20 results on '"RADIATIVE transitions"'
Search Results
2. Synergistic enhancement of optical properties in erbium-doped borate glasses through copper nanoparticle incorporation.
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Ingle, Avinash, Shashikala, H.D., and Udayashankar, N.K.
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RARE earth oxides , *BORATE glass , *RADIATIVE transitions , *COPPER , *BRANCHING ratios - Abstract
The present study investigated the impact of incorporating copper nanoparticles (CuNPs) on the optical properties of erbium-doped borate glasses. Through melt-quenching and heat treatment techniques, glasses with varying Cu 2 O concentrations (x = 0–5 mol%) were synthesized. Physical and structural analyses revealed that Cu ions serve as effective network modifiers. They foster the formation of a greater proportion of BO 4 tetrahedra and thus enhancing glass homogeneity. Optical absorption spectra demonstrate a distinct modulation of Er3+ absorption bands with Cu 2 O embedding, indicating the formation of CuNPs, as validated by the emergence of surface plasmon resonance bands. This structural evolution results in a noticeable reduction in the bandgap energy, signifying improved semiconducting behavior. Judd-Ofelt analysis highlighted the profound influence of CuNPs on hypersensitive transitions, thereby affecting oscillator strength. Photoluminescence measurements revealed amplified emission in the visible red and near infrared (NIR) region, attributed to the synergistic effects of CuNPs and Er3+ ions, with 5 mol % Cu 2 O exhibiting the highest emission intensity. Analysis of the radiative properties validates the enhancement of the emission cross-section, gain bandwidth, optical gain and radiative transitions. These enhancements contribute to a notable increase in the branching ratio from 0.91 % to 5.41 % accompanied by an increase in the quantum efficiency from ∼79 % to ∼90 %. Moreover, decay analysis revealed a notable enhancement in lifetime from 3.03 ms to 15.74 ms, which is indicative of enhanced radiative transitions. Overall, the incorporation of CuNPs into erbium-doped borate glasses facilitates significant enhancements in physical, structural, and optical properties. This positions them as promising materials for a wide array of optoelectronic applications. This comprehensive study sheds light on the complex interplay between CuNPs and erbium-barium borate glasses, offering valuable insights for the development of advanced optoelectronic materials with enhanced performance and functionality. [Display omitted] [ABSTRACT FROM AUTHOR]
- Published
- 2024
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3. Structural and optical studies on various concentrations of Dy3+-doped lead fluoro-borotellurophosphate glasses for white light and solid-state light applications.
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D'Silva, A. Josuva, Maheshvaran, K., Lourduraj, A. J. Clement, and Rayappan, I. Arul
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CRYSTAL glass ,STIMULATED emission ,RADIATIVE transitions ,BRANCHING ratios ,OPTICAL properties ,SAMARIUM - Abstract
Dysprosium-doped lead fluoro-borotellurophosphate glasses with the chemical composition of (25-x) H
3 BO3 + 10TeO2 + 25P2 O5 + 10PbO + 08ZnF2 + 12NaF + 10Li2 CO3 + xDy2 O3 (x = 0.1, 0.25, 0.5, 1 & 1.5) were prepared by melt quenching technique. The structural and optical properties were studied to understand the behavior of Dy3+ ions with the local environment for photonic applications. The structural investigations were carried out through XRD, FTIR and SEM with EDS analysis. The absence of sharp peaks in the XRD pattern confirms the non-crystalline nature of the prepared glasses. The various functional groups of the composition were confirmed through FTIR. The surface morphology and the distribution of elements presented were observed through SEM with EDS. The optical behaviors were studied through UV–Vis-NIR, photoluminescence and chromaticity analysis. The JO intensity parameters Ωλ (λ = 2, 4, 6) were calculated, and the higher Ω2 value of BTPPZNL0.1D glasses indicates the asymmetry around Dy3+ ions. The radiative parameters like emission band position (λp ), effective band width (Δλeff ), radiative transition probability (A), stimulated emission cross section σ p E , and calculated and experimental branching ratios (βR ) were determined from emission analysis. The higher value of stimulated emission cross section σ p E for4 F9/2 →6 H13/2 transition suggested that BTPPZNL1.5D glass is suitable for laser application. The evaluated color coordinates of prepared glasses represent the capacity of white light emission under UV excitation. [ABSTRACT FROM AUTHOR]- Published
- 2023
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4. Examining the Spectroscopic and Thermographic Qualities of Er 3+ -doped Oxyfluoride Germanotellurite Glasses.
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Ryba-Romanowski, Witold, Komar, Jarosław, and Lisiecki, Radosław
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ABSORPTION spectra , *RADIATIVE transitions , *MOLECULAR spectra , *QUANTUM efficiency , *BRANCHING ratios - Abstract
Novel ternary fluoro-germano-tellurite (GTS) glasses doped with Er3+ ions with 0.5 mol% and 1.0 mol% were fabricated by a conventional melt and quenching method and investigated using methods of optical spectroscopy. The room-temperature absorption spectrum was recorded and analyzed to determine radiative transition rates, radiative lifetimes, and branching ratios of Er3+ luminescence. Decay curves of Er3+ luminesccence were recorded and analyzed. Temperature dependences of emission spectra and absorption spectra in the region from RT (room-temperature) up to 675 K were studied in detail. The contribution of competing radiative and nonradiative processes to the relaxation of luminescent levels of Er3+ was assessed. Absolute and relative sensitivity were established utilizing the comprehensive model based on thermally coupled 2H11/2/4S3/2 excited states of erbium. The high quantum efficiency of the first erbium-excited state and value of gain coefficient indicate that GTS:Er glass system can be considered as conceivable NIR (near infrared) laser material as well. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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5. Spectroscopic Studies of Ho3+-Doped SrF2 Crystal or Green and Red Laser Applications.
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Kumar, Ravinder and Joseph, David
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SOLID-state lasers , *BRANCHING ratios , *SINGLE crystals , *CRYSTAL structure , *RADIATIVE transitions - Abstract
Spectroscopic studies of Ho3+-doped SrF2 crystals were performed regarding applications in solid-state lasers. The crystal structure of the Ho:SrF2 crystal was investigated using single-crystal X-ray diffraction. SrF2 exists as a cubic structure with an Fm3m space group. A Raman shift of 288 cm–1 was observed for the Ho:SrF2 single crystal. SrF2 hosts with low-frequency vibrational modes are suitable for reducing nonradiative emissions while maximizing radiative emissions. The absorption spectrum was recorded in the visible region from 400 to 800 nm, yielding absorption lines at 416, 450, 468, 473, 484, 536, 638, and 643 nm. The fluorescence spectrum recorded at an excitation wavelength of 450 nm shows two emission bands at 546 and 656 nm, which correspond to green and red emission, respectively. The intensity parameters Ωλ (λ = 2, 4, and 6) were estimated using the Judd–Ofelt theory. For Ho:SrF2 single crystal, the calculated Ωλ are Ω2 = 0.14 × 10–20 cm2, Ω4 = 3.14 × 10–20 cm2, and Ω6 = 3.74 × 10–20 cm2. The radiative transition probabilities, radiative lifetimes, and branching ratios βR for Ho:SrF2 were determined using the Judd–Ofelt parameters. The 5
S 2 + 5F 4 → 5I 8 transition is more effective for population-building processes because of its lifetime (0.26 ms) and higher branching ratios (~82.86%). Ho:SrF2 is, therefore, a promising solid-state laser crystal for green and red spectral regions. [ABSTRACT FROM AUTHOR]- Published
- 2024
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6. Enhancement of the structure, optical, and spectroscopic properties of fluoroborosilicate glass doped with thulium.
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Marzouk, Samir Y. and Hammad, Ahmed H.
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THULIUM ,THULIUM ions ,BOROSILICATES ,RADIATIVE transitions ,LIGHT absorption ,BRANCHING ratios - Abstract
Glass composition of (0.15-x)LiF–0.15NaF–0.01Al
2 O3 –0.24SiO2 –0.45B2 O3 –xTm2 O3 , in which x varies from 0.01 to 0.08, has been prepared by melt-annealing technique. The glass density values increased as thulium content increases from 2.359 to 2.735 g/cm3 . The structure of glass showed the presence of trigonal BO3 , O2 B–F, tetrahedral BO4 , O3 B–F units, Si–O–Si, B–O–Si, and B–O–B linkages. The optical properties of the prepared glass were investigated. The optical absorption spectra revealed four characteristic bands in the ultraviolet and near-infrared regions for thulium ions. Judd–Ofelt parameters such as Ω2 , Ω4 , and Ω6 were calculated and took the order of Ω2 > Ω6 > Ω4 . The radiative transition probability, branching ratio, and radiative lifetime were deduced from the Judd–Ofelt parameters. Moreover, the optical transition, refractive index, and phonon energy were calculated to show the effect of thulium content on borosilicate glass. [ABSTRACT FROM AUTHOR]- Published
- 2021
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7. Dy3+: B2O3–Al2O3–ZnO–Bi2O3–BaO–M2O (M = Li; Na; and K) glasses: Judd–Ofelt analysis and photoluminescence investigation for WLED applications.
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Lakshminarayana, G., Wagh, Akshatha, Lira, A., Kityk, I. V., Lee, Dong-Eun, Yoon, Jonghun, and Park, Taejoon
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GLASS analysis ,ALKALI metal ions ,RADIATIVE transitions ,OSCILLATOR strengths ,PHOTOLUMINESCENCE ,BRANCHING ratios ,BISMUTH ,SAMARIUM - Abstract
Authors aim to study multicomponent barium bismuth borate glasses doped with Dy
3+ (1 mol%) for white light-emitting diodes (WLEDs) application. All samples, synthesized through melt-quench approach, were characterized by XRD, optical absorption, excitation, emission, and decay lifetimes. Oscillator strengths and Judd–Ofelt intensity parameters (Ω2 , Ω4 , Ω6 ) for all glasses were computed from absorption spectra and further, radiative emission transition probability (AR ), branching ratio (βR ), and radiative lifetime (τR ) were estimated for Dy3+ ion various excited states using J–O parameters. Upon 350 nm excitation,4 I15/2 →6 H15/2 [454 nm (blue)],4 F9/2 →6 H15/2 [483 nm (blue)],4 F9/2 →6 H13/2 [575 nm (yellow)], and4 F9/2 →6 H11/2- [663 nm (red)] emission transitions were observed among which4 F9/2 →6 H13/2 transition exhibits the highest intensity. Dy3+ : Li glass showed relatively higher PL intensity and quantum efficiency than Dy3+ : Na and Dy3+ : K samples. Calculated CIE chromaticity (x = ~ 0.35, y = ~ 0.39) coordinates (λex. : 350 nm) and CCTs (4749‒4890 K) proclaimed overall neutral white light emission from all samples, implying their suitability for WLED applications. Decay lifetimes (τexp ) were determined for Dy3+ :4 F9/2 →6 H13/2 transition. Additionally, stimulated emission cross-section ( σ p E ) and gain bandwidth ( σ p E × Δλeff ) were calculated for respective blue and yellow emission transitions. [ABSTRACT FROM AUTHOR]- Published
- 2020
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8. Spectroscopy Study of Sm3+ Doped Fluorosilicate Glasses for Orange Emission Solid-State Device Application.
- Author
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Khan, I., Rooh, G., Rajaramakrishna, R., Sirsittipokakun, N., Kim, H. J., Ruangtaweep, Y., and Kaewkhao, J.
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STIMULATED emission , *RADIATIVE transitions , *GLASS transition temperature , *BRANCHING ratios , *OSCILLATOR strengths , *QUANTUM efficiency , *VISIBLE spectra - Abstract
Glass samples with formula as Li2O–BaO–GdF3–SiO2:Sm2O3 were fabricated by melt quenching method. Their optical, physical and luminescence properties were studied, for their potential applications in photonic device working in visible region. The Sm3+ ions and nearby ligands bonding nature were determined from bonding parameters (δ) that in turn were calculated from LGF absorption spectra. Oscillator strength of different absorption bands and Judd–Ofelt (JO) parameters (Ωλ (λ = 2, 4, 6)) were measured. JO-parameters and refractive index have been used to valuate various radiative properties of Sm3+ ions emission transitions in prepared glasses to explore their potential application as visible lasers. Furthermore, the emission was studied by exciting the LGF glass samples with different wavelengths (λex = 275, 402 nm). The orange to red ratios at different wavelengths (λex = 275 nm and X-ray) were evaluated to measure the Sm3+-ions local disorder in the glass network. The decreasing trend in experimental decay time (τexp) with Sm3+-ion concentration increasing was observed due to energy transfer. Best fit for the prepared glass, when studied in the light of Inokuti–Hirayama model was obtained for S = 6 indicating dipole–dipole type of energy transfer. The intense visible (orange) emission, high stimulated emission cross-section (σe), branching ratios (βR), radiative transition probability (AR), and reasonable quantum efficiency were determined for transition from 4G5/2 to 6H7/2 in glass. This suggests Sm3+ doped glass shows potential use for development of devices (laser and photonic) working in visible (orange) region. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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9. Pr3+-Doped Strontium–Aluminum–Bismuth–Borate Glasses for Laser Applications.
- Author
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Naidu, M. Dhamodhara and Ratnakaram, Y. C.
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STIMULATED emission , *RADIATIVE transitions , *BRANCHING ratios , *MOLECULAR spectra , *GLASS , *CHROMATICITY - Abstract
The chemical composition of Pr3+-doped strontium–aluminum–bismuth–borate glasses with different concentrations, that is, (50 – x)B2O3 + 20Bi2O3 + 7AlF3 + 8SrO + 15SrF2 + xPr2(CO3)3 (where x = 0.1, 0.5, 1.0, and 1.5 mol.%), have been prepared by the melt quenching technique. XRD, SEM, and EDS studies reveal the structural and amorphous properties of the prepared glasses. Different borate groups are analyzed by FTIR measurements. Judd–Ofelt (J–O) intensity parameters, Ωλ (λ = 2, 4, and 6) are calculated from the absorption spectrum to identify the nature of Pr3+ ions with their surrounding ligands. Using the J–O parameters, the radiative properties such as radiative transition probabilities AR and radiative lifetimes τcal are evaluated for various excited transitions of Pr3+ ions. Stimulated emission cross sections σ p E and branching ratios βR for the emission transitions are evaluated by the photoluminescence spectra. The higher values of σ p E and βR are identified for the emission transitions 3P0 → 3H4 and 1D2 → 3H4 of SABiBPr15 and SABiBPr01 glasses; these glasses are suitable for light emitting materials. The chromaticity color coordinates are calculated to find the average color of the emission spectra. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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10. Sm3+-doped oxyfluorotellurite glasses - spectroscopic, luminescence and temperature sensor properties.
- Author
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Klimesz, Barbara, Lisiecki, Radosław, and Ryba-Romanowski, Witold
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LUMINESCENCE , *TEMPERATURE sensors , *GLASS , *DIFFERENTIAL thermal analysis , *RADIATIVE transitions , *OSCILLATOR strengths , *BRANCHING ratios - Abstract
Abstract The thermal and optical properties of oxyfluorotellurite (65-x)TeO 2 -20ZnF 2 -12PbO-3Nb 2 O 5 -xSm 2 O 3 (x = 0.5, 2 and 5) glass systems were investigated. Glass thermal stability were monitored by differential thermal analysis (DTA) and adequate thermal stability criteria ΔT, H' and S were determined. It was shown that the thermal stability of the investigated materials increases with the increasing of samarium ions content. The absorption and emission spectra of Sm3+ ions in oxyfluorotellurite glass were recorded in the wide spectral range from UV to NIR. Based on the Judd-Ofelt (J–O) procedure oscillator strengths, phenomenological Judd-Ofelt intensity parameters Ω 2,4,6, radiative transition probabilities, branching ratios and radiative lifetimes of luminescent levels were determined. The luminescence decay curves of the 4G 5/2 (Sm3+) excited state were recorded for three different concentrations of Sm3+ and corresponding experimental lifetimes were determined. Photoluminescence emission spectra were measured in the temperature range from 300 K up to 725 K to evaluate the materials under study as luminescent temperature sensor. Highlights • (65-x)TeO2-20ZnF2-12PbO-3Nb2O5-xSm2O3 (x = 0.5, 2, 5 mol%) glasses were prepared. • Thermal properties of glasses were analyzed as a function the Sm3+ concentrations. • The optical properties of Sm3+ ions in oxyfluorotellurite glass were assessed. • The materials under study were evaluated as luminescent temperature sensors. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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11. Enhanced luminescence at 2.88 and 2.04 μm from Ho3+/Yb3+ codoped low phonon energy TeO2–TiO2–La2O3 glass.
- Author
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Gupta, Gaurav, Balaji, Sathravada, Biswas, Kaushik, and Annapurna, Kalyandurg
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LUMINESCENCE , *PHONONS , *STIMULATED emission , *BRANCHING ratios , *RADIATIVE transitions , *GLASS - Abstract
The high phonon energy and short infrared cut-off wavelength of conventional oxide glass (or crystal) hosts are the limitations to achieve mid-infrared (MIR, λ≥2.5μm) luminescence. In present study, the luminescence performance of low phonon and non-conventional TeO2-TiO2-La2O3-based glass (TTL) host doped with Ho3+ and Ho3+/Yb3+ has been investigated, for visible to MIR range. The MIR emission band with peak at 2.88μm (Ho3+:5I6→5I7) and NIR band at 2.04μm (Ho3+:5I7→5I8) has been realized from Ho3+ singly doped TTL glass due to low phonon energy and extended transmission window of the host. Intensity of MIR and NIR emission bands have enhanced significantly in Ho3+/Yb3+: TTL glass under Yb3+ excitation, signifying an efficient Yb3+→Ho3+ energy transfer. The Judd-Ofelt analysis, on Ho3+ absorption characteristics reveals relatively better radiative transition probability (34.4s−1) and branching ratio (10.5%), which is associated to Ho3+:5I6→5I7 transition. The effective bandwidth of 2.88μm emission band is 180nm, with stimulated emission cross-section is 4.26×10-21cm2 and its gain bandwidth has been evaluated as 7.67×10-26cm3. For 2.04μm (Ho3+:5I7→5I8) emission band, the effective bandwidth of 160.5nm and gain bandwidth of 7.26×10-26cm3 have been accomplished. The non-resonant Förster-Dexter method has been applied to Ho3+/Yb3+: TTL glass on emission (donor, Yb3+) and absorption (acceptor, Ho3+) cross sections. The evaluated donor-donor (CDD) and donor-acceptor (CDA) energy transfer micro-parameters are 1.02×10-38 and 5.88×10-41cm6/s respectively while, maximum energy transfer efficiency has been 80%. In concise, Ho3+/Yb3+ codoped TeO2–TiO2–La2O3 glass host has revealed its potential for MIR to NIR photonic applications. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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12. Experimental radiative lifetimes, branching fractions, and oscillator strengths of some levels in Co I.
- Author
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Xinghao Wang, Qi Yu, Qiu Li, Yang Gao, and Zhenwen Dai
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RADIATIVE transitions , *BRANCHING ratios , *LASER-induced fluorescence , *EMISSION spectroscopy , *OSCILLATOR strengths - Abstract
The radiative lifetime measurements by the time-resolved laser-induced fluorescence technique are reported for 24 levels of Co I with the energy range of 283 45.86-55 922.3 cm-1, amongst which the lifetimes of 20 levels are reported for the first time. The branching fraction measurements by the emission spectrum of a hollow cathode lamp were performed for 11 levels of them together with other two levels reported in the literature, and branching fractions of 39 transitions were obtained. By combining them with lifetime values, the transition probabilities and absolute oscillator strengths of these lines were determined. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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13. Observation of the [formula omitted] decay.
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RADIOACTIVE decay , *LUMINESCENCE , *LARGE Hadron Collider , *STANDARD model (Nuclear physics) , *RADIATIVE transitions , *PHYSICS experiments , *STATISTICAL physics , *BRANCHING ratios - Abstract
The Λ b 0 → Λ ϕ decay is observed using data corresponding to an integrated luminosity of 3.0 fb − 1 recorded by the LHCb experiment. The decay proceeds at leading order via a b → s s ‾ s loop transition and is therefore sensitive to the possible presence of particles beyond the Standard Model. A first observation is reported with a significance of 5.9 standard deviations. The value of the branching fraction is measured to be ( 5.18 ± 1.04 ± 0.35 − 0.62 + 0.67 ) × 10 − 6 , where the first uncertainty is statistical, the second is systematic, and the third is related to external inputs. Triple-product asymmetries are measured to be consistent with zero. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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14. Optical and radiative properties of Nd3+-doped lead tellurite borate glasses.
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Shigihalli, N.B., Rajaramakrishna, R., and Anavekar, R.V.
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OPTICAL properties of borate glass , *DIFFERENTIAL scanning calorimetry , *AMORPHOUS substances , *X-ray diffraction measurement , *ULTRAVIOLET-visible spectroscopy , *RADIATIVE transitions , *BRANCHING ratios , *LASERS , *OPTICAL materials - Abstract
Glass samples of composition (in mol%) 20PbO-20TeO2-(60 - x)B2O3- xNd2O3 ( x = 0, 1, 2, 3, 4) were prepared by melt quenching. The glassy nature of as-quenched samples was established via differential scanning calorimetry. The amorphous nature of the glasses was confirmed via powder X-ray diffraction measurements. Judd-Ofelt (JO) analysis based on UV-visible absorption spectra was performed to determine JO parameters Ωλ ( λ = 2, 4, 6). The observed trend is Ω2 > Ω6 > Ω4. The large value of Ω2 indicates the presence of covalent bonding between the Nd3+ ions and the surrounding ligands. Radiative properties, such as radiative transition probabilities, branching ratios, and radiative lifetimes are estimated. The glass samples have relatively high branching ratio, and their emission ( Aem) to excited state absorption ( AESA) intensity ratio is higher than one for the 4F3/2 → 4I11/2 transition, indicating that the prepared glasses may have potential laser applications. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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15. Spectroscopic properties of Pr3+:SrMoO4 crystal
- Author
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Cao, Jiafeng, Wang, Yan, Ma, Xinghua, Li, Jianfu, Zhu, Zhaojie, You, Zhenyu, Yang, Fugui, Sun, Chengli, Cao, Ting, Ji, Yuexia, and Tu, Chaoyang
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METAL crystals , *CRYSTAL optics , *FLUORESCENCE spectroscopy , *RADIATIVE transitions , *BRANCHING ratios , *QUANTUM efficiency , *QUANTUM chemistry , *SOLID-state lasers - Abstract
Abstract: A Pr3+-doped SrMoO4 single crystal has been grown successfully by the Czochralski technique. The absorption spectra, fluorescence spectra, and fluorescence decay curves have been measured at room temperature. The spectroscopic parameters, including spectroscopic parameters Ω t (t =2,4,6), radiative transition probabilities, radiative lifetimes and branching ratios were determined according to the standard and modified Judd–Ofelt theories. The stimulated emission cross-sections, the fluorescence lifetimes and the quantum efficiency of Pr3+ ions in SrMoO4 were obtained. This study implies that Pr3+:SrMoO4 is an attractive candidate for solid-state laser medium. [Copyright &y& Elsevier]
- Published
- 2011
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16. Fast-ion-beam laser-induced-fluorescence measurements of spontaneous-emission branching ratios and oscillator strengths in Sm II.
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Rehse, S. J., Li, R., Scholl, T. J., Sharikova, A., Chatelain, R., Holt, R. A., and Rosner, S. D.
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OSCILLATOR strengths , *MONOCHROMATORS , *SAMARIUM isotopes , *DOPPLER effect , *RADIATIVE transitions , *BRANCHING ratios , *HARTREE-Fock approximation , *FLUORESCENCE , *SPECTRUM analysis - Abstract
We measured the spontaneous-emission branching ratios of 69 levels in Sm II selectively populated via single-frequency laser excitation of a 10 keV ion beam. The levels studied had term energies up to 29 600 cm–1, and decay branches with spontaneous emission in the range 250–850 nm were detected. The experimental accuracy was in the range of 10%. We used these branching ratios along with our previously determined radiative lifetimes to infer transition probabilities and oscillator strengths for 608 transitions in the wavelength range 363–771 nm, which are useful for stellar abundance determinations.PACS Nos.: 32.70.Cs, 95.30.Ky [ABSTRACT FROM AUTHOR]
- Published
- 2006
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17. Luminescence Properties and Judd–Ofelt Analysis of Various ErF 3 Concentration-Doped BaF 2 Crystals.
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Racu, Andrei, Stef, Marius, Buse, Gabriel, Nicoara, Irina, and Vizman, Daniel
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LUMINESCENCE , *CRYSTAL optics , *RADIATIVE transitions , *CRYSTALS , *BRANCHING ratios - Abstract
The influence of erbium ion concentration on the optical properties of BaF2:ErF3 crystals was investigated. Four ErF3 concentration (0.05, 0.08, 0.15 and 0.5 mol% ErF3)-doped BaF2 crystals were obtained using the Bridgman technique. Room temperature optical absorption in the 250–850 nm spectral range was measured, and the photoluminescence (PL) and decay times were also investigated. The Judd–Ofelt (JO) approximation was used, taking into account four absorption peaks (at 377, 519, 653 and 802 nm). The JO intensity parameters, Ωt (t = 2, 4, 6), were calculated. The influence of the ErF3 concentration on the JO parameters, branching ratio, radiative transition probability and radiative lifetime were studied. The obtained results were compared with measured values and with those reported in the literature. Under excitation at 380 nm, the well-known green (539 nm) and red (668 nm) emissions were obtained. The calculated and experimental radiative lifetimes were in millisecond range for green and red emissions. The intensity of the PL spectra varied with the Er3+ ion concentration. The emission intensity increased linearly or exponentially, depending on the ErF3 concentration. Under excitation at 290 nm, separate to the green and red emissions, a new UV emission band (at 321 nm) was obtained. Other research has not reported the UV emission or the influence of ErF3 concentration on emission behavior. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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18. Titania nanoparticles embedded Er3+-Sm3+ co-doped sulfophosphate glass: Judd-Ofelt parameters and spectroscopic properties enhancement.
- Author
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Ahmadi, Fahimeh, Ebrahimpour, Zeinab, and Asgari, Asghar
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TELLURITES , *PHOSPHATE glass , *NANOPARTICLES , *STIMULATED emission , *RADIATIVE transitions , *GLASS , *BRANCHING ratios - Abstract
The conventional melt quenching method was used to synthesis erbium and samarium ions co-doped sulfophosphate glasses containing TiO 2 nanoparticles with the molar compositions of (58.0-x)P 2 O 5 -20.0MgO-20.0ZnSO 4 -1.0Sm 2 O 3 -1.0Er 2 O 3 -xTiO 2 with x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0 mol%. The X-ray diffraction (XRD) technique was applied to verify that the nature of fabricated glass samples is of amorphous type. Judd-Ofelt (JO) intensity (Ω i) parameters were determined through spectral data provided in the investigations conducted on the optical absorption. The applied JO parameterization illustrates the covalency related to rare-earth (RE) ions and ligands. For some given lasing levels, the radiative parameters were estimated including branching ratios (β R), radiative lifetimes (τ R), and radiative transition probabilities (A). The photoluminescence spectra provided in some studies are used to evaluate the stimulated emission cross-sections (σ p E) for some important lasing transitions including 4G 5/2 → 6H 5/2 , 4G 5/2 → 6H 7/2 , and 4G 5/2 → 6H 9/2. The determined radiative parameters are potential options as a candidate for lasing. • Erbium and samarium ions co-doped sulfophosphate glasses containing TiO 2 nanoparticles glasses were prepared. • The average size of the TNPs was obtained 18 ± 1 nm. • Intensified Raman signal can be related to the contribution of SPR that results in an enlarged local electric field. • PMZSE0.8Ti glass sample can be considered as an effective option in the photonic applications. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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19. Thermosensitive Tm3+/Yb3+ co-doped oxyfluorotellurite glasses – spectroscopic and temperature sensor properties.
- Author
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Klimesz, Barbara, Lisiecki, Radosław, and Ryba-Romanowski, Witold
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TEMPERATURE sensors , *LASER cooling , *DIFFERENTIAL thermal analysis , *GLASS , *RADIATIVE transitions , *OSCILLATOR strengths , *BRANCHING ratios , *LUMINESCENCE measurement - Abstract
Oxyfluorotellurite (65- x)TeO 2 –20ZnF 2 –12PbO–3Nb 2 O 5 – x Tm 2 O 3 (x = 0.5, 2 and 5) and (65- x - y)TeO 2 –20ZnF 2 –12PbO–3Nb 2 O 5 – x Tm 2 O 3 – y Yb 2 O 3 (x = 0.5, y = 2 and x = 0.5, y = 5) glass systems were manufactured. Glass thermal stability was examined by means of differential thermal analysis (DTA) and some thermal stability criteria ΔT , H ' and S were determined. Absorption spectrum was utilized to prepare Judd-Ofelt (J-O) calculations and consequently oscillator strengths, intensity parameters Ω 2,4,6 , radiative transition probabilities, branching ratios and radiative lifetimes of luminescent levels were estimated. Emission spectra and luminescence decay curves were measured as a function of temperature in the 300–625 K range. Based on the upconversion luminescence of Tm3+ the optical temperature sensor qualities have been evaluated for Tm3+/Yb3+ co-doped sample. The fluorescence intensity ratio (FIR) between transitions 700 nm (Tm3+:3F 2,3 → 3H 6)/800 nm (Tm3+:3H 4 → 3H 6) for 975 nm excitation and 700 nm (Tm3+:3F 2,3 → 3H 6)/470 nm (Tm3+:1G 4 → 3H 6) for 803 nm excitation were determined and an adequate relative thermal sensitivity S was estimated. The significant value of relative thermal sensitivity 1.12 %K−1 was determined when NIR Yb3+ and Tm3+ emission bands were analyzed, however. Effective emission cross section was calculated for 3F 4 → 3H 6 potential laser transition of thulium around 1.9 μm in single-doped Tm3+ glass. Furthermore, effect of temperature on down-converted and up-converted thulium and ytterbium emission and on relaxation dynamic of involved excited states was studied in details. • Oyfluorotellurite glasses singly-doped and co-doped Tm3+ and Yb3+ were prepared. • Thermal and optical properties of tested materials were determined. • Thermal properties of glasses depend on the Tm3+/Yb3+ ions concentrations. • Investigated materials have advantageous properties for NIR optical gain. • TZPN glasses activated with RE3+ ions can be used in luminescence thermometry. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
20. Structural, photoluminescent properties and Judd-Ofelt analysis of Eu3+-activated CaF2 nanocubes.
- Author
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Cantelar, Eugenio, Sanz-García, Juan Antonio, Sanz-Martín, Adrián, Muñoz Santiuste, Juan Enrique, and Cussó, Fernando
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LATTICE constants , *LOGNORMAL distribution , *RADIATIVE transitions , *LUMINESCENCE , *RIETVELD refinement , *BRANCHING ratios , *RARE earth metals - Abstract
Eu3+-doped CaF 2 nanocubes with variable europium concentration, [Eu3+] = 0, 0.6, 1.3, 1.7, 2.2 and 5.4 mol%, have been synthesized by a direct precipitation route. It has been found that, within this concentration range, the nanoparticles present the fluoride-type crystalline structure and the characteristic cubic shape of CaF 2 crystals. The nanoparticle size follows a log-normal distribution with a mean value decreasing with the Eu3+ content. Rietveld refinement has been performed to calculate the lattice parameter and crystallite size. Eu3+ concentration affects both parameters giving rise to an increase in the lattice parameter and a reduction of crystallite size. The luminescent properties of Eu3+ ions in these nanostructures have been investigated under CW and pulsed excitation. A Judd-Ofelt analysis, as function of the Eu3+ content, has been performed to determine the transition probabilities, radiative lifetimes and branching ratios of the 5D 0 emitting level. It was found that Ω 2 and Ω 4 Judd-Ofelt intensity parameters are dependent on the doping level, showing an evolution that indicates a decrease in the Eu3+ site local symmetry with increasing Eu3+ concentration. Finally, it has been observed that the characteristic luminescence decay time of the 5D 0 manifold is reduced with increasing Eu3+ concentration. This effect is partially due to an increase of radiative transition probability, associated with a reduction in the local symmetry of the lanthanide ions, and also to the occurrence of concentration quenching effects. Image 1 • High CaF 2 :Eu3+ nanocubes. • Eu3+ excellent probe to link structural and luminescence properties. • Judd-Ofelt analysis dependent on structural properties. • Optimum doping level at 2 mol% europium concentration. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
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