quantum yields (ΦPL) of compounds 1 (11.2% in THF and 17.2% in film) and 4 (17.8% in THF and 36.2% in film) with methyl substituents at the C5 position of the quinoline moieties were higher than those of the indium complexes with other substituents.

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.

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