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1.
The paper presents experimental results on recombination processes in lanthanum beryllate (BLO) single crystals (undoped BLO, and doped with 0.5 at % by Ce3+ and Pr3+ ions) obtained using XRL-spectroscopy at T = 8, 80 and 290 K and thermoluminescence technique in the temperature range of 8–650 K. The paper discusses spectra of the steady-state XRL-luminescence recorded in the energy range from 1.5 to 6.2 eV at different temperatures between 8 and 290 K; temperature dependences of XRL intensity recorded in the temperature range from 8 to 650 K; thermoluminescence glow curves recorded in spectral-integrated regime after X-ray exposure at T0 = 8 or 290 K. 相似文献
2.
L. Marciniak D. Hreniak A. Dobrowolska E. Zych 《Applied Physics A: Materials Science & Processing》2010,99(4):871-877
Powders and thin films of nanocrystalline yttrium disilicate (Y2Si2O7) doped with Ce3+ have been prepared by a sol–gel method. Structure and morphology of the synthesised samples have been determined and spectroscopic
properties compared. The triclinic α-Y2Si2O7 form (space group P 1-) for the powders annealed between 1000°C and 1200°C has been found. A total conversion into a thortveitite-type
monoclinic β-Y2Si2O7 polymorph after annealing of powder samples at 1400°C (space group C2/m) has been observed. In the case of films even at
1300°C the basically pure triclinic α-Y2Si2O7 phase was observed with luminescent spectroscopy. The influence of grain size, controlled by thermal treatment, on the structure
and luminescence properties of the fabricated materials are presented and discussed. 相似文献
3.
A.N. Yunusova M.A. Marisov V.V. Semashko L.A. Nurtdinova S.L. Korableva 《Optics Communications》2012,285(18):3832-3836
Photochemical properties of Ce3+:SrAlF5 and Ce3+,Yb3+:SrAlF5 single crystals together with spectroscopic and kinetic characteristics of several optically nonequivalent impurity centers and energy transfer between them are described. It is shown that co-activation by Yb3+ ions effectively suppresses color centers in Ce,Yb:SAF crystals. It was found out that in Ce,Yb:SAF crystals Yb ions exist simultaneously in 2+ and 3+ valent state. Three types of optically nonequivalent luminescent centers corresponding to the doublets in luminescence spectrum centered at 290, 305 and 370 nm (CeI, CeII, CeIII, respectively) have been observed. Analysis of luminescence spectra and decays leads to the conclusion that there is no energy transfer between either cerium centers or from Ce3+ to Yb2+ apart from the CeIII center which luminescence is slightly quenched by Yb2+. 相似文献
4.
V. A. Pustovarov I. N. Ogorodnikov S. I. Omelkov S. O. Cholakh L. I. Isaenko 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2010,4(4):666-670
The results of a study of time-resolved photoluminescence (PL) and energy transfer in both pure and doped with Ce3+ ions SrAlF5 (SAF) single crystals are presented. The time-resolved and steady-state PL spectra in the energy range of 1.5–6.0 eV, the
PL excitation spectra and the reflectivity in the energy range of 3.7–21 eV, as well as the PL decay kinetics were measured
at 8.8 and 295 K. The lattice defects were revealed in the low temperature PL spectra (emission bands at 2.9 and 4.5 eV) in
the undoped SAF crystals. The luminescence spectra of the doped Ce3+:SAF crystals demonstrate a new selective emission bands in the range of 3.7–4.5 eV with the exponential decay kinetics (τ
≈ 60 ns at X-ray excitation). These bands correspond to the d-f transitions in Ce3+ ions, which occupy nonequivalent sites in the crystal lattice. 相似文献
5.
D. T. Valiev E. F. Polisadova K. N. Belikov N. L. Egorova 《Optics and Spectroscopy》2014,116(5):677-682
The luminescent characteristics of Li2O-B2O3-P2O5-CaF2 (LBPC) glasses doped with Gd3+ and Tb3+ ions and codoped with Ce3+ are studied by pulsed optical spectrometry under electron beam excitation. It is found that in glass with Ce3+ and Gd3+ ions a decrease in the decay time of gadolinium luminescence in the 312-nm band (6 P J → 8 S 7/2) was observed. It is shown that in the glass LBPC: Tb, Ce, an increase in the emission intensity in the main radiative transitions in terbium ion was observed. In the kinetics of luminescence band 545 nm of LBPC: Tb, Ce glasses, is present stage of buildup, the character of which changes with the doped of Ce3+ ions. The mechanism of energy transfer in LBP glasses doped with rare elements is discussed. 相似文献
6.
V. A. Pustovarov I. N. Ogorodnikov S. I. Omelkov L. I. Isaenko A. P. Yelisseyev A. A. Goloshumova S. I. Lobanov P. G. Krinitsyn 《Physics of the Solid State》2014,56(3):456-467
The electronic and crystal structures of SrMgF4 single crystals grown by the Bridgman method have been investigated. The undoped SrMgF4 single crystals have been studied using low-temperature (T = 10 K) time-resolved fluorescence optical and vacuum ultraviolet spectroscopy under selective excitation by synchrotron radiation (3.7–36.0 eV). Based on the measured reflectivity spectra and calculated spectra of the optical constants, the following parameters of the electronic structure have been determined for the first time: the minimum energy of interband transitions E g = 12.55 eV, the position of the first exciton peak E n = 1 = 11.37 eV, the position of the maximum of the “exciton” luminescence excitation band at 10.7 eV, and the position of the fundamental absorption edge at 10.3 eV. It has been found that photoluminescence excitation occurs predominantly in the region of the low-energy fundamental absorption edge of the crystal and that, at energies above E g , the energy transfer from the matrix to luminescence centers is inefficient. The exciton migration is the main excitation channel of photoluminescence bands at 2.6–3.3 and 3.3–4.2 eV. The direct photoexcitation is characteristic of photoluminescence from defects at 1.8–2.6 and 4.2–5.5 eV. 相似文献
7.
<正>We report the luminescence properties and decay profiles of Ce:YAlO_3,Mn:YAlO_3,and Ce,Mn:YAlO_3 crystals grown by Czochralski method.The spectroscopic properties show that both Mn~(2+) ions and Mn~(4+) ions exist in Mn:YAlO_3 and Ce,Mn:YAlO_3 crystals.The Mn~(2+) ions have a broad emission band of 60 nm in Mn-doped YAlO_3 crystal at 530 nm.The luminescence spectra also indicate that there is significant energy transfer between Ce~(3+) and Mn~(4+) in Ce,Mn:YAlO_3 crystal.Because of the energy transfer,the first decay component in Ce,Mn:YAlO_3 decreases from 24.5 to 10.8 ns,which is much faster than that of Ce:YAlO_3. 相似文献
8.
Results of cooperative phenomena investigations in the impurity subsystem of lithium niobate crystals doped with Er3+ and co-doped with Yb3+ impurity ions under continuous wave and pulsed excitation at 975 nm and 1064 nm wavelengths are presented. Dependences of some spectroscopic characteristics on the intensity of laser pumping are studied. Based on the pair centers model the analysis of the cooperative luminescence behavior in LiNbO3:Yb3++Er3+ crystals is performed. 相似文献
9.
I. V. Berezovskaya N. P. Efryushina P. A. Rodnyĭ A. S. Voloshinovskiĭ V. P. Dotsenko 《Optics and Spectroscopy》2006,101(6):902-905
The luminescence properties of calcium orthoborate Ca3(BO3)2 doped with cerium are studied upon x-ray (~30 keV) and VUV (3.5–15 eV) synchrotron excitation. The emission bands peaked at 392 and 420 nm are attributed to interconfigurational transitions of Ce3+ ions. The short-wavelength emission band at 340 nm is caused by radiative decay of exciton-like states. The fundamental absorption edge of Ca3(BO3)2 is found to be near 7.1 eV. Based on thermoluminescence data and other information, the behavior of defects in Ca3(BO3)2:Ce3+ is studied. 相似文献
10.
I. N. Ogorodnikov V. A. Pustovarov A. V. Kruzhalov L. I. Isaenko M. Kirm G. Zimmerer 《Physics of the Solid State》2000,42(10):1846-1853
The paper presents the results of a complex investigation into the dynamics of electronic excitations in the CsLiB6O10 crystal (CLBO) by low-temperature luminescence VUV spectroscopy with subnanosecond time resolution under photoexcitation by synchrotron radiation. Strong broad-band low-temperature photoluminescence (PL) of the CLBO crystal has been revealed. Data on the PL decay kinetics, time-resolved PL and PL excitation spectra, and reflectance spectra at 9.3 and 295 K are obtained. It is shown that the intrinsic PL of CsLiB6O10 in the 3.5-eV range is caused by radiative annihilation of self-trapped excitons. The channels of creation and decay of relaxed and unrelaxed excitons in cesium lithium borate are discussed. The band gap of CLBO is estimated as E g≈8.5 eV. A monotonic increase in the excitation efficiency of intrinsic CLBO luminescence at exciting photon energies above 19 eV is identified as the photon multiplication process. 相似文献
11.
12.
A. Lushchik Ch. Lushchik I. Kudryavtseva A. Maaroos F. Savikhin E. Shablonin E. Vasil’chenko 《Optics and Spectroscopy》2011,111(3):434-440
The processes of photon multiplication in insulators have been considered. The luminescence of Tb3+ ions (5
D
3 → 7
F
J
, 5
D
4 → 7
F
J
transitions) upon intracenter excitation, the optical excitation of oxyanions, or the formation of separated electrons and
holes has been studied for CaSO4 doped with Tb3+ and Na+ ions at 6–9 K. An increase in Tb3+ concentration from 0.2 to 4 at % and transition from single Tb3+-Na+ states to centers that contain two or three terbium ions leads to the redistribution of the luminescence intensities in favor
of the 5
D
4 → 7
F
J
transitions and increase in their efficiency due to the possibility of the cooperative 5
D
3 → 5
D
4 and 7
F
6 → 7
F
J
transitions and the 4f
75d
1 → 5
D
3 and 7
F
6 → 5
D
4 transitions in the two- and three-terbium centers. Based on the example of MgO single crystals with highly mobile excitons,
holes, and electrons, the migration of free excitons and holes toward Cr3+ ions in the crystal bulk and their exit from the bulk to the surface have been revealed at 9 K. Surface losses limit the
luminescence quantum yield of MgO:Cr3+, CaSO4:Tb3+, and many other materials. 相似文献
13.
Spatially separated defects created by photons with energies 6–8 eV in alkali-earth fluoride crystals doped with cerium are
investigated with the help of thermoluminescence. Measuring the spectra of creation of Vk and H peaks of thermostimulated luminescence inBaF
2:Ce3+. we demonstrate that photons with energies higher than 6eV induce H centers (self-trapped holes captured by interstitialF ions), whereas the formation of self-trapped holes begins on exposure to photons with energies greater than 7 eV. The influence
of photoionization on theCe
3+ luminescence inBaF
2, SrF2, CaF2, andCeF
3 crystals is investigated in the range of photon energies 4–8 eV. An exponentialCe
3+-emisson decay was observed for excitation energy lying in the range 4–6 eV. Slow and fast decay components were observed
under excitation by photons with energies higher than 6 eV. We believe that the slow and fast components are due to the tunnel
recombination of trapped electrons with hole centers.
A. P. Vinogradov Institute of Geochemistry of the Siberian Branch of the Russian Academy of Sciences. Translated from Izvestiya
Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 43–49, March, 2000. 相似文献
14.
T. T. Basiev M. E. Doroshenko V. V. Osiko A. M. Prokhorov 《Journal of Experimental and Theoretical Physics》2001,93(6):1178-1183
A phenomenon of highly efficient cooperative energy transfer from Ho3+ and Tm3+ ions to two-particle (2Ce3+) cooperative acceptors in crystals of solid solutions of La1?x Ce x F3 is revealed. The rates of cooperative energy transfer in Ho3+→2Ce3+, Tm3+→2Ce3+, and Tb3+→ 2Yb3+ systems are measured, as well as their dependence on the magnitude of the matrix elements of donor transition. 相似文献
15.
16.
Luminescent properties of Tm3+-doped GdYTaO4 are studied for exploring their potential applications in temperature and pressure sensing.Two main emission peaks from 3H4→3H6 transition of Tm3+are investigated.Intensity ratio between the two peaks evolves exponentially with temperature and has a highest sensitivity of 0.014 K?1 at 32 K.The energy difference between the two peaks increases linearly with pressure increasing at a rate of 0.38 meV/GPa.Intensity ratio between the two peaks and their emission lifetimes are also analyzed for discussing the pressure-induced variation of the sample structure.Moreover,Raman spectra recorded under high pressures indicate an isostructural phase transition of GdYTaO4 occurring at 4.46 GPa. 相似文献
17.
The spectra and relaxation kinetics of the anomalous (?? < 10 ns) luminescence of Li6GdB3O9:Ce3+ crystals have been experimentally detected. The time-resolved vacuum ultraviolet spectroscopy study has shown that optical transitions at 6.2 eV, caused by the transfer of an electron from the 4f 1 ground state of Ce3+ to autoionizing states near the conduction band bottom of a crystal, lead to the formation of an impurity-bound exciton with the hole component localized on the 4f state of Ce3+ and the electron localized on states of the conduction band bottom. It has been found that the decay of such an exciton in Li6GdB3O9:Ce3+ occurs through radiative recombination, leading to fast luminescence at 4.25 eV. The energy threshold for the formation of the impurity-bound exciton has been determined. The distribution functions of elementary relaxations over the reaction rate constants H(k), which determine the relaxation kinetics and luminescence quenching processes, have been calculated. 相似文献
18.
B. R. Namozov R. I. Zakharchenya M. P. Korobkov V. V. Mürk 《Physics of the Solid State》1998,40(4):599-600
Optical properties, including luminescence, of scandium-doped α-Al2O3 crystals have been studied in the VUV range. An absorption band associated with the scandium impurity was observed at the
fundamental-absorption edge of crystalline corundum. A strong luminescence band peaking at 5.6 eV, which is most effectively
excited within the 7.7–8.8-eV interval, was found. The kinetic and polarization characteristics of this luminescence were
studied within the temperature range 6–500 K. An excitation model of the impurity complex and the mechanism of its relaxation
are discussed.
Fiz. Tverd. Tela (St. Petersburg) 40, 653–654 (April 1998) 相似文献
19.
We report data on the luminescence spectra associated with photochromic centers in X-ray irradiated calcium fluoride crystals doped with Lu ions. Irradiation in low energy photochromic centers absorption band excites emission, which can be identify with transitions into photochromic centers. Ab initio calculation of absorption spectrum of photochromic center agrees rather well with experimental data. 相似文献
20.
I. N. Ogorodnikov V. A. Pustovarov M. Kirm A. V. Kruzhalov L. I. Isaenko 《Physics of the Solid State》2001,43(8):1454-1463
The dynamics of electron excitations and luminescence of LiB3O5 (LBO) single crystals was studied using low-temperature luminescence vacuum ultraviolet spectroscopy with a subnanosecond time resolution under photoexcitation with synchrotron radiation. The kinetics of the photoluminescence (PL) decay, the time-resolved PL emission spectra, and the time-resolved PL excitation spectra of LBO were measured at 7 and 290 K, respectively. The PL emission bands peaking at 2.7 eV and 3.3 eV were attributed to the radiative transitions of electronic excitations connected with lattice defects of LBO. The intrinsic PL emission bands at 3.6 and 4.2 eV were associated with the radiative annihilation of two kinds of self-trapped electron excitations in LBO. The processes responsible for the formation of localized electron excitations in LBO were discussed and compared with those taking place in wide-gap oxides. 相似文献