1
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Larsson ED, Veryazov V. An embedded cluster CASPT2 study of the Ce:YVO4 spectrum. J Chem Phys 2023; 159:114117. [PMID: 37724731 DOI: 10.1063/5.0159246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Accepted: 08/28/2023] [Indexed: 09/21/2023] Open
Abstract
Multiconfigurational theory, in combination with the embedded cluster approach, is a precise and ab initio approach to describe the electronic structure of solids. In this work, the spectrum of a Ce(III) dopant in YVO4 has been studied by complete active space perturbation theory of the second order (CASPT2), with the host material represented as a set of ab initio model potentials and point-charges. We assess the sensitivity of the spectrum to the size of both the embedded cluster size as well as the size of the electronic basis set. A comparison of our best computational model with experimental results shows that the embedding approach is robust and can accurately model the spectrum of low-concentration dopants in complex host materials.
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Affiliation(s)
- Ernst D Larsson
- Division of Theoretical Chemistry, Lund University, Lund 22100, Sweden
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Valera Veryazov
- Division of Theoretical Chemistry, Lund University, Lund 22100, Sweden
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2
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Shyichuk A, Krośnicki M. Electron Trap Depths in Cubic Lutetium Oxide Doped with Pr and Ti, Zr or Hf─From Ab Initio Multiconfigurational Calculations. J Phys Chem A 2023. [PMID: 37196340 DOI: 10.1021/acs.jpca.2c07979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
We propose a universal approach to model intervalence charge transfer (IVCT) and metal-to-metal charge transfer (MMCT) transitions between ions in solids. The approach relies on already well-known and reliable ab initio RASSCF/CASPT2/RASSI-SO calculations for a series of emission center coordination geometries (restricted active space self-consistent field, complete active space second-order perturbation theory, and restricted active space state interaction with spin-orbit coupling). Embedding with ab initio model potentials (AIMPs) is used to represent the crystal lattice. We propose a way to construct the geometries via interpolation of the coordinates obtained using solid-state density functional theory (DFT) calculations for the structures where the activator metal is at specific oxidation (charge) states of interest. The approach thus takes the best of two worlds: the precision of the embedded cluster calculations (including localized excited states) and the geometries from DFT, where the effects of ionic radii mismatch (and eventual nearby defects) can be modeled explicitly. The method is applied to the Pr activator and Ti, Zr, Hf codopants in cubic Lu2O3, in which the said ions are used to obtain energy storage and thermoluminescence properties. Electron trap charging and discharging mechanisms (not involving a conduction band) are discussed in the context of the IVCT and MMCT role in them. Trap depths and trap quenching pathways are analyzed.
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Affiliation(s)
- Andrii Shyichuk
- Faculty of Chemistry, University of Wrocław, ul. F. Joliot-Curie 14, 50-383 Wrocław, Poland
| | - Marek Krośnicki
- Institute of Theoretical Physics and Astrophysics, Faculty of Mathematics, Physics and Informatics, University of Gdańsk, ul. Wita Stwosza 57, 80-308 Gdańsk, Poland
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3
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Sun H, Jiang H. Combined
DFT
and wave function theory approach to excited states of lanthanide luminescent materials: A case study of
LaF
3
:Ce
3+. J CHIN CHEM SOC-TAIP 2022. [DOI: 10.1002/jccs.202200348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Huai‐Yang Sun
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering Peking University Beijing PR China
| | - Hong Jiang
- Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering Peking University Beijing PR China
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4
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Ayman MT, Chung WJ, Lee H, Yoon DH. Fabrication and photoluminescence of γ-AlON:Sm and Yb. Ann Ital Chir 2022. [DOI: 10.1016/j.jeurceramsoc.2021.12.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
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5
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Kitagawa Y, Ueda J, Xu J, Nakanishi T, Takeda T, Hirosaki N, Tanabe S. Deep-red to near-infrared luminescence from Eu 2+-trapped exciton states in YSiO 2N. Phys Chem Chem Phys 2022; 24:4348-4357. [PMID: 35108722 DOI: 10.1039/d1cp05242j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The valence state of Eu ions doped in inorganic compounds is easily influenced by the synthesizing conditions. In this study, X-ray absorption spectroscopy revealed that almost half of Eu ions incorporated in the YSiO2N host were reduced into the divalent state through the sintering process at 1600 °C under a N2 gas atmosphere without any annealing processes. The prepared Eu2+/3+-doped YSiO2N sample showed anomalous deep-red to near-infrared luminescence below 300 K under violet light illumination, whose luminescent properties are discussed through detailed spectroscopic analyses. In the photoluminescence spectra at 4 K, the broad luminescence band ranging from 550 to 1100 nm with a large Stokes shift of 5677 cm-1 was observed, assigned to the recombination emission related to the Eu2+-trapped exciton state. The temperature dependence of luminescence lifetime suggests that the thermal quenching of Eu2+-trapped exciton luminescence takes place through complicated processes in addition to thermal ionization. The energy diagrams based on the spectroscopic results indicate that Eu2+-trapped exciton luminescence in the YSiO2N:Eu2+/3+ sample was observed because all the Eu2+: 5d excited levels are degenerated with the host conduction band, and the relatively stable Eu2+-trapped exciton state in the Y3+ sites is formed just below the conduction band bottom. A comprehensive discussion on the deep-red to near-infrared luminescence in the YSiO2N host could give new insights into the mechanism of Eu2+-trapped exciton luminescence in Y3+ sites, which has potential in near-infrared emitting devices.
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Affiliation(s)
- Yuuki Kitagawa
- Department of Interdisciplinary Environment, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan.
| | - Jumpei Ueda
- Department of Interdisciplinary Environment, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan.
| | - Jian Xu
- International Center for Young Scientists (ICYS), National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0044, Japan
| | - Takayuki Nakanishi
- Luminescent Materials Group, National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0044, Japan
| | - Takashi Takeda
- Luminescent Materials Group, National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0044, Japan
| | - Naoto Hirosaki
- Luminescent Materials Group, National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0044, Japan
| | - Setsuhisa Tanabe
- Department of Interdisciplinary Environment, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan.
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6
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Püschel S, Mauerhoff F, Kränkel C, Tanaka H. Solid-state laser cooling in Yb:CaF 2 and Yb:SrF 2 by anti-Stokes fluorescence. OPTICS LETTERS 2022; 47:333-336. [PMID: 35030612 DOI: 10.1364/ol.449115] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 12/14/2021] [Indexed: 06/14/2023]
Abstract
We report on the first example, to the best of our knowledge, of solid-state laser cooling in ytterbium-doped CaF2 and SrF2 crystals by anti-Stokes fluorescence. The crystals were grown by the Czochralski method in a fluorine-rich atmosphere to prevent the formation of divalent ytterbium ions. Using laser-induced thermal modulation spectroscopy (LITMoS), we find the cooling efficiencies for both crystals to be higher than 3% at room temperature. According to model calculations performed using temperature-dependent spectroscopic data, these crystals can be cooled to temperatures as low as 150 K when excited at around 1030 nm.
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7
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Strek W, Stefanski M, Hanulia T, Tomala R, Wiewiorski P. Laser induced visible and infrared emission of a tungsten filament. OPTICS EXPRESS 2021; 29:27291-27297. [PMID: 34615147 DOI: 10.1364/oe.433852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 07/15/2021] [Indexed: 06/13/2023]
Abstract
The measurements of laser induced emission (LIE) of a tungsten filament upon irradiation with the focused beam of a CW IR laser diode are reported. It was found that the emission occurred in visible and infrared range. The influence of the applied DC electric field significantly affected the intensity of LIE of the tungsten filament. The origin of LIE is discussed in terms of multiphoton ionization of tungsten W+ atoms assisted by light emission due to the intervalence charge transfer in the tungsten hybrid domain (W, W+).
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8
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Joos JJ, Neefjes I, Seijo L, Barandiarán Z. Charge transfer from Eu2+ to trivalent lanthanide co-dopants: Systematic behavior across the series. J Chem Phys 2021; 154:064704. [DOI: 10.1063/5.0037992] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Affiliation(s)
- Jonas J. Joos
- LumiLab, Department of Solid State Sciences, Ghent University, B-9000 Gent, Belgium
| | - Ivo Neefjes
- Department of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001 Leuven, Belgium
| | - Luis Seijo
- Departamento de Química, Instituto Universitario de Ciencia de Materiales Nicolás Cabrera, and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Zoila Barandiarán
- Departamento de Química, Instituto Universitario de Ciencia de Materiales Nicolás Cabrera, and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, 28049 Madrid, Spain
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9
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Broadband infrared LEDs based on europium-to-terbium charge transfer luminescence. Nat Commun 2020; 11:3647. [PMID: 32686683 PMCID: PMC7371692 DOI: 10.1038/s41467-020-17469-x] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 06/24/2020] [Indexed: 11/21/2022] Open
Abstract
Efficient broadband infrared (IR) light-emitting diodes (LEDs) are needed for emerging applications that exploit near-IR spectroscopy, ranging from hand-held electronics to medicine. Here we report broadband IR luminescence, cooperatively originating from Eu2+ and Tb3+ dopants in CaS. This peculiar emission overlaps with the red Eu2+ emission, ranges up to 1200 nm (full-width-at-half-maximum of 195 nm) and is efficiently excited with visible light. Experimental evidence for metal-to-metal charge transfer (MMCT) luminescence is collected, comprising data from luminescence spectroscopy, microscopy and X-ray spectroscopy. State-of-the-art multiconfigurational ab initio calculations attribute the IR emission to the radiative decay of a metastable MMCT state of a Eu2+-Tb3+ pair. The calculations explain why no MMCT emission is found in the similar compound SrS:Eu,Tb and are used to anticipate how to fine-tune the characteristics of the MMCT luminescence. Finally, a near-IR LED for versatile spectroscopic use is manufactured based on the MMCT emission. Broadband near-infrared (IR) light-emitting diodes (LEDs) are desirable for smart devices and bio-imaging applications, but the efficiency is limited by the phosphor materials. The authors report broadband emission in Eu-Tb co-doped CaS due to metal-to-metal charge transfer between dopants, and build a broadband near-IR LED with output surpassing the state of the art.
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10
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Stefanski M, Lukaszewicz M, Hreniak D, Strek W. Impact of the synthesis procedure on the spectroscopic properties of anti-Stokes white emission obtained from Sr2CeO4 phosphor. J Photochem Photobiol A Chem 2019. [DOI: 10.1016/j.jphotochem.2019.111855] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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11
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Joos JJ, Seijo L, Barandiarán Z. Direct Evidence of Intervalence Charge-Transfer States of Eu-Doped Luminescent Materials. J Phys Chem Lett 2019; 10:1581-1586. [PMID: 30884232 DOI: 10.1021/acs.jpclett.9b00342] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Direct evidence is given for the existence of intervalence charge transfer (IVCT) states of Eu2+/Eu3+ pairs in Eu-doped CaF2, SrF2, and BaF2. They are detected in diffuse reflectance spectra. In doped materials, IVCT states, in which an electron transfer occurs between two metal sites differing only in oxidation state, are rather difficult to observe because the absorption bands are extremely broad and flat, their intensity is low, and no emission follows the IVCT absorptions. Their assignment as IVCT states is provided by state-of-the-art multiconfigurational ab initio calculations. Although IVCT states of lanthanide-doped materials have largely been overlooked so far, they can cause luminescence quenching and even complete luminescence excitation loss. Their direct observation and independent assignment in classical dopant (Eu) and hosts (CaF2, SrF2, BaF2) are very significant: They suggest that the occurrence of IVCT states in other lanthanide-activated materials is very likely overlooked and their impact is ignored.
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Affiliation(s)
- Jonas J Joos
- LumiLab, Department of Solid State Sciences, and Center for Nano- and Biophotonics (NB-Photonics) , Ghent University , 9000 Ghent , Belgium
| | - Luis Seijo
- Departamento de Química, Instituto Universitario de Ciencia de Materiales Nicolás Cabrera, and Condensed Matter Physics Center (IFIMAC) , Universidad Autónoma de Madrid , 28049 Madrid , Spain
| | - Zoila Barandiarán
- Departamento de Química, Instituto Universitario de Ciencia de Materiales Nicolás Cabrera, and Condensed Matter Physics Center (IFIMAC) , Universidad Autónoma de Madrid , 28049 Madrid , Spain
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12
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Stefanski M, Lukaszewicz M, Hreniak D, Strek W. Laser induced white emission generated by infrared excitation from Eu 3+:Sr 2CeO 4 nanocrystals. J Chem Phys 2018; 146:104705. [PMID: 28298121 DOI: 10.1063/1.4978237] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The laser induced white emission (LIWE) was observed from Eu3+:Sr2CeO4 nanocrystals. The samples were obtained in form of powders by the modified sol-gel route. The structure and morphology of the phosphors were investigated by powder X-ray diffraction and transmission electron microscope techniques. The intense LIWE occurred under reduced pressure and focused beam of near infrared laser excitation. The power and pressure dependencies exhibit evident threshold character typical for the avalanche effect. The photoconductivity of the Eu3+:Sr2CeO4 nanocrystals measured as a function of different powers of excitation source was analyzed.
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Affiliation(s)
- M Stefanski
- Institute of Low Temperature and Structure Research, Polish Academy of Sciences, 50-422 Wroclaw, Poland
| | - M Lukaszewicz
- Institute of Low Temperature and Structure Research, Polish Academy of Sciences, 50-422 Wroclaw, Poland
| | - D Hreniak
- Institute of Low Temperature and Structure Research, Polish Academy of Sciences, 50-422 Wroclaw, Poland
| | - W Strek
- Institute of Low Temperature and Structure Research, Polish Academy of Sciences, 50-422 Wroclaw, Poland
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13
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MacKeen C, Bridges F, Kozina M, Mehta A, Reid MF, Wells JPR, Barandiarán Z. Evidence That the Anomalous Emission from CaF 2:Yb 2+ Is Not Described by the Impurity Trapped Exciton Model. J Phys Chem Lett 2017; 8:3313-3316. [PMID: 28677980 DOI: 10.1021/acs.jpclett.7b01103] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Yb-substituted CaF2 exhibits an anomalous red-shifted luminescence after UV excitation, attributed to the relaxation of impurity trapped excitons (ITE). CaF2:Yb is the archetype system for this model, in which the Yb2+ ions can be excited into a long-lived (ms) exciton state. Upon de-excitation, the emission intensity should be proportional to the Yb2+ concentration, but that could not be checked when this model was first proposed. Using the X-ray absorption near edge structure (XANES) technique, we determine the fractions of Yb2+ and Yb3+ for low Yb concentrations, 0.01% to 0.1%, and thus determine the net concentration of Yb2+. A comparison with luminescence data shows that the intensity is not proportional to the Yb2+ concentration, and only a fraction of Yb2+ ions contributes to the anomalous luminescence. This is inconsistent with the ITE model and illustrates the importance of checking the dependence of the emission intensity on the Yb2+ concentration.
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Affiliation(s)
- C MacKeen
- Physics Department, University of California , Santa Cruz, California 95064, United States
| | - F Bridges
- Physics Department, University of California , Santa Cruz, California 95064, United States
| | - M Kozina
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - A Mehta
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - M F Reid
- Dodd-Walls Centre for Photonic and Quantum Technologies and Department of Physics and Astronomy, University of Canterbury , PB 4800, Christchurch 8140, New Zealand
| | - J-P R Wells
- Dodd-Walls Centre for Photonic and Quantum Technologies and Department of Physics and Astronomy, University of Canterbury , PB 4800, Christchurch 8140, New Zealand
| | - Z Barandiarán
- Departamento de Química, Instituto Universitario de Ciencia de Materiales Nicolás Cabrera, and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid , 28049 Madrid, Spain
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14
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Hughes-Currie RB, Ivanovskikh KV, Wells JPR, Reid MF, Gordon RA, Seijo L, Barandiarán Z. X-ray Excitation Triggers Ytterbium Anomalous Emission in CaF 2:Yb but Not in SrF 2:Yb. J Phys Chem Lett 2017; 8:1175-1178. [PMID: 28234013 DOI: 10.1021/acs.jpclett.7b00262] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Materials that luminesce after excitation with ionizing radiation are extensively applied in physics, medicine, security, and industry. Lanthanide dopants are known to trigger crystal scintillation through their fast d-f emissions; the same is true for other important applications as lasers or phosphors for lighting. However, this ability can be seriously compromised by unwanted anomalous emissions often found with the most common lanthanide activators. We report high-resolution X-ray-excited optical (IR to UV) luminescence spectra of CaF2:Yb and SrF2:Yb samples excited at 8949 eV and 80 K. Ionizing radiation excites the known anomalous emission of ytterbium in the CaF2 host but not in the SrF2 host. Wave function-based ab initio calculations of host-to-dopant electron transfer and Yb2+/Yb3+ intervalence charge transfer explain the difference. The model also explains the lack of anomalous emission in Yb-doped SrF2 excited by VUV radiation.
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Affiliation(s)
- Rosa B Hughes-Currie
- Department of Physics and Astronomy, University of Canterbury , PB 4800, Christchurch 8140, New Zealand
| | - Konstantin V Ivanovskikh
- Department of Physics and Astronomy, University of Canterbury , PB 4800, Christchurch 8140, New Zealand
- Institute of Physics and Technology, Ural Federal University , 620002 Ekaterinburg, Russia
| | - Jon-Paul R Wells
- Dodd-Walls Centre for Quantum and Photonic Technologies, Department of Physics and Astronomy, University of Canterbury , PB 4800, Christchurch 8140, New Zealand
| | - Michael F Reid
- Dodd-Walls Centre for Quantum and Photonic Technologies, Department of Physics and Astronomy, University of Canterbury , PB 4800, Christchurch 8140, New Zealand
| | - Robert A Gordon
- Moyie Institute and Deptartment of Physics, Simon Fraser University , Burnaby V5A 1S6, British Columbia, Canada
| | - Luis Seijo
- Departamento de Química, Instituto Universitario de Ciencia de Materiales Nicolás Cabrera, and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid , 28049 Madrid, Spain
| | - Zoila Barandiarán
- Departamento de Química, Instituto Universitario de Ciencia de Materiales Nicolás Cabrera, and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid , 28049 Madrid, Spain
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15
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Hughes-Currie RB, Ivanovskikh KV, Wells JPR, Reid MF, Gordon RA. The determination of dopant ion valence distributions in insulating crystals using XANES measurements. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2016; 28:135502. [PMID: 26941175 DOI: 10.1088/0953-8984/28/13/135502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Ytterbium-doped wide-bandgap fluoride crystals CaF2, SrF2 and NaMgF3 have been measured using x-ray absorption near edge structure (XANES) on the L3 edge to determine the ratio of trivalent to divalent Yb ions present in the crystals. This study improves upon previous XANES measurements of dopant ion valency by taking into account the x-ray emission transition probabilities for the divalent and trivalent species instead of simply assuming that the relative concentrations may be determined by the ratio of the x-ray excitation band areas. Trivalent to divalent ratios as high as 5 are inferred even at low total dopant ion concentrations of 0.05 mol% Yb.
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Affiliation(s)
- Rosa B Hughes-Currie
- Department of Physics and Astronomy, University of Canterbury, PB 4800, Christchurch 8140, New Zealand
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16
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Ab Initio Calculations on Excited States of Lanthanide Containing Materials. INCLUDING ACTINIDES 2016. [DOI: 10.1016/bs.hpcre.2016.03.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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17
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Suta M, Urland W, Daul C, Wickleder C. Photoluminescence properties of Yb2+ ions doped in the perovskites CsCaX3 and CsSrX3 (X = Cl, Br, and I) – a comparative study. Phys Chem Chem Phys 2016; 18:13196-208. [DOI: 10.1039/c6cp00085a] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photoluminescence spectra of Yb2+ ions doped into CsCaX3 and CsSrX3 (X = Cl, Br, and I) depict a manifold of transitions in high resolution, which allows a detailed understanding of the optical properties of divalent lanthanide ions in perovskite host lattices.
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Affiliation(s)
- Markus Suta
- Inorganic Chemistry
- Faculty of Science and Technology
- University of Siegen
- 57068 Siegen
- Germany
| | - Werner Urland
- Department of Chemistry
- University of Fribourg
- 1700 Fribourg
- Switzerland
| | - Claude Daul
- Department of Chemistry
- University of Fribourg
- 1700 Fribourg
- Switzerland
| | - Claudia Wickleder
- Inorganic Chemistry
- Faculty of Science and Technology
- University of Siegen
- 57068 Siegen
- Germany
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18
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Barandiarán Z, Seijo L. Metal-to-metal charge transfer between dopant and host ions: Photoconductivity of Yb-doped CaF2 and SrF2 crystals. J Chem Phys 2015; 143:144702. [PMID: 26472390 DOI: 10.1063/1.4932388] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Dopant-to-host electron transfer is calculated using ab initio wavefunction-based embedded cluster methods for Yb/Ca pairs in CaF2 and Yb/Sr pairs in SrF2 crystals to investigate the mechanism of photoconductivity. The results show that, in these crystals, dopant-to-host electron transfer is a two-photon process mediated by the 4f(N-1)5d excited states of Y b(2+): these are reached by the first photon excitation; then, they absorb the second photon, which provokes the Y b(2+) + Ca(2+) (Sr(2+)) → Y b(3+) + Ca(+) (Sr(+)) electron phototransfer. This mechanism applies to all the observed Y b(2+) 4f-5d absorption bands with the exception of the first one: Electron transfer cannot occur at the first band wavelengths in CaF2:Y b(2+) because the Y b(3+)-Ca(+) states are not reached by the two-photon absorption. In contrast, Yb-to-host electron transfer is possible in SrF2:Y b(2+) at the wavelengths of the first 4f-5d absorption band, but the mechanism is different from that described above: first, the two-photon excitation process occurs within the Y b(2+) active center, then, non-radiative Yb-to-Sr electron transfer can occur. All of these features allow to interpret consistently available photoconductivity experiments in these materials, including the modulation of the photoconductivity by the absorption spectrum, the differences in photoconductivity thresholds observed in both hosts, and the peculiar photosensitivity observed in the SrF2 host, associated with the lowest 4f-5d band.
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Affiliation(s)
- Zoila Barandiarán
- Departamento de Química, Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | - Luis Seijo
- Departamento de Química, Universidad Autónoma de Madrid, 28049 Madrid, Spain
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19
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Barandiarán Z, Meijerink A, Seijo L. Configuration coordinate energy level diagrams of intervalence and metal-to-metal charge transfer states of dopant pairs in solids. Phys Chem Chem Phys 2015; 17:19874-84. [DOI: 10.1039/c5cp02625c] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Configuration coordinate diagrams, which are normally used in a qualitative manner for the energy levels of active centers in phosphors, are quantitatively obtained here for intervalence charge transfer (IVCT) states of mixed valence pairs and metal-to-metal charge transfer (MMCT) states of heteronuclear pairs, in solid hosts.
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Affiliation(s)
- Zoila Barandiarán
- Departamento de Química
- Universidad Autónoma de Madrid
- 28049 Madrid
- Spain
- Instituto Universitario de Ciencia de Materiales Nicolás Cabrera
| | - Andries Meijerink
- Condensed Matter and Interfaces
- Debye Institute for Nanomaterials Science
- Utrecht University
- 3584 CC Utrecht
- The Netherlands
| | - Luis Seijo
- Departamento de Química
- Universidad Autónoma de Madrid
- 28049 Madrid
- Spain
- Instituto Universitario de Ciencia de Materiales Nicolás Cabrera
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