| 1. |
- Beideck, DJ, et al.
(författare)
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Lifetimes of 5d96p and 5d86s6p levels in Hg iii
- 1993
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 47:2, s. 884-889
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Tidskriftsartikel (refereegranskat)abstract
- Experimental and theoretical studies of lifetimes and transition probabilities for doubly ionized mercury, Hg III, are reported. Such data are currently of great astrophysical interest because observations with the Goddard high resolution spectrograph on board the Hubble space telescope have shown some 5d(9)6s-5d(9)6p transitions of Hg III in the spectrum of the chemically peculiar star chi Lupi. We now report experimental lifetimes for some selected 5d(9)6p and 5d(8)6s6p levels, determined by beam-foil spectroscopy, and compare the results with theoretical transition probabilities based on relativistic multiconfiguration Dirac-Fock calculations.
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| 2. |
- Bogdanovich, P, et al.
(författare)
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Ab initio wavelengths and oscillator strengths for Cl X
- 2003
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Ingår i: Physica Scripta. - 0031-8949. ; 67:1, s. 44-51
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Tidskriftsartikel (refereegranskat)abstract
- Using the configuration interaction technique, the energy spectra of 2s(2)2p(4), 2s2p(5), 2s(2)2p(3)3s, 2s(2)2p(3)3d, configurations of oxygen-like chlorine Cl X have been calculated. The obtained data are used for the evaluation of wavelengths and oscillator strengths of all possible one-electron and two-electron 2s(2)2P(3)3p-2s2p(5) electric dipole transitions. The calculated results are compared with recent experimental data.
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| 3. |
- Bogdanovich, P, et al.
(författare)
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Theoretical lifetimes for all states of five Cl X configurations
- 2003
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - 0168-583X. ; 205, s. 70-73
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Tidskriftsartikel (refereegranskat)abstract
- Ab initio calculations including relativistic and correlation corrections were performed to obtain energy spectra and lifetimes for all states of first five configurations of Cl X.
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| 4. |
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| 5. |
- 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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| 6. |
- Henderson, M, et al.
(författare)
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Lifetimes of the 5d(9)6p levels in HgIII
- 1999
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 59:5, s. 4068-4070
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Tidskriftsartikel (refereegranskat)abstract
- We report measurements and theoretical calculations for the lifetimes of the 5d(9)6p levels in Hg nr with J = 0,2,3,4. This is an extension of earlier measurements of the lifetimes of the 5d(9)6p levels in Hg III with J = 1, and now provides data for all 12 of the levels. The results also provide an isoelectronic comparison with earlier studies of these levels in Au II of the Pt sequence, and a homologous comparison with earlier studies of the 4d(9)5p levels in Ag II, Cd III, and In IV in the Pd sequence. [S1050-2947(99)10905-3].
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| 7. |
- Hutton, Roger, et al.
(författare)
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Some historic and current aspects of plasma diagnostics using atomic spectroscopy
- 2010
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Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 43:14
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we give a short introduction to the use of atomic spectroscopy in plasma diagnostics. Both older works and exciting new branches of atomic physics, which have relevance to diagnostics, are discussed. In particular we focus on forbidden lines in Be-like ions, lines sensitive to magnetic fields and levels which have a lifetime dependence on the nuclear spin of the ion, i.e. f-dependent lifetimes. Finally we mention a few examples of where tokamaks, instead of needing atomic data, actually provide new data and lead to developments in atomic structure studies.
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| 8. |
- Jupén, Christer, et al.
(författare)
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Additions to the spectra of highly ionized molybdenum, Mo XXIV-Mo XXVIII
- 2003
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Ingår i: Physica Scripta. - 0031-8949. ; 68:4, s. 230-232
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Tidskriftsartikel (refereegranskat)abstract
- We have observed radiation from highly charged molybdenum ions in the JET tokamak plasmas. Spectra were recorded in the wavelength range 70-110 Angstrom, resulting in the classification of 15 new n = 3. Deltan = 0 transitions in Mo XXIV-Mo XXVIII.
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| 9. |
- Kaambre, T., et al.
(författare)
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Resonant inelastic X-ray scattering at the Be 1s edge in BeO
- 2007
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048. ; 156, s. 299-302
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Tidskriftsartikel (refereegranskat)abstract
- We present the resonant inelastic X-ray scattering (RIXS) spectra of BeO at the Be 1s photoabsorption edge. The RIXS spectra excited in the vicinity of the core exciton resonance show two principal features: the scattering on a valence exciton (which at higher excitation energies verges into the characteristic K alpha emission), and a remarkably strong energy loss side-band to the elastic scattering peak, which has a maximum width of 6 eV and has intensity, at resonance, comparable to the valence scattering. The energy loss side-band appears to result from rapid lattice relaxation at the absorption site on the X-ray scattering time-span. (c) 2006 Elsevier B.V. All rights reserved.
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| 10. |
- Kikas, A., et al.
(författare)
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Effect of phase composition on X-ray absorption spectra of ZrO2 thin films
- 2007
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048. ; 156, s. 303-306
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Tidskriftsartikel (refereegranskat)abstract
- The X-ray photoabsorption spectra of ZrO2 films with different phase compositions were measured. The analysis of the results obtained shows that due to the site-sensitivity the X-ray photoabsorption spectroscopy is an attractive method for characterization of the ZrO2 structure. This allows application of the X-ray spectroscopy in investigation of the crystal structure in the various stages of the thin film growth including the initial stage of the ZrO2 growth. (c) 2006 Elsevier B.V. All rights reserved.
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| 11. |
- Kikas, A, et al.
(författare)
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NaK photoabsorption and resonant KLL Auger spectra in naf and NaCl
- 2002
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Ingår i: Surface Review and Letters. - 0218-625X. ; 9:2, s. 1303-1308
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Tidskriftsartikel (refereegranskat)abstract
- The nature of Na Is photoabsorption in NaF and NaCl is investigated using the resonant Auger decay of Na Is core excitations. The appearance of new peaks in Auger spectra, when the energy of excitation coincides with the photoabsorption thresholds, shows that the core excitons are created in the threshold region of the Na 1s photoabsorption spectrum. The core excitons around 1074.2 eV originate from the dipole-forbidden 1s(-1)3s final state, the population of which is made possible by the symmetry disruption at the photoabsorption site. Another core exciton, excited at photon energies of 1076.8 eV in NaF and 1076.3 eV in NaCl, originates from 1s(-1)3p states similar to atoms of Ne and Na. Resonant Auger spectra show also that in NaCl the first sharp photoabsorption maximum at 1076.6 eV has only partially excitonic character.
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| 12. |
- Kikas, A., et al.
(författare)
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Resonant inelastic x-ray scattering and UV-VUV luminescence at the Be 1s edge in BeO
- 2010
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Ingår i: Journal of Physics: Condensed Matter. - : IOP Publishing. - 1361-648X .- 0953-8984. ; 22:37
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Tidskriftsartikel (refereegranskat)abstract
- We carried out a combined study of UV-VUV luminescence and resonant x-ray emission from BeO single crystals with incident photon energies in the vicinity of the Be 1s absorption edge. The x-ray emission spectra show that at the Be 1s photoabsorption edge the lattice relaxation processes in the excitation site take place already on the timescale of the radiative decay of the core excitation. Comparison of the x-ray emission and the luminescence spectra indicates that the maximum energy loss of the process of lattice relaxation during the decay of inner-shell holes is similar to the loss that occurs in the self-trapping process of valence excitons. The possible decay channels of core excitations have been discussed and the mechanism for the creation of 5.2 eV luminescence at the photoabsorption resonances has been suggested.
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| 13. |
- Kikas, A., et al.
(författare)
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Resonant inelastic x-ray scattering at the F 1s photoabsorption edge in LiF : Interplay of excitonic and conduction states, and Stokes' doubling
- 2004
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : American Physical Society. - 1098-0121 .- 1550-235X. ; 70:8
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Tidskriftsartikel (refereegranskat)abstract
- The excitation-decay processes at the F 1s photoabsorption edge in LiF crystal are studied using resonant inelastic x-ray scattering spectroscopy. The Raman-type linear dispersion and the narrowing of the x-ray fluorescence peak are observed at resonant excitation. A theoretical model based on the Kramers-Heisenberg formula describes well the main features in fluorescence spectra and allows one to separate the contributions of the exciton and the conduction states in the scattering spectra. At the same time, the role of the shape of the spectral distribution within the incident radiation is emphasized as being critically sensitive to the number, kind, and onset of the spectral features which finally appear in the scattering spectra at a particular incident photon energy, particularly in the subthreshold excitation region.
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| 14. |
- Kikas, A, et al.
(författare)
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Resonant inelastic X-ray scattering at the K edge of oxygen and fluorine in insulators
- 2005
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048. ; 144-147, s. 845-848
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Tidskriftsartikel (refereegranskat)abstract
- Here we present the results of a study of the electronic structure using the resonant inelastic scattering process at the F 1s photoabsorption edge in LiF and O 1s edge of MgO crystals. In case of excitations in the sub-threshold region, the Raman-type linear dispersion of X-ray fluorescence peak was observed for the studied compounds. In LiF, the narrowing of the X-ray fluorescence peak is observed at pre-threshold excitation, which can be related to the creation of a core exciton, but no core excitons were identified in MgO.
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| 15. |
- Kisand, V, et al.
(författare)
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VUV spectroscopy of pure and Sm2+ doped SrFCl crystals
- 2003
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Ingår i: Physica Status Solidi. B: Basic Research. - : Wiley. - 0370-1972. ; 239:1, s. 246-250
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Tidskriftsartikel (refereegranskat)abstract
- The creation and relaxation of electronic excitations in pure crystalline SrFCl and Sm2+ doped SrFCl were investigated using vacuum ultraviolet (VUV) spectroscopic methods. In the emission spectra of pure SrFCl and SrFCl: Sm2+ a strong emission band in the vicinity of 4.7 eV was detected, connected to self-trapped exciton (STE) having a Cl-2(-) core. The threshold for creation of STE was detected at 8.5 eV in the excitation spectrum of pure SrFCl and at 7.6 eV for Sm2+ doped SrFCI. It was demonstrated that the excitation spectrum of Sm2+ emission is determined with direct excitation of a Sm2+ center below 7.6 eV and with excitation of the SrFCl host above 7.6 eV. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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| 16. |
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| 17. |
- Kramida, A. E., et al.
(författare)
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Additions to the spectrum and energy levels and a critical compilation of helium-like and hydrogen-like boron, BIV and BV
- 2008
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Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 78:2
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Tidskriftsartikel (refereegranskat)abstract
- Using beam-foil spectroscopy, we have observed several new lines in the B IV and B V spectra. This experimental work was combined with theoretical calculations using ab initio and semi-empirical techniques. We have also critically evaluated all previous and recent experimental and theoretical data for these spectra. Complete data on wavelengths and energy levels based on this analysis are tabulated.
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| 18. |
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| 19. |
- Kramida, A. E., et al.
(författare)
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Additions to the spectrum and energy levels and critical compilation of doubly ionized boron, BIII
- 2008
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Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 78:2
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Tidskriftsartikel (refereegranskat)abstract
- We have undertaken the study of the Li-like spectrum of doubly ionized boron, B III. The spectroscopic data have been obtained with beam-foil spectroscopy and high-resolution spark spectroscopy. The experimental work was combined with theoretical calculations using ab initio and semi-empirical techniques. About 50 new transitions have been observed, and most of the previously known lines have been measured with improved accuracy. We have also critically evaluated all previous and recent data for this spectrum. Complete data on wavelengths and energy levels based on this analysis are tabulated.
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| 20. |
- Lushchik, A, et al.
(författare)
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Control of excitonic and electron-hole processes in wide-gap crystals by means of elastic uniaxial stress
- 2002
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Ingår i: Surface Review and Letters. - 0218-625X. ; 9:1, s. 299-304
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Tidskriftsartikel (refereegranskat)abstract
- The time-resolved emission spectra and the excitation spectra of the main emissions have been measured for the first time in stressed and unstressed RbI crystals using synchrotron radiation of 10-30 eV at 8 K. It has been shown that the applied elastic uniaxial stress (EUS) offers promise for the separation of the elementary multiplication mechanisms of electronic excitations. A different influence of EUS on the self-trapping of excitons or holes at 8 K has been discussed. The mean free path of free excitons decreases, while that of valence holes increases in a stressed RbI crystal.
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| 21. |
- 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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| 22. |
- 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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| 23. |
- 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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| 24. |
- Mannervik, S, et al.
(författare)
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1s2s2p2 5p3 5S transition in B ii
- 1987
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 35:7, s. 3136-3138
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Tidskriftsartikel (refereegranskat)
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| 25. |
- Martinson, Indrek
(författare)
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Atomfysik med accelererade joner
- 1977
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Ingår i: Kosmos. - 0368-6213. ; 54, s. 151-169
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Tidskriftsartikel (populärvet., debatt m.m.)
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