Luminescence spectroscopic investigations of europium complexes formed in the kaolinite-humic acid/citric acid systems

2020 ◽  
Vol 108 (11) ◽  
pp. 859-871
Author(s):  
Parveen Kumar Verma ◽  
Prasanta Kumar Mohapatra
Keyword(s):  
Citric Acid ◽  
Humic Acid ◽  
Emission Spectra ◽  
Luminescence Spectroscopy ◽  
Excitation Spectra ◽  
Europium Complexes ◽  
Ternary Complex Formation ◽  
Kaolinite Surface ◽  
Aqueous Complexation ◽  
The Eu

AbstractIn the present study, the nature of Eu(III) complexes (Eu(III) was used as a surrogate for Am(III)) formed in kaolinite–humic acid (HA)/citric acid (CA) system was investigated by luminescence spectroscopy. In addition to the ternary system (kaolinite + Eu + L(CA/HA)), the binary system (Eu-L) was also looked at for a better understanding of the complexes formed at the kaolinite surface. The lifetime and emission spectra of Eu-L complexes on the kaolinite surface differ considerably as compared to the same in the aqueous phase. The Eu-HA aqueous complexation shows differences in the excitation spectra with similar decay lifetimes with increasing aqueous HA concentrations. The ligand-to-metal charger transfer (LMCT) in the Eu-HA excitation spectra suggests the complexation of Eu(III) with HA at pH ∼ 4. Although the mode of Eu(III) binding to the kaolinite surface in the presence of CA/HA was the same i.e. metal-bridged ternary complex formation, the local surroundings around the sorbed Eu(III) differ in the two cases. The loading of HA in the Eu-HA-kaolinite system does not have a large effect on the local structure around the sorbed Eu(III) ion, but enhances the percentage of Eu(III) uptake onto the kaolinite surface. The number of H2O molecules in the primary hydration sphere of sorbed Eu(III) differs in the Eu-HA-kaolinite and Eu-CA-kaolinite systems. In addition, Eu(III) assisted precipitation of HA was also seen using a radiometric method.

Luminescence spectroscopy of Mn2+ rock-forming carbonates

1989 ◽  
Vol 53 (370) ◽  
pp. 201-211 ◽  
Author(s):  
G. Walker ◽  
O. E. Abumere ◽  
B. Kamaluddin
Keyword(s):  
Simple Model ◽  
Metal Cation ◽  
Room Temperature ◽  
Emission Spectra ◽  
Luminescence Spectroscopy ◽  
Ligand Field ◽  
Absorption Profile ◽  
Excitation Spectra ◽  
Cation Site ◽  
Ligand Field Parameters

AbstractCathodoluminescence emission spectra and luminescence excitation spectra of Mn2+ in calcites, dolomites, magnesites, a manganocalcite and a rhodochrosite have been measured at both room temperature and 77 K. Ligand-field parameters have been calculated from the excitation spectra which reflect the size of the metal cation site in which the Mn2+ ion resides. The technique of luminescence excitation spectra has enabled the absorption profile of Mn2+ in Mg and Ca sites in dolomite to be separately determined. The variation of the distribution of Mn2+ between Mg and Ca sites in dolomites is demonstrated and discussed in terms of a simple model. It is concluded that the distribution of Mn2+ in dolomites may well provide information about its conditions of formation and/or subsequent alteration.

Synthesis, Characterization and Novel Photoluminescence of SrWO4:Ln3+ Nanocrystals

2016 ◽  
Vol 16 (4) ◽  
pp. 3522-3526 ◽  
Author(s):  
Bingyu Xu ◽  
Mingxia Li ◽  
Kai Pan ◽  
Rong Li ◽  
Naiying Fan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Emission Spectra ◽  
Broad Emission Band ◽  
X Ray Diffraction ◽  
Excitation Spectra ◽  
Quenching Effect ◽  
Intense Peak ◽  
Transmission Electron ◽  
A Site ◽  
The Eu

SrWO4:Ln3+ (Ln = Eu, Ce, and Tb) nanocrystals were successfully synthesized by a hydrothermal method, and were characterized by X-ray diffraction, transmission electron microscopy, and scanning electron microscopy. The results indicated that the crystalline size of nanocrystals decreases with increasing Eu3+ concentrations and increases with increasing annealing temperature, gradually. The photoluminescence properties of SrWO4:Ln3+ were investigated in detail. In the emission spectra of SrWO4:Eu3+, the luminescence was dominated by 5D0 → 7F2 transition, indicating that Eu3+ occupied a site lacking inversion symmetry. The concentration quenching effect hardly occurs. In the excitation spectra of SrWO4:Eu3+ nanocrystals monitored at 619 nm, the most intense peak is centered at 467 nm when the Eu3+ concentration was less than 10%, while the most intense peak is centered at 396 nm when the Eu3+ concentration was 15%. In the normalized emission spectra of SrWO4:Ce3+/Tb3+ nanocrystals excited at 254 nm, the intensity ratio of the sharp emission peaks from Tb3+ ions to the broad emission band from Ce3+ ions increased with increasing Tb3+ concentration.

scholarly journals Total luminescence spectroscopy for differentiating between brandies and wine distillates

2009 ◽  
Vol 27 (No. 6) ◽  
pp. 425-432 ◽  
Author(s):  
J. Tóthová ◽  
J. Sádecká ◽  
P. Májek
Keyword(s):  
Multivariate Analysis ◽  
Emission Spectra ◽  
Principal Component ◽  
Hierarchical Cluster ◽  
Luminescence Spectroscopy ◽  
Luminescence Spectra ◽  
Classification Error ◽  
Excitation Wavelength ◽  
Data Sets ◽  
Excitation Spectra

In this study, the differentiation was investigated between brandy and wine distillate samples by fluorescence spectroscopy in combination with multivariate analysis. The samples corresponding to eight brandies from three producers and sixteen wine distillates from five producers were acquired in the local supermarkets. Total luminescence spectra of diluted and undiluted samples were recorded. In order to extract reliable information from the data sets, two multivariate analysis methods, Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA), were applied separately on the excitation and emission spectra. The best differentiation was achieved using the emission spectra (400–470 nm) recorded at the excitation wavelength of 340 nm, or the excitation spectra (240–380 nm) recorded at the emission wavelength of 450 nm. The similarity map defined by the PC1 and PC2 of the PCA performed on the excitation spectra accounted for 94.9% of the total variance (PC1 90.3%, PC2 4.6%) and allowed a good discrimination between the beverages. Although the PCA similarity map defined by the PC1 (84.2%) and PC2 (13.0%) performed on the emission spectra did not lead to a clear discrimination between the beverages, a general trend pointing out the brandies and wine distillates was observed on the map. HCA performed on the excitation spectra provided a better differentiation between the two classes, without any classification error, while HCA performed on the emission spectra allowed 95.8% correct classification.

Eu+3 and Cr+3 doping for red cathodoluminescence in ZnGa2O4

2001 ◽  
Vol 16 (5) ◽  
pp. 1429-1433 ◽  
Author(s):  
Philip D. Rack ◽  
Jeffrey J. Peterson ◽  
Michael D. Potter ◽  
Wounjhang Park
Keyword(s):  
Energy Transfer ◽  
Current Density ◽  
Emission Spectra ◽  
Excitation Spectra ◽  
Efficient Energy Transfer ◽  
Current Saturation ◽  
Red Color ◽  
Red Luminescence ◽  
Intrinsic Emission ◽  
The Eu

Cathodoluminescence emission spectra and photoluminescence (PL) excitation spectra were used to evaluate Eu+3 and Cr+3 as activators for red luminescence in ZnGa2O4. In the ZnGa2O4:Eu materials red emission from Eu+3 and blue intrinsic emission were observed. The blue intrinsic emission increased relative the Eu+3 emission with increasing current density and is attributed to preferential current saturation of the Eu+3 activators. In addition, PL excitation measurements revealed that the inefficient energy transfer from the ZnGa2O4 host to the Eu+3 is due to poor spectral overlap between the ZnGa2O4 emission and the Eu+3 absorption. Cr-doping resulted in a saturated red-color, and no host emission was observed over the entire current density regime investigated. The PL excitation of the ZnGa2O4:Cr revealed good overlap between the ZnGa2O4 host and the Cr+3 absorption. Efficient energy transfer to the Cr+3 activators occurs via multipolar interactions.

Photoluminescence and Photocatalytic Activity of Bi2MoO6:Ln3+ Nanocrystals

2016 ◽  
Vol 16 (4) ◽  
pp. 3781-3785 ◽  
Author(s):  
Li Feng ◽  
Mingxia Li ◽  
Kai Pan ◽  
Rong Li ◽  
Naiying Fan ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Photocatalytic Activity ◽  
Relative Intensity ◽  
Rhodamine B ◽  
Photocatalytic Performance ◽  
Emission Spectra ◽  
Photoluminescence Properties ◽  
Excitation Spectra ◽  
Simulated Solar Light ◽  
The Eu

Sheet-like Bi2MoO6:Ln3+ nanocrystals were synthesized by a hydrothermal method. The crystalline size of Bi2MoO6:Ln3+ (Ln = Eu and Gd) nanocrystals changes gradually with the increasing of Ln3+ content in the reaction solutions. The photoluminescence properties of Bi2MoO6:Ln3+ nanocrystals were investigated in detail. In the emission spectra of Bi2MoO6:Eu3+ nanocrystals the 5D0 →7F2 is much stronger than the 5D0 →7F1 and is the strongest when the excitation is performed at 467 nm. The relative intensity of the transitions from Eu3+ increased with increasing Eu3+ concentrations, up to about 50 mol%, and then decreased abruptly. In the excitation spectra of Bi2MoO6:Eu3+ (30%)/Gd3+ monitored at 618 nm, the 7F0 → 5D2 (∼467 nm) transition is dominating when the Gd3+ concentrations were 10% or 20%. When the Gd3+ concentration was 30%, the 7F0 → 5D1 (∼538 nm) transition is dominating. In addition, the photocatalytic activity of Bi2MoO6:Eu3+ was evaluated by the degradation of rhodamine B (RhB) aqueous solution under simulated solar light. The best photocatalytic performance was observed when the Eu3+ concentration was 1%.

scholarly journals Excitation versus Emission Spectra as a Means to Examine Selective Fluorescence Quenching Agents

1992 ◽  
Vol 46 (9) ◽  
pp. 1388-1392 ◽  
Author(s):  
Sheryl A. Tucker ◽  
William E. Acree
Keyword(s):  
Fluorescence Quenching ◽  
Spectral Data ◽  
Emission Spectra ◽  
Data File ◽  
Excitation Spectra

To ascertain whether fluorescence quenching is best studied with the use of excitation or emission spectra, and to expand our existing PAH spectral data file, we have recorded excitation spectra of benzo[b]perylene, dibenzo[hi,wx]heptacene, tetrabenzo[de,hi,mn,qr]naphthacene, perylene, benzo[a]fluoranthene, benzo[def]indeno[1,2,3hi]chrysene, naphtho[2,1a]fluoranthene, naphtho[2,3b]fluoranthene, benzo[k]fluoranthene, 2-azapyrene, naphtho[8,1,2hij]pyreno[9,10,1def]phthalazine, indeno[1,-2,3ij]isoquinoline, benzo(lmn][3,8]phenanthroline, and 7-methyldibenzo(b,def]chrysene at various nitromethane concentrations. Results of these measurements verify our earlier observations concerning the nitromethane selective quenching rule and further illustrate the importance of considering inner-filtering artifacts in quenching studies.

Synthesis and Characterization of Y2O3:Eu3+ Film Derived by Sol-Gel Processing

2007 ◽  
Vol 336-338 ◽  
pp. 593-596
Author(s):  
Chun Yang ◽  
Jun Ying Zhang ◽  
Hai Bing Feng ◽  
Wei Chang Hao ◽  
Tian Min Wang
Keyword(s):  
Raw Materials ◽  
Sol Gel ◽  
Emission Spectra ◽  
Luminescent Properties ◽  
Dip Coating ◽  
Organic Additive ◽  
Excitation Spectra ◽  
Excitation Peak ◽  
Close Relationship ◽  
Dip Coating Technique

Y2O3:Eu3+ thin film was synthesized by sol-gel method with inorganic salt raw materials, and the crystal structure and luminescent properties were investigated. By adding organic additive to the sol, a homogeneous film with high luminescent intensity could be obtained by dip-coating technique on the surface of alumina sheet and quartz glass. Structures of the films were studied by XRD and SEM. The excitation spectra of the films showed a wide excitation peak from 200nm to 260nm, and the emission spectra had a strongest emission peak at 611nm which revealed a close relationship with the calcining temperature.

scholarly journals Heterogeneous Uptake of Amines by Citric Acid and Humic Acid

2012 ◽  
Vol 46 (20) ◽  
pp. 11112-11118 ◽  
Author(s):  
Yongchun Liu ◽  
Qingxin Ma ◽  
Hong He
Keyword(s):  
Citric Acid ◽  
Humic Acid

Study of Temperature Behavior of Luminescence Emission of LaVO4 and La1-xEuxVO4 Powders

2015 ◽  
Vol 230 ◽  
pp. 153-159 ◽  
Author(s):  
Oksana Chukova ◽  
Sergiy G. Nedilko ◽  
Sergiy A. Nedilko ◽  
Tetiana Voitenko ◽  
Olga Gomenyuk ◽  
...  
Keyword(s):  
Emission Spectra ◽  
Spectral Lines ◽  
Temperature Behavior ◽  
Precipitation Method ◽  
Temperature Range ◽  
Luminescence Emission ◽  
Electron Transitions ◽  
The Matrix ◽  
Co Precipitation ◽  
The Eu

The La1‑xEuxVO4 powders were synthesized by co-precipitation method. Emission spectra of the LaEuVO4 and La1‑xEuxVO4 powders consist of wide non-structural bands of the matrix emission and narrow spectral lines caused by inner f-f electron transitions in the Eu3+ ions, respectively. The both types of emission were studied within 8 – 300 K temperature range. Decomposition of spectra of the wide matrix emission on three bands has been carried out and temperature dependencies for each band were studied. Temperature behavior of the Eu3+ emission was investigated for lines assigned to different Eu3+ centres. Obtained dependencies are analyzed and discussed using proposed schemes of transitions in the VO43- groups and structure of the nearest surrounding of the Eu3+ emission centres.

scholarly journals Spectrofluorimetric Determination of Hydrochlorothiazide by a Carbon Dots-Based Probe via Inner Filtering Effect and Resonance Rayleigh Scattering

2022 ◽  
Author(s):  
Ali Ghafarloo ◽  
Reza Sabzi ◽  
Naser Samadi ◽  
Hamed Hamishehkar
Keyword(s):  
Carbon Dots ◽  
Rayleigh Scattering ◽  
Limit Of Detection ◽  
Fluorescent Sensor ◽  
Emission Spectra ◽  
Cost Effective ◽  
Inner Filter Effect ◽  
Resonance Rayleigh Scattering ◽  
Excitation Spectra ◽  
One Pot

Synthesis of carbon dots (CDs) from natural resources not only enables green synthesis and production of environmentally friendly materials, but also provides a cost-effective probe as a fluorescence nanosensor. The proposed sensor introduces a unique one-pot hydrothermal CDs synthesis from alfalfa leaves, which is promising for sensing hydrochlorothiazide (HCTZ) via inner filter effect (IFE) and resonance Rayleigh scattering (RRS). The as-prepared CDs had wide emission spectra, excitation-dependent emission, high solubility, high stability, and visible fluorescence light with a quantum yield of up to 11%. The absorption of HCTZ overlapped with the excitation spectra of CDs. Therefore, CDs represented excellent quenching due to IFE when HCTZ was gradually added. Furthermore, this fluorescent sensor was successfully used to quantify HCTZ in the linear ranges (0.17-2.50 μg mL-1) with the limit of detection of 0.11 μg mL-1. The sensing system was simple as no surface functionalization was required for CDs, leading to less laborious steps and more cost-effective synthesis. The reaction time was short, i.e., less than 2 min, indicating a simple approach for rapid analysis of HCTZ. By optimizing conditions, successful measurements were carried out on pharmaceutical tablets.

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