| 1. |
- Wang, W., et al.
(författare)
-
A new user-friendly materials science end station at the FinEstBeAMS beamline of MAX IV
- 2022
-
Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 2380
-
Konferensbidrag (refereegranskat)abstract
- FinEstBeAMS is an atmospheric and materials science beamline located at the 1.5 GeV storage ring of the MAX IV Laboratory in Lund, Sweden. It offers a very wide photon energy range 4.5-1300 eV and radiation with different polarization characteristics. The beamline has three end stations installed at two branch lines. The new solid state end station (SSES) is described in this paper. It is a high-throughput apparatus with flexible sample preparation options for X-ray photoemission, angle-resolved photoemission, and X-ray absorption spectroscopy. Three examples of experiments at room temperature demonstrate the capabilities of the SSES in the research field of surface science and condensed matter physics.
|
|
| 2. |
- Kaambre, T., et al.
(författare)
-
Resonant inelastic X-ray scattering at the Be 1s edge in BeO
- 2007
-
Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048. ; 156, s. 299-302
-
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.
|
|
| 3. |
- Kikas, A., et al.
(författare)
-
Resonant inelastic x-ray scattering and UV-VUV luminescence at the Be 1s edge in BeO
- 2010
-
Ingår i: Journal of Physics: Condensed Matter. - : IOP Publishing. - 1361-648X .- 0953-8984. ; 22:37
-
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.
|
|
| 4. |
|
|
| 5. |
- Kotlov, A, et al.
(författare)
-
Luminescence study of self-trapped holes in pure and Fe- or Mo-doped ZnWO4 crystals
- 2004
-
Ingår i: LUMDETR2003. - : Elsevier BV. ; 38, s. 715-715
-
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.
|
|
| 6. |
- Lushchik, A, et al.
(författare)
-
Control of excitonic and electron-hole processes in wide-gap crystals by means of elastic uniaxial stress
- 2002
-
Ingår i: Surface Review and Letters. - 0218-625X. ; 9:1, s. 299-304
-
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.
|
|
| 7. |
- Lushchik, A, et al.
(författare)
-
Creation of electronic excitations and defects by VUV radiation (6-40 eV) in wide-gap solids
- 2002
-
Ingår i: Radiation Effects and Defects in Solids. - : Informa UK Limited. - 1042-0150 .- 1029-4953. ; 157:6-12, s. 537-543
-
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.
|
|
| 8. |
- Lushchik, A, et al.
(författare)
-
Multiplication of electronic excitations and prospects for increasing scintillation efficiency in wide-gap crystals
- 2005
-
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
-
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.
|
|
| 9. |
- Lushchik, A, et al.
(författare)
-
Nano-scale radiation effects in wide-gap crystals under irradiation by VUV photons
- 2002
-
Ingår i: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - 0168-583X. ; 191:1-4, s. 135-143
-
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.
|
|
| 10. |
- Nagirnyi, V, et al.
(författare)
-
Emission decay kinetics in a CaWO4 : Bi crystal
- 2005
-
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. 61-65
-
Tidskriftsartikel (refereegranskat)abstract
- The decay kinetics of the 2.88 eV emission of pure and Bi-doped CaWO4 crystals has been studied in the temperature region of 4.2-300 K. The decay components connected with the radiative transitions from the triplet excited states of regular WO42- oxyanionic complexes and WO42- complexes perturbed by Bi3+ ions (WO42-(Bi3+) centres) have been identified. It is shown that WO4(Bi3+) centres can be excited directly above the edge of the fundamental absorption of CaWO4, or due to the energy transfer from the metastable state of a Bi3+ ion at the excitation in the Bi3+ absorption band at 4.4e.V. At temperatures T> 170 K, the excited state of the WO42-(Bi3+) centre is thermally ionised, giving rise to phosphorescence in the blue spectral region. These processes are compared with those known for excitons in PbWO4 crystals.
|
|
