| 1. |
- Omelkov, S. I., et al.
(författare)
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Recent advances in time-resolved luminescence spectroscopy at MAX IV and PETRA III storage rings
- 2022. - 1
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 2380
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Konferensbidrag (refereegranskat)abstract
- Short-wavelength synchrotron radiation excitation has been an indispensable tool in the studies of the properties of wide gap materials using time-resolved low-temperature luminescence spectroscopy. In recent years, several setups for such investigations have been launched at MAX IV Laboratory and Photon Science at DESY. Two permanently stationed time-resolved luminescence setups at FinEstBeAMS and P66 beamlines are in operation at MAX IV 1.5 GeV and Petra III storage rings, respectively. Mobile luminescence setups have been developed for studies at FemtoMAX and P23 beamlines. FinEstBeAMS, P66 and P23 provide time resolution from ?1/4160 to 100 ps. The FemtoMAX photon source based on an in-vacuum undulator getting an electron beam from the 3 GeV linear accelerator provides an exceptional time resolution of ?1/430 ps, limited by time response of the photodetector. The performance of the setups, achieved milestones and research challenges are discussed for four new luminescence stations available for the research community with the main focus on time-resolved techniques.
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| 2. |
- Kotlov, A., et al.
(författare)
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Excited states of molybdenum oxyanion in scheelite and wolframite structures
- 2007
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Ingår i: Radiation Measurements. - : Elsevier BV. - 1350-4487 .- 1879-0925. ; 42:4-5, s. 767-770
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Tidskriftsartikel (refereegranskat)abstract
- Scheelite CdMoO4 and wolframite eCdWO(4):MO (0.04-0.4wt%) single crystals were studied using the time-resolved spectroscopy under UV excitation over a temperature range of 1.85-300K. The threshold energies for the creation of free charge carriers were measured using the method of photostimulated luminescence. The decay kinetics of the main emission in CdMoO4 and the molybdenum-related emission in CdWO4:MO was studied and the parameters of the triplet excited states of molybdenum-related oxyanions were calculated. (C) 2007 Elsevier Ltd. All rights reserved.
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| 3. |
- Nagirnyi, V, et al.
(författare)
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Iron-related luminescence centers in ZnWO4 : Fe
- 2002
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Ingår i: Radiation Effects and Defects in Solids. - : Informa UK Limited. - 1042-0150 .- 1029-4953. ; 157, s. 1123-1123
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Tidskriftsartikel (refereegranskat)abstract
- A systematic spectroscopic study of single ZnWO4 :Fe crystals with different iron concentrations has been performed under excitation by ultraviolet light, by synchrotron radiation or under photostimulation by near-infrared light. The luminescence of Fe3+-related centres has been studied. It is shown that iron centres of different types efficiently promote the formation of crystal defects at low temperatures. Electrons and holes can be trapped near Fe2+ or Fe3+ ions, which is further revealed in phosphorescence, thermostimulated or photostimulated luminescence. At room temperature the main effect of iron impurity is to reduce the light yield of a ZnWO4 scintillator.
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| 4. |
- Feldbach, E., et al.
(författare)
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Low-temperature irradiation effects in lithium orthosilicates
- 2006
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 250, s. 159-163
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Konferensbidrag (refereegranskat)abstract
- The emission spectra of lithium orthosilicates (Li4SiO4) ceramics have been measured in the range of 1.8-5.8 eV under irradiation by 6-30 eV photons or 1-30 keV electrons at 6-300 K. The tunnel recombination phosphorescence, as well as luminescence, stimulated by 1.5-2.5 eV photons has been detected in the sample preliminarily irradiated at 6 or 80 K. The main peaks of thermally stimulated luminescence (TSL) in the irradiated ceramics have been observed at 72, 118 and 265 K. The creation spectra of the 118 K TSL peak, as well as the excitation spectrum of photostimulated luminescence (PSL) span the region of the intrinsic absorption of a lithium orthosilicate (9-30 eV). The intensity of PSL and the TSL peaks in Li4SiO4 ceramics prepared in hydrogen/argon atmosphere is several times lower than that in the mainly investigated Li4SiO4 ceramics prepared in the atmosphere of dry argon. The optical characteristics of Li4SiO4 are compared with the ones known for Li2O and SiO2. Low-temperature luminescent methods are promising for the investigation of electron-hole processes and radiation defects serving as the traps for tritium released in D-T fusion reactor blanket systems. (c) 2006 Elsevier B.V. All rights reserved.
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| 5. |
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| 6. |
- Kotlov, A, et al.
(författare)
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Luminescence study of self-trapped holes in pure and Fe- or Mo-doped ZnWO4 crystals
- 2004
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Ingår i: LUMDETR2003. - : Elsevier BV. ; 38, s. 715-715
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Konferensbidrag (refereegranskat)abstract
- Thermostimulated and photostimulated luminescence of ZnWO4, ZnWO4:Fe and ZnWO4:MO Crystals irradiated at low temperatures by X-rays or UV photons was studied in the temperature range 4.2-300 K in order to clarify the creation and recombination processes of the elementary colour centres. The connection of the luminescence phenomena with the self-trapped holes has been revealed. (C) 2003 Published by Elsevier Ltd.
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| 7. |
- Lushchik, A, et al.
(författare)
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Creation of electronic excitations and defects by VUV radiation (6-40 eV) in wide-gap solids
- 2002
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Ingår i: Radiation Effects and Defects in Solids. - : Informa UK Limited. - 1042-0150 .- 1029-4953. ; 157:6-12, s. 537-543
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Tidskriftsartikel (refereegranskat)abstract
- The processes of multiplication of electronic excitations (MEE), connected with the creation of secondary excitons or electron-hole (e-h) pairs by hot conduction electrons, are realized in wide-gap metal halides and oxides. In oxides, secondary e-h pairs can be also formed by 27-40 eV photons due to L 1 VV Auger transitions (with the participation of 2s oxygen holes). The excitation spectra of luminescence and the creation spectra of electron F centres or hole V centres have been measured for Na 6 Al 6 Si 6 O 24 (NaI) 2x sodalites and MgO:Be, respectively, at 8-80 K. A high local density of excitations has been revealed under MEE conditions in KBr and Br sodalites with self-trapping excitons and holes.
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| 8. |
- Lushchik, A, et al.
(författare)
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Multiplication of electronic excitations and prospects for increasing scintillation efficiency in wide-gap crystals
- 2005
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier BV. - 0167-5087 .- 0168-9002. ; 537:1-2, s. 45-49
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Tidskriftsartikel (refereegranskat)abstract
- A comparative analysis of the electron-hole (e-h) excitation mechanism of impurity luminescence has been performed for wide-gap oxides (WGO) and alkali halides crystals (AHC). A low quantum yield of scintillation in WGO with respect to that in AHC is connected with the high value of the average energy needed for the creation of an e-h pair in WGO. In AHC and many WGO, the width of a valence band E, is smaller than the energy gap E, and hot valence holes are not able to create any secondary e-h pairs. The E-v/E-g ratio that describes ''hole losses'' in scintillators is 1.5-2.0 times higher in WGO than in CsI. The scenario of the two-step transformation of an e-h pair or an anion exciton into two emitted photons in alpha-Al2O3:Mg2+, Ti4+ has been considered.
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| 9. |
- Lushchik, A, et al.
(författare)
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Nano-scale radiation effects in wide-gap crystals under irradiation by VUV photons
- 2002
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - 0168-583X. ; 191:1-4, s. 135-143
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Tidskriftsartikel (refereegranskat)abstract
- The creation spectra of F centres by synchrotron radiation of 5-35 eV have been measured for Na6Al6Si6O24(NaI)(2x) and Na6Al6Si6O24(NaBr)(2x) optical ceramics at 8 and 80 K. The exciting photons cause the excitation and ionization of halogen ions (6-8 eV) and of an aluminosilicate carcass (8.5-31 eV) or the excitation of Na+ ions (32-35 eV). An exciting photon of 20-26 and 27-31 eV creates two or three electron-hole pairs, respectively. Besides the electron-hole creation mechanism of F centres with the participation of pre-irradiation defects, the basic interstitial-vacancy creation mechanism of Frenkel defect pairs is realized in socialites at high doses of irradiation at 300 K. A Br-0 atom formed at the irradiation in a regular beta-cage can penetrate into a neighbouring cage. As a result, an F centre and a Br-2(-) molecule (H centre) are formed and the interdefect distance in this pair is about I nm. The efficiency of F-H pair creation is especially high under the conditions of multiplication of electron-hole pairs. In contrast to alkali halides the crowdion configuration of interstitials does not exist in sodalites and F-H pairs are stable up to 450 K.
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| 10. |
- Nagirnyi, V, et al.
(författare)
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Conduction band structure in oxyanionic crystals
- 2005
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Ingår i: SCINT2005, 8thInternational Conference on Inorganic Scintillators and their use in Scinetific and Industrial Applications.
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Konferensbidrag (refereegranskat)
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