1,720,994 research outputs found
Quantification of Emission Efficiency in Persistent Luminescent Materials [Dataset]
No full textAccurate quantification of efficiency enables rigorous comparison between different photoluminescent materials, providing an optimization path critical to the development of next-generation light sources. Persistent luminescent materials exhibit delayed and long-lasting luminescence due to the temporary storage of optical energy in engineered structural defects. Although these materials have recently gained attention for their potential in a wide range of applications, from smart lighting to in vivo imaging, standard characterization methods do not provide a universal comparison of phosphor performance, making it difficult to assess the efficiency of the different processes involved in afterglow. In this work we establish a protocol to obtain the emission quantum yield of persistent phosphors. We determine the persistent and total luminescence quantum yields by considering the ratio of photons emitted in the afterglow and during charging to those absorbed. The method is first applied to transparent single crystals of the most common persistent phosphors, such as SrAl2O4:Eu2+,Dy3+ and Y3Al2Ga3O12:Ce3+,Cr3+. The versatility of our methodology is then demonstrated by quantifying the quantum yield of a thin film based on ZnGa2O4:Cr3+ persistent luminescent nanoparticles, which are commonly used for in vivo imaging. We confirm the high efficiency of strontium aluminate and reveal a strong dependence of the obtained values on the illumination conditions, highlighting a trade-off between efficiency and brightness, which opens the door to precise optimization of the charging conditions for each material and application. Our results contribute to the development of standard characterization protocols for the analysis of the mechanisms governing afterglow, as well as the assessment of the overall efficiency of the process. Such achievements enable a rigorous comparison of the performance of different persistent materials, allowing for optimization routes beyond the usual trial-and-error approach.This project has received funding from the BBVA Foundation Leonardo Grant for Physics Researchers 2023, and by Grant EUR2023-143467 funded by MICIU/AEI/ 10.13039/501100011033 and by the European Union NextGenerationEU/PRTR. V.C. acknowledges Junta de Andalucía for financial support (POSTDOC_21_00694).File List: - Fig1b_KineticScansSAOEuDy.txt : Time (s, column 1), normalized intensity kinetic scans of empty sphere at 400 nm used to calculate Abs (column 2), SAO:Eu,Dy at 400 nm used to calculate Abs (column 3) and SAO:Eu,Dy at 524 nm (column 4). - Fig1c_PersLSpectrumSAOEuDy.txt : Wavelength (nm, column 1), normalized PersL intensity of SAO:Eu,Dy (column 2). - Fig1d_LumSpectrumSAOEuDy.txt : Wavelength (nm, column 1), normalized Lum intensity of SAO:Eu,Dy (column 2). - Fig2a_QYSAOEuDyChargingTime.txt : Charging time (s, column 1), LumQY of SAO:Eu,Dy (column 2), error of LumQY of SAO:Eu,Dy (column 3), PersLQY of SAO:Eu,Dy (column 4) and error of PersLQY of SAO:Eu,Dy (column 5). - Fig2b_ChargingKineticSAOEuDy.txt : Wavelength (nm, column 1), normalized Lum intensity of SAO:Eu,Dy (column 2). - Fig3c_SpectraZGOCr.txt : Wavelength (nm, column 1), normalized Lum intensity of ZGO:Cr (column 2), Wavelength (nm, column 3) and normalized PersL intensity of ZGO:Cr (column 4). - Fig3d_KineticScansZGOCr.txt : Time (s, column 1), normalized intensity kinetic scans of empty sphere at 270 nm used to calculate Abs (column 2), ZGO:Cr at 260 nm used to calculate Abs (column 3) and ZGO:Cr at 696 nm (column 4). - Fig3e_PersLESpectrumZGOCr.txt : Wavelength (nm, column 1) and normalized PersLE intensity of ZGO:Cr (column 2). - Fig4a_IntegratedPersLTemperature.txt : Time after excitation (s, column 1), normalized integrated intensity of ZGO:Cr at RT after excitation at 270 nm (column 2), normalized integrated intensity of ZGO:Cr after excitation at 270 nm with heating at 85 ºC (column 3), Time after excitation (s, column 4), normalized integrated intensity of ZGO:Cr at RT after excitation at 330 nm (column 5), normalized integrated intensity of ZGO:Cr after excitation at 330 nm with heating at 85 ºC (column 6), normalized integrated intensity of SAO:Eu,Dy at RT after excitation at 400 nm (column 7), normalized integrated intensity of SAO:Eu,Dy after excitation at 400 nm with heating at 85 ºC (column 8).Peer reviewe
Refractive Index and Strain Modulation Tailor the Afterglow of Nanocomposite Films
No full textTailoring the unique delayed and long-lasting luminescence of persistent phosphors is crucial for their application in anticounterfeiting, data storage, imaging displays, and AC-driven lighting. We introduce a novel strategy to achieve this by modifying the refractive index of persistent phosphor transparent coatings. Specifically, we developed ZnGa2O4:Cr3+/SiO2 nanocomposite films with tunable refractive indices from 1.45 to 1.7. This tunability allowed us to precisely control the Cr3+ radiative decay rate, resulting in a substantial 1.7-fold increase in both luminescence and afterglow brightness. Furthermore, our approach uniquely influences the intrinsic charging rate of the phosphor, a mechanism attributed to the strain induced on the ZnGa2O4:Cr3+ nanocrystals by the presence of SiO2. This work demonstrates an unprecedent ability to manipulate the afterglow kinetics without altering the material composition, opening new avenues for designing and optimizing persistent luminescence materials.We thank Bruno Viana and Juan R. Sánchez-Valencia for their assistance with thermoluminescence and ellipsometry measurements, respectively. This project has received funding from the BBVA Foundation Leonardo Grant for Physics Researchers 2023, and by the Spanish Ministry of Science, Innovation and Universities under Grant EUR2023-143467 funded by MICIU/AEI/10.13039/501100011033 and by the European Union NextGenerationEU/PRTR, and under grant PID2024-161708OB-I00 funded by MICIU/AEI/10.13039/501100011033. Author V.C. acknowledges Junta de Andalucía for financial support (POSTDOC_21_00694). Author M.R. acknowledges Grant FPU23/01435, funded by MCIN/AEI/10.13039/501100011033. Author A.J.F.-C. acknowledges support from the Junta de Andalucía through the EMERGIA program (grant 2022/00001043).Peer reviewe
Supporting Information: Refractive Index and Strain Modulation Tailor the Afterglow of Nanocomposite Films
No full textBallistic transmittance and transparency measurements; XRD patterns; ellipsometry spectra and fittings; transmission and reflection measurements; SEM image of SiO2 NP thick films; PL excitation spectra, PL decay and PLQY measurements; normalized TL glow curves and time-dependent afterglow decays; results of ellipsometry fits, results of UMA fits, and parameters used to fit luminescence kinetic scans using the local modelTailoring the unique delayed and long-lasting luminescence of persistent phosphors is crucial for their application in anticounterfeiting, data storage, imaging displays, and AC-driven lighting. We introduce a novel strategy to achieve this by modifying the refractive index of persistent phosphor transparent coatings. Specifically, we developed ZnGa2O4:Cr3+/SiO2 nanocomposite films with tunable refractive indices from 1.45 to 1.7. This tunability allowed us to precisely control the Cr3+ radiative decay rate, resulting in a substantial 1.7-fold increase in both luminescence and afterglow brightness. Furthermore, our approach uniquely influences the intrinsic charging rate of the phosphor, a mechanism attributed to the strain induced on the ZnGa2O4:Cr3+ nanocrystals by the presence of SiO2. This work demonstrates an unprecedent ability to manipulate the afterglow kinetics without altering the material composition, opening new avenues for designing and optimizing persistent luminescence materials.Peer reviewe
DATASET Refractive index and strain modulation tailor the afterglow of nanocomposite films
No full textTailoring the unique delayed and long-lasting luminescence of persistent phosphors is crucial for their application in anti-counterfeiting, data storage, imaging displays, and AC-driven lighting. We introduce a novel strategy to achieve this by modifying the refractive index of persistent phosphor transparent coatings. Specifically, we developed ZnGa2O4:Cr3+/SiO2 nanocomposite films with tunable refractive indices from 1.45 to 1.7. This tunability allowed us to precisely control the Cr3+ radiative decay rate, resulting in a substantial 1.7-fold increase in both luminescence and afterglow brightness. Furthermore, our approach uniquely influences the intrinsic charging rate of the phosphor, a mechanism attributed to the strain induced on the ZnGa2O4:Cr3+ nanocrystals by the presence of SiO2. This work demonstrates an unprecedent ability to manipulate the afterglow kinetics without altering the material composition, opening new avenues for designing and optimizing persistent luminescence materials.This project has received funding from the BBVA Foundation Leonardo Grant for Physics Researchers 2023, and by the Spanish Ministry of Science, Innovation and Universities under Grant EUR2023-143467 funded by MICIU/AEI/ 10.13039/501100011033 and by the European Union NextGenerationEU/PRTR, and Grant PID2024-161708OB-I00 funded by MICIU/AEI/ 10.13039/501100011033. V.C. acknowledges Junta de Andalucía for financial support (POSTDOC_21_00694). MR acknowledges the grant FPU23/01435 funded by MCIN/AEI/10.13039/501100011033.Peer reviewedFile List:
- Fig1b_ParticleDiameter.txt : Number of particles (column 1), ZnGa2O4:Cr3+ particle diameter (column 2) and SiO2 particle diameter (column 3).
- Fig1i_XRD.txt : 2 theta (º, column 1), normalized XRD reflection intensity of 100:0 1000 °C (column 2), 100:0 800 °C (column 3), 50:50 1000 °C (column 4), 50:50 800 °C (column 5).
- Fig1j_Strain.txt : SiO2 content (%, column 1), Strain 404 of 1000 °C samples (column 2), Strain 404 of 800 °C samples (column 3), cubic lattice parameter relative variation of 1000 °C samples (column 4), cubic lattice parameter relative variation of 800 °C samples (column 5).
- Fig2a_RefractiveIndex_GradMZGO.txt : SiO2 content (%, column 1), effective refractive index of 1000 °C sample (column 2), effective refractive index of 800 °C sample (column 3), calculated product of the radiative decay rate and the quantity of ZGO for samples calcined at 1000 °C (column 4), measured product of the radiative decay rate and the quantity of ZGO for samples calcined at 1000 °C (column 5) and calculated product of the radiative decay rate and the quantity of ZGO for samples calcined at 800 °C (column 6).
- Fig2c_Lum.txt : Wavelength (nm, column 1), normalized Lum intensity of reference 100:0 1000 °C sample (column 2), normalized Lum intensity of 90:10 1000 °C sample (column 3), normalized Lum intensity of 100:0 800 °C sample (column 4), normalized Lum intensity of 90:10 800 °C sample (column 5).
- Fig2d_LumEnhancement.txt : SiO2 content (%, column 1), Lum enhancement of 1000 °C samples (column 2), standard deviation of Lum enhancement of 1000 °C samples (column 3) and Lum enhancement of 800 °C samples (column 4).
- Fig3a_PersL.txt : Wavelength (nm, column 1), normalized PersL intensity of reference 100:0 1000 °C sample (column 2), normalized PersL intensity of 90:10 1000 °C sample (column 3), normalized PersL intensity of 100:0 800 °C sample (column 4), normalized PersL intensity of 90:10 800 °C sample (column 5).
- Fig3b_PersLEnhancement.txt : SiO2 content (%, column 1), PersL enhancement of 1000 °C samples (column 2), standard deviation of PersL enhancement of 1000 °C samples (column 3), PersL enhancement of 800 °C samples (column 4), standard deviation of PersL enhancement of 800 °C samples (column 5).
- Fig4b_Kinetics_800°C.txt : Time (s, column 1), measured normalized PersL intensity of 100:0 800 °C sample (column 2), fitted normalized PersL intensity of 100:0 800 °C sample (column 3), measured normalized PersL intensity of 90:10 800 °C sample (column 4), fitted normalized PersL intensity of 90:10 800 °C sample (column 5), measured normalized PersL intensity of 80:20 800 °C sample (column 6), fitted normalized PersL intensity of 80:20 800 °C sample (column 7), measured normalized PersL intensity of 70:30 800 °C sample (column 8) and fitted normalized PersL intensity of 70:30 800 °C sample (column 9).
- Fig4c_Kinetics_1000°C.txt : Time (s, column 1), measured normalized PersL intensity of 100:0 1000 °C sample (column 2), fitted normalized PersL intensity of 100:0 1000 °C sample (column 3), measured normalized PersL intensity of 90:10 1000 °C sample (column 4), fitted normalized PersL intensity of 90:10 1000 °C sample (column 5), measured normalized PersL intensity of 80:20 1000 °C sample (column 6), fitted normalized PersL intensity of 80:20 1000 °C sample (column 7), measured normalized PersL intensity of 70:30 1000 °C sample (column 8) and fitted normalized PersL intensity of 70:30 1000 °C sample (column 9).
- Fig4d_BrightnessFactor_TrappingStrength_800°C.txt : SiO2 content (%, column 1), trapping strength parameter omega of 800 °C samples (column 2), brightness factor MZGO*Grad/Gtot of 800 °C samples (column 3) and standard deviation of brightness factor MZGO*Grad/Gtot of 800 °C samples (column 4).
- Fig4e_BrightnessFactor_TrappingStrength_1000°C.txt : SiO2 content (%, column 1), trapping strength parameter omega of 1000 °C samples (column 2), standard deviation of trapping strength parameter omega of 1000 °C samples (column 3), brightness factor MZGO*Grad/Gtot of 1000 °C samples (column 4) and standard deviation of brightness factor MZGO*Grad/Gtot of 1000 °C samples (column 5).
- Fig_S3a.txt : Ellipsometry spectra and fitting of ZGO:Cr film annealed at 1000 °C. Measurements were performed for the following incident angles: 50º,55º,60º,65º,70º. Wavelength in nm (column 1), delta in º (columns 2-6), psi in º (columns 7-11), fitted delta in º (columns 12-16), fitted psi in º (columns 17-21).
- Fig_S3b.txt : Ellipsometry spectra and fittings of 90:10 composite film annealed at 1000 °C. Measurements were performed for the following incident angles: 50º,55º,60º,65º,70º. Wavelength in nm (column 1), delta in º (columns 2-6), psi in º (columns 7-11), fitted delta in º (columns 12-16), fitted psi in º (columns 17-21).
- Fig_S3c.txt : Ellipsometry spectra and fittings of 80:20 composite film annealed at 1000 °C. Measurements were performed for the following incident angles: 50º,55º,60º,65º,70º. Wavelength in nm (column 1), delta in º (columns 2-6), psi in º (columns 7-11), fitted delta in º (columns 12-16), fitted psi in º (columns 17-21).
- Fig_S3d.txt : Ellipsometry spectra and fittings of 70:30 composite film annealed at 1000 °C. Measurements were performed for the following incident angles: 50º,55º,60º,65º,70º. Wavelength in nm (column 1), delta in º (columns 2-6), psi in º (columns 7-11), fitted delta in º (columns 12-16), fitted psi in º (columns 17-21).
- Fig_S3e.txt : Ellipsometry spectra and fittings of 60:40 composite film annealed at 1000 °C. Measurements were performed for the following incident angles: 50º,55º,60º,65º,70º. Wavelength in nm (column 1), delta in º (columns 2-6), psi in º (columns 7-11), fitted delta in º (columns 12-16), fitted psi in º (columns 17-21).
- Fig_S3f.txt : Ellipsometry spectra and fittings of 50:50 composite film annealed at 1000 °C. Measurements were performed for the following incident angles: 50º,55º,60º,65º,70º. Wavelength in nm (column 1), delta in º (columns 2-6), psi in º (columns 7-11), fitted delta in º (columns 12-16), fitted psi in º (columns 17-21).
- Fig_4a.txt : Transmission and reflection spectra and fittings of ZGO:Cr film annealed at 800 °C. Measurements were performed for the following incident angles: 6º,30º,50º. Wavelength in nm (column 1), reglectance R (columns 2-4), transmittance (columns 5-7), fitted reflectance (columns 8-10), fitted transmittance (columns 11-13).
- Fig_4b.txt : Transmission and reflection spectra and fittings of 80:20 composite film annealed at 800 °C. Measurements were performed for the following incident angles: 6º,30º,50º. Wavelength in nm (column 1), reglectance R (columns 2-4), transmittance (columns 5-7), fitted reflectance (columns 8-10), fitted transmittance (columns 11-13).
- Fig_4c.txt : Transmission and reflection spectra and fittings of 50:50 composite film annealed at 800 °C. Measurements were performed for the following incident angles: 6º,30º,50º. Wavelength in nm (column 1), reglectance R (columns 2-4), transmittance (columns 5-7), fitted reflectance (columns 8-10), fitted transmittance (columns 11-13)
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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