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519 results on '"Zazubovich, S."'

153. An effect of Zr4+ co-doping of YAP:Ce scintillator

Author

Nikl, M, primary, Mares, J.A, additional, Chval, J, additional, Mihokova, E, additional, Solovieva, N, additional, Martini, M, additional, Vedda, A, additional, Blazek, K, additional, Maly, P, additional, Nejezchleb, K, additional, Fabeni, P, additional, Pazzi, G.P, additional, Babin, V, additional, Kalder, K, additional, Krasnikov, A, additional, Zazubovich, S, additional, and D’Ambrosio, C, additional

Published
2002
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156. Effect of magnetic field on the decay kinetics of triplet luminescence of the self-trapped exciton perturbed by Tl+ ion in thallium-doped cesium halides.

Author

Nagirnyi, V., Stolovich, A., Zazubovich, S., Zepelin, Viktor, Pazzi, G. P., Nagirnyi, V., Stolovich, A., Zazubovich, S., Zepelin, Viktor, and Pazzi, G. P.

Abstract

Decay kinetics of visible emission of thallium centre in CsCl:Tl, CsBr:Tl and CsI:TI crystals is studied in the magnetic field B // [001] at 0.35-0.45 K. Our previous interpretation of this emission as the triplet luminescence of the self-trapped exciton perturbed by Tl+ ion is confirmed. However, the detailed structure of the corresponding relaxed excited state is found to be much more complicated than that concluded before.

Published
1996

157. RES structure of Bi3+ centres in KCl:Bi,S and CaO:Bi crystals.

Author

Aceves, R., Flores, M. B., Maaroos, A., Nagirnyi, V., Salas, R. P., Tsuboi, T., Zazubovich, S., Zepelin, Viktor, Aceves, R., Flores, M. B., Maaroos, A., Nagirnyi, V., Salas, R. P., Tsuboi, T., Zazubovich, S., and Zepelin, Viktor

Abstract

Emission, excitation, and polarization spectra as well as decay kinetics are studied at 4.2 to 500 K for the luminescence of Bi3+ centres in two crystals (KCl and CaO) with strongly different electron-phonon interaction. It is concluded that three bands at approximate to 2.5, 3.11, and approximate to 1.5 eV, observed in the emission spectrum of the kCl:Bi, S crystal belong to the same centre, but arise from states of different origin; The splitting of the 2.5 eV band, caused by the presence of a defect (S2-) near a Bi3+ ion is detected. Besides the well-known tripler 3.3 and 3.1 eV bands, a new 4.15 eV emission is found in CaO:Bi crystal: which is ascribed to transitions from the singlet excited state of the Bi3+ ion. The structure and the parameters of the relaxed excited states are determined and the models of the corresponding Bi3+ centres are discussed.

Published
1996

158. Relaxed excited state structure and luminescence of thallium-doped caesium chloride and bromide.

Author

Mihokova, E., Nagirnyi, V., Nikl, M., Stolovich, A., Pazzi, G. P., Zazubovich, S., Zepelin, V., Mihokova, E., Nagirnyi, V., Nikl, M., Stolovich, A., Pazzi, G. P., Zazubovich, S., and Zepelin, V.

Abstract

Four bands, all belonging to the main thallium centres, have been detected in the emission spectra of CsCl:Tl and CsBr:Tl crystals. Their spectral, polarization and kinetic characteristics have been studied from 0.45 up to 360 K. It has been shown that the new model proposed by us recently for the relaxed excited state (RES) structure of the luminescence centre in CsI:Tl crystals is valid for CsCl:Tl and CsBr:Tl crystals as well. Two ultraviolet emission bands excited mainly in the A absorption band of Tl+ centres are ascribed to electronic transitions from trigonal and tetragonal Jahn-Teller minima of the tripler RES of Tl+. Two visible bands excitable mainly in the higher energy absorption bands of CsCl:Tl and CsBr:Tl are connected with two different off-centre configurations of self-trapped exciton perturbed by the Tl+ ion. The parameters of the corresponding excited state minima have been calculated. The mixing of the impurity and halogen excited states has been shown to decrease markedly in the sequence of anions I- --> Br- --> Cl-.

Published
1996

163. Spectroscopy of CsPbBr3 quantum dots in CsBr:Pb crystals

Author

Aceves, R., primary, Babin, V., additional, Flores, M.Barboza, additional, Fabeni, P., additional, Maaroos, A., additional, Nikl, M., additional, Nitsch, K., additional, Pazzi, G.P., additional, Salas, R.Perez, additional, Sildos, I., additional, Zazubovich, N., additional, and Zazubovich, S., additional

Published
2001
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166. Peculiarities of the triplet relaxed excited state structure in thallium-doped cesium halide crystals.

Author

Nagirnyi, V., Stolovich, A., Zazubovich, S., Zepelin, Viktor, Nikl, M., Mihokova, E., Pazzi, G. P., Nagirnyi, V., Stolovich, A., Zazubovich, S., Zepelin, Viktor, Nikl, M., Mihokova, E., and Pazzi, G. P.

Abstract

Four bands, all belonging to the main thallium centre, are detected in the tripler luminescence spectrum of thallium-doped cesium halides under excitation in impurity absorption bands. Their spectral, polarization and kinetics characteristics are studied at 0.35 to 360 K. The parameters of the corresponding relaxed excited states (RES) minima are calculated. Two ultraviolet emission bands are ascribed to electronic transitions from trigonal and tetragonal Jahn-Teller minima of the triplet RES of Tl+ ion. Two visible bands are assumed to arise from two different off-centre configurations of a self-trapped exciton perturbed by Tl+ ion.

Published
1995

167. Peculiarities of the triplet relaxed excited-state structure and luminescence of a CsI:Tl crystal

Author

Nagirnyi, V., Stolovich, A., Zazubovich, S., Zepelin, Viktor, Mihokova, E., Nikl, M., Pazzi, G. P., Salvini, L., Nagirnyi, V., Stolovich, A., Zazubovich, S., Zepelin, Viktor, Mihokova, E., Nikl, M., Pazzi, G. P., and Salvini, L.

Abstract

Four emission bands, all belonging to the main thallium centres, have been detected in CsI:Tl, and their spectral, polarization and kinetic characteristics have been studied at 0.35-320 K. A new model is proposed for the excited states responsible for the luminescence of thallium-doped caesium iodide. In this model, the main thallium centre is considered as a cluster consisting of a Tl+ ion and at least 12 I- and 11 Cs+ ions. Two weak ultraviolet emission bands of CsI:TI (3,31 and 3.09 eV) are ascribed to electronic transitions from trigonal and tetragonal Jahn-Teller minima of the tripler relaxed excited state, whose structure is similar to that of Tl+ centres in Fee alkali halides. Two intense visible bands (2.55 and 2.25 eV) are assumed to arise from two different ('weak' and 'strong') off-centre configurations of a self-trapped exciton perturbed by the Tl+ ion. The minima responsible for all the emission bands are located on the same adiabatic potential energy surface. The excitonic-like nature of visible emission could explain the high scintillation efficiency of CsI:Tl.

Published
1995

170. A new model for the visible emission of the CsI: Tl crystal.

Author

Nagirnyi, V., Zazubovich, S., Zepelin, Viktor, Nikl, M., Pazzi, G. P., Nagirnyi, V., Zazubovich, S., Zepelin, Viktor, Nikl, M., and Pazzi, G. P.

Abstract

Four emission bands, all belonging to the main thallium centre, are detected in a CsI:Tl crystal and their spectral, polarization and kinetic characteristics are studied at 1.7 to 320 K. Two weak ultraviolet bands (3.31 and 3.09 eV) are ascribed to electronic transitions from trigonal and tetragonal Jahn-Teller minima of the triplet relaxed excited state of Tl+. Two intense visible bands (2.55 and 2.25 eV) are assumed to arise from two different off-centre configurations of a self-trapped exciton perturbed by the Tl+ ion.

Published
1994

171. Origin of slow low-temperature luminescence in undoped and Ce-doped Y2SiO5 and Lu2SiO5 single crystals.

Author

Jary, V., Krasnikov, A., Nikl, M., and Zazubovich, S.

Subjects
LUMINESCENCE, DYNAMICS, CRYSTALS, ELECTRONIC excitation, MATHEMATICS
Abstract

At 4.2-300 K, the steady-state and time-resolved emission and excitation spectra as well as the luminescence decay kinetics in the 10 μs-10 s time range are studied for the undoped and Ce3+-doped single crystals of Y2SiO5 and Lu2SiO5. At low temperatures, a broad intrinsic emission band located at 2.55 eV in Y2SiO5 and 2.58 eV in Lu2SiO5 is observed in the luminescence spectra of all the crystals studied under excitation in the charge-transfer absorption region (with Eexc > 4.2 eV). This emission reveals the slow non-exponential decay kinetics characteristic for tunneling recombination processes. In the slow decay kinetics of the low-temperature luminescence of Ce3+-doped crystals, both the multi-exponential and the non-exponential decay stages are detected. The origin of the defects, responsible for the undesirable slow low-temperature luminescence of the undoped and Ce3+-doped Y2SiO5 and Lu2SiO5 crystals is considered. A new mechanism of the processes, resulting in the appearance of different luminescence decay stages, is proposed. [ABSTRACT FROM AUTHOR]

Published
2015
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172. Electron and hole traps in X-ray irradiated Y2 Si O5 and Lu2 Si O5 crystals.

Author

Kärner, T., Laguta, V., Nikl, M., and Zazubovich, S.

Subjects
ELECTRONS, X-rays, LUMINESCENCE, SOLUTION (Chemistry), LIGHT sources
Abstract

Characteristics of thermally stimulated luminescence (TSL) are studied for the X-ray irradiated at 4, 80, or 295 K nominally undoped Y2SiO5 and Lu2SiO5 single crystals of different origin, containing traps for holes (Ce3+, Tb3+ ions) and electrons (Eu3+, Mo6+ ions), as well as for the Sm3+-doped Lu2SiO5 crystal. For the first time, the TSL glow curves of these materials are measured separately for the electron (Ce3+-, Tb3+-related) and hole (Sm3+-, Eu3+-related) recombination luminescence. Owing to that, the TSL peaks, arising from thermal destruction of electron centers and hole centers, are separately identified. For some TSL peaks, thermal stability parameters of the corresponding traps are calculated. The results are compared with those obtained for Ce3+-doped Y2SiO5 and Lu2SiO5 crystals. [ABSTRACT FROM AUTHOR]

Published
2014
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184. Quantum size effect in the excitonic luminescence of CsPbX3-like quantum dots in CsX (X = Cl, Br) single crystal host

Author

Nikl, M., primary, Nitsch, K., additional, Polák, K., additional, Mihókova, E., additional, Zazubovich, S., additional, Pazzi, G.P., additional, Fabeni, P., additional, Salvini, L., additional, Aceves, R., additional, Barbosa-Flores, M., additional, Salas, R.Perez, additional, Gurioli, M., additional, and Scacco, A., additional

Published
1997
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197. Energy migration and Gd3+↔ Ce3+ transfer in Ce3+-doped GdP3O9 metaphosphate.

Author

Demchenko, P., Gektin, A., Krasnikov, A., Pashuk, I., Shalapska, T., Stryganyuk, G., Voloshinovskii, A., and Zazubovich, S.

Subjects
ENERGY transfer, LUMINESCENCE spectroscopy, LUMINESCENCE measurement, EXCITED state energies, DOPING agents (Chemistry), IONIC crystals in gadolinium, CESIUM ions
Abstract

Luminescence-kinetics studies of Ce3+-doped GdP3O9 metaphosphate, which was prepared by a melt-solution technique, are performed using time-resolved luminescence spectroscopy techniques at T = 4.2-300 K. The processes of energy migration along the Gd3+ sub-lattice and energy transfer between Gd3+ and Ce3+ ions are investigated. At low temperatures, the emission of Gd3+ is caused by the radiative decay of its lowest-energy relaxed excited 6P7/2 state, and the Gd3+ ? Ce3+ energy transfer is absent. As the temperature increases, the thermally stimulated population of the higher energy 6P5/2, 6P3/2 levels of the Gd3+ 6PJ-excited state takes place, which reveals itself in a higher energy shift of the Gd3+ 6PJ ? 8S7/2 emission band. The phonon-assisted population of the Gd3+ 6P5/2 excited level at T <150K is suggested to be responsible for the increase in probability of energy migration along the Gd3+ sub-lattice followed by the Gd3+ ? Ce3+ energy transfer. The more effective Gd3+ ? Ce3+ energy transfer at T >150K takes place owing to the thermally stimulated population of the highest-energy 6P3/2 excited level together with the lower energy shift of the Ce3+ 4f-5d1 absorption band. Unlike the Gd3+ ? Ce3+ transfer, the reverse Ce3+ ? Gd3+ energy transfer is observed at any temperature. [ABSTRACT FROM AUTHOR]

Published
2013
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