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1.
Na0.4Y0.6F2.2:Er3+ (NYF:Er) crystals with an erbium concentration as high as 100 at. % (Na0.4Er0.6F2.2) were grown by the Bridgman-Stockbarger method. The optical spectra were investigated at low (6 K) and room temperatures. It is shown that the absorption spectrum of NYF:Er crystals contains wide bands (790–801 and 965–980 nm) corresponding to the emission range of laser diodes. The peak absorption cross section σa for the band peaked at λ=970.4 nm is 0.15×10?20 cm2. On the basis of the analysis of the absorption and luminescence spectra at low (6 and 12 K) temperatures, the structure of the Stark splitting of erbium levels was determined as a structure of quasi-centers for which Stark components are inhomogeneously broadened. The oscillator strengths of the transitions from the ground state of erbium to excited multiplets were calculated from the absorption spectra measured at T=300 K, and the intensity parameters Ωt were determined by the Judd-Ofelt method: Ω2=1.65×10?20 cm2, Ω4=0.56× 10?20 cm2, and Ω6=1.01×10?20 cm2. These values of the intensity parameters were used to calculate the probabilities of radiative transitions and the branching ratios. The rates of multiphonon nonradiative transitions in NYF: Er were estimated. The luminescence decay kinetics for radiative levels of erbium ions upon their selective excitation by nanosecond laser pulses was studied. The intracenter lifetimes of radiative levels of erbium ions were determined from the luminescence kinetics upon selective ion excitation by low-intensity light in a sample with a low erbium concentration (0.5%). It is demonstrated that, with an increase in temperature from 6 to 300 K, luminescence from the 4 G 11/2, 2 G(H)9/2, and 4 F 9/2 levels is quenched as a result of multiphonon nonradiative transitions. Luminescence from the 4 I 9/2 level is quenched only insignificantly with increasing temperature, and no quenching of luminescence from the 4 I 11/2 and 4 I 13/2 levels is observed. The spectra of steady-state luminescence of NYF:Er(0.5–15%) crystals were investigated upon broadband excitation by UV and UV-visible lamp light and selective time-resolved laser excitation. It is shown that low-lying levels of erbium ions separated by an energy gap smaller than 2500 cm?1 are populated via cascade mechanisms. On the basis of the results obtained, it is concluded that NYF:Er 3+ crystals are promising candidates for active media of tunable diode-pumped lasers. 相似文献
2.
Ca0.89Y0.11F2.11:Er3+ (CYF:Er) crystals with an erbium content of 1–15 at % have been grown. The optical spectra and luminescence kinetics of CYF:Er crystals have been investigated at low (~5 K) and room temperatures. Based on an analysis of the absorption spectra at low temperature, the structure of Stark splitting of erbium levels in CYF:Er crystals is determined. Room-temperature absorption spectra are used to calculate the spectra of absorption cross sections and oscillator strengths of transitions from the erbium ground state to excited multiplets. It is shown that the absorption spectrum of CYF:Er crystals contains broad bands in the ranges of 790–815 and 965–980 nm, which correspond to the range of emission of laser diodes. For the band peaking near 967 nm, the peak absorption cross section is σ abs max = 2.7 × 10?21 cm2. The intensity parameters are determined by the Judd-Ofelt method to be Ω2 = 1.39 × 10?20, Ω4 = 1.34 × 10?20, and Ω6 = 2.24 × 10?20 cm2. The radiative transition probabilities, radiative lifetimes, and branching ratios are calculated with these values. The luminescence decay kinetics from excited erbium levels upon selective excitation is investigated and the experimental lifetimes of the 4F 9/2, 4 S 3/2, and 4 G 11/2 radiative erbium levels are determined. The dependences of multiphonon relaxation rates on the energy gap in CYF:Er crystals are obtained. The rates of nonradiative multiphonon relaxation from radiative erbium levels are determined. 相似文献
3.
Na0.4Y0.6F2.2:Er3+ (NYF:Er3+) crystals with an Er concentration up to 15% were grown by the Bridgman-Stockbarger method. The luminescence kinetics was investigated for a series of NYF:Er3+ crystals (0.5–15% Er), as well as the concentration and temperature quenching of the luminescence from radiative Er levels upon selective laser excitation. It is shown that the luminescence from the 4S3/2 level is quenched significantly with increasing temperature and concentration. The luminescence from the 4G11/2, 2G(H)9/2, 4F9/2, and 4I9/2 levels is quenched mainly due to nonradiative multiphonon transitions. The concentration quenching of the luminescence from the 4I11/2 and 4I13/2 levels was not observed. Possible schemes of the self-quenching of excited levels of erbium are considered and the microparameters and macrorates of self-quenching are estimated by model quantum-mechanical calculation. Based on the comparison of the calculated and experimental self-quenching rates, the most probable mechanisms and schemes of self-quenching are determined. The self-quenching of the 4S3/2 level of erbium was investigated experimentally and theoretically. Good agreement is obtained between the experimental and the calculated kinetic curves and the dependences of the self-quenching rates on Er concentration. It is concluded that NYF:Er3+ crystals are promising as active media for tunable lasers with laser diode pumping. 相似文献
4.
A. P. Skvortsov V. A. Trepakov S. Kapphan A. Dejneka L. Jastrabik 《Physics of the Solid State》2009,51(7):1470-1472
The first results of the study of optical absorption spectra of KTaO3: Er3+ crystals are presented. In the 350–660-nm region, lines are observed deriving from intraconfigurational electronic transitions from the 4 I 15/2 ground state to levels of the 4 F 9/2, 4 S 3/2, 2 H 11/2, 4 F 7/2, 4 F 5/2(4 F 3/2), 2 G 9/2, and 4 G 11/2 excited states of the Er3+ ions. A comprehensive study of transitions to the 4 F 9/2, 4 S 3/2, 2 H 11/2, and 4 F 7/2 levels at 77 K is carried out. The number of lines observed for the above transitions fits the theoretically possible number for ?-? electronic transitions in Er3+ ions in the cubic crystal field. In the case of a differently charged substituted ion, this situation occurs only under nonlocal impurity charge compensation. The energies of the excited state levels for the transitions under study are determined. 相似文献
5.
K. V. Ivanovskikh V. A. Pustovarov B. V. Shul’gin M. Kirm 《Physics of the Solid State》2005,47(8):1446-1449
Time-resolved excitation and emission spectra of SrF2: Er3+ upon selective excitation with synchrotron radiation in the VUV and ultrasoft x-ray ranges at T = 8 K were studied. The VUV luminescence of SrF2: Er3+ derives from high-energy interconfiguration 4f105d-4f11 transitions in the Er3+ ion. The VUV emission spectrum revealed, in addition to the 164.5-nm band (millisecond-range kinetics), a band at 146.4 nm (with a decay time of less than 600 ps). The formation of excitation spectra for the f-f and f-d transitions in the Er3+ ion is discussed. 相似文献
6.
V. N. Makhov T. V. Uvarova M. Kirm S. Vielhauer 《Bulletin of the Lebedev Physics Institute》2016,43(12):348-351
Thermal quenching of interconfigurational 5d-4f luminescence of Er3+ and Tm3+ ions in BaY2F8 crystals is studied in the temperature range of 330–790 K. The quenching temperatures are ~575 and ~550 K for Er3+ and Tm3+, respectively. It is shown that quenching of 5d-4f luminescence of Tm3+ ions is caused by thermally stimulated ionization of 5d electrons to the conduction band. 相似文献
7.
Yu. K. Voron’ko A. V. Malov K. N. Nishchev P. A. Ryabochkina A. A. Sobol S. N. Ushakov 《Optics and Spectroscopy》2007,102(5):722-727
Based on the analysis of the absorption spectra of Er-doped calcium-niobium-gallium garnet (Er:CNGG) crystals according to the Judd-Ofelt theory, the intensity parameters for these crystals are determined to be Θ2 = 3.43 × 10?20 cm2 Θ4 = 1.20 × 10?20 cm2, and Θ6 = 0.58 × 10?20 cm2. The parameters found are compared with the intensity parameters for other laser oxide crystals. Using these intensity parameters, the probabilities of radiative transitions between the energy levels of Er3+ ions in CNGG crystals and the luminescence branching ratios βJJ’ are calculated. From the measured lifetime of the 4 I 11/2 level of Er3+ ions (τ = 626 μs) and the probability of the radiative transition from this level (A = 192 s?1), it is found that about 88% of the excitation energy in the Er:CNGG crystals is nonradiatively transferred from the 4 I 11/2 to the 4 I 13/2 level. It is suggested that an increase in the oscillator strength and in the line strength of the 4 I 15/2 → 2 H 11/2 transition of Er3+ in CNGG crystals, as well as an increase in the intensity parameter Θ2 with respect to the corresponding parameters for other garnet crystals are caused by the existence in CNGG crystals of Er3+ centers with the environment symmetry lower than D 2. 相似文献
8.
Vacuum ultraviolet luminescence of Er3+ ions in LiYF4 and BaY2F8 crystals has been investigated. It is revealed that under excitation by 193 nm radiation from an ArF excimer laser the interconfigurational 5d–4f radiative transitions in Er3+ ions are observed. It is shown that from the LiYF4:Er crystal only the spin-forbidden luminescence (λ = 165 nm) is detected, whereas both the spin-forbidden (λ = 169 nm) and spin-allowed (λ = 160.5 nm) components are observed from the BaY2F8:Er crystal. 相似文献
9.
The absorption, luminescence, and excitation spectra of CaF2, SrF2, and BaF2 crystals with EuF3 or YbF3 impurity have been investigated in the range 1–12 eV. In all cases, strong wide absorption bands (denoted as CT1) were observed at energies below the 4f n -4f n ? 15d absorption threshold of impurity ions. Weaker absorption bands (denoted as CT2) with energies 1.5–2 eV lower than those of the CT1 bands have been found in the spectra of CaF2 and SrF2 crystals with EuF3 or YbF3 impurities. The fine structure of the luminescence spectra of CaF2 crystals with EuF3 impurities has been investigated under excitation in the CT bands. Under excitation in the CT1 band, several Eu centers were observed in the following luminescence spectra: C 4v , O h , and R aggregates. Excitation in the CT2 bands revealed luminescence of only C 4v defects. 相似文献
10.
The absorption and luminescence spectra of neodymium in a binary inorganic solvent—phosphorus oxychloride-antimony pentachloride—are measured. The spectra are analyzed in terms of the Judd-Ofelt theory. The Judd-Ofelt parameters Ωλ, the oscillator strengths of the main absorption bands, the spontaneous emission probabilities, the radiative lifetime, the luminescence quantum yields, and the stimulated emission cross sections for the 4 F 3/2 → 4 I 11/2 laser transition are calculated. 相似文献
11.
Yu. K. Voron’ko E. V. Zharikov D. A. Lis A. V. Popov V. A. Smirnov K. A. Subbotin 《Physics of the Solid State》2008,50(9):1605-1610
Single crystals of double sodium-containing lanthanum and gadolinium molybdates doped with Tm3+ ions were synthesized by the Czochralski method. The spectroscopic properties of these crystals were investigated from the viewpoint of their use as active media in diode-pumped lasers. The polarized spectra of absorption on the 3 H 4 and 3 F 4 levels and the polarized spectra of luminescence due to the 3 F 4-3 H 6 laser transition were recorded, and the lifetimes of the 3 H 4 and 3 F 4 excited states of the Tm3+ ions were determined. The luminescence cross sections were calculated using the Füchtbauer-Ladenburg formula. The simulation of the decay curve of the 3 H 4 excited state according to the Golubov-Konobeev-Sakun method revealed that, in the crystals under investigation, the interaction between Tm3+ ions predominantly occurs through the dipole-dipole mechanism. 相似文献
12.
The absorption spectra of the Er3+ ions embedded in the AlN matrix have been investigated. The admixture of erbium was introduced in bulk AlN crystals by diffusion. The absorption lines, which are associated with the intraconfigurational electronic f–f-transitions from the ground 4 I 15/2-state to the levels of ion Er3+ excited states have been observed in the spectral range of 370–700 nm. The transitions to the state levels 4 F 9/2, 2 H 11/2, 4 F 7/2, 4 F 5/2, 2 H 9/2, and 4 G 11/2 have been investigated in detail at the temperature T = 2 K. The number of the observed lines for these transitions coincides with the theoretically possible one for the electronic f–f-transitions in the ions Er3+, which are in the crystal field with the symmetry below cubic. The narrowness of the observed lines and their number convincingly testify the replacement of preferably one regular crystalline position by erbium ions. The implementation of Er3+ in the Al3+ position with the local symmetry C 3v appears the most probable. The energy positions of the levels of excited states for the investigated transitions have been determined. The diagram of the Er3+ ion energy levels in the AlN crystals has been built. 相似文献
13.
A. M. Tkachuk S. É. Ivanova L. I. Isaenko A. P. Yelisseyev S. Payne R. Solarz R. Page M. Nostrand 《Optics and Spectroscopy》2002,92(1):83-94
Optical spectra, radiative and nonradiative transition intensities, and luminescence kinetics of neodymium-doped potassium-lead double chloride crystals Nd3+:KPb2Cl5, (Nd3+:KPC) are investigated. Crystals were grown by the Stockbarger-Bridgman technique. Experimental studies of absorption and luminescence spectra are performed, intensity parameters are obtained by the Judd-Ofelt method, radiative transition probabilities and branching ratios are calculated, and nonradiative transition probabilities are estimated. Luminescence kinetics of 2 K 13/2, 2 P 3/2, and 4 D 3/2 radiative levels of neodymium under selective excitation in the 355-nm region are studied. 相似文献
14.
Na0.4Y0.6F2.2:Tm3+ crystals with a thulium content from 1 to 100 at % have been grown by the Stockbarger-Bridgman method. The optical spectra of Na0.4Y0.6F2.2:Tm3+ crystals were investigated in detail at room and low (10 K) temperatures, and the luminescence kinetics was analyzed using different excitation methods. The structure of the Stark splitting of thulium levels as “quasi-centers,” characterized by inhomogeneous broadening of the Stark components, is determined from analysis of the absorption spectrum at 10 K. The oscillator strengths of the transitions from the ground state to excited multiplets are determined from the absorption cross-section spectra at 300 K for ten transitions in the range 5000–38 500 cm?1 and seven transitions in the range 5000–28 500 cm?1. The transition intensity parameters Ω t , obtained by the Judd-Ofelt method from the spectra due to the transitions to ten and seven excited levels, were found to be, respectively, (i) Ω2 = 1.89 × 10?20, Ω4 = 2.16 × 10?20, and Ω6 = 1.40 × 10?20 cm2 and (ii) Ω2 = 2.04 × 10?20, Ω4 = 2.01 × 10?20, and Ω6 = 1.44 × 10?20 cm2. These values of the intensity parameters were used to calculate the radiative transition probabilities and branching ratios and to estimate the multiphonon nonradiative transition probabilities for NYF:Tm. The luminescence decay kinetics from thulium radiative levels upon their selective excitation by nanosecond laser pulses has been studied and the lifetimes of thulium radiative levels in NYF crystals have been found. 相似文献
15.
G. M. Shapochkin V. V. Mikhailin S. P. Chernov D. N. Karimov 《Moscow University Physics Bulletin》2009,64(2):141-145
The short-wave transmission spectrum of Na0.4Lu0.6F2.2 with the visible/ultraviolet transmission edge of 8 eV was studied. Absorption spectra of the 4f—5d transitions of the Ce3+ ion in the region of 4–8 eV were studied in Ce3+-doped Na0.4Lu0.6F2.2 single crystals. Luminescence spectra in the ultraviolet and visible spectral regions, luminescence decay kinetics and reflection and luminescence excitation spectra in the visible/ultraviolet and ultraviolet regions (4–20 eV) were investigated at helium and room temperatures. 相似文献
16.
Yu. V. Zorenko A. S. Voloshinovskii G. B. Striganyuk V. I. Gorbenko 《Optics and Spectroscopy》2005,98(4):555-558
The paper reports on a study of exciton luminescence in single crystals (SCs) and single-crystal films (SCFs) of YAlO3, which have substantially different concentrations of vacancy-type and substitutional defects, under excitation by synchrotron radiation near the fundamental absorption edge. The radiative annihilation of excitons in SCFs was shown to occur primarily at regular perovskite lattice sites and to be accompanied by luminescence in a band peaking at λmax = 295 nm with τ = 5.2 ns. In contrast to SCFs, the radiative exciton decay in YAlO3 SCs takes place predominantly near vacancy-type defects (F+ and F centers) and is accompanied by luminescence in the bands at λmax = 350 nm (τ = 2.5 ns) and 440 nm (τ1 = 1.9 ns, τ2 = 30 ms). Photoexcitation in the 175-nm band of YAlO3 SCs revealed photoconversion of the centers F → F+. 相似文献
17.
L. K. Aminov S. I. Nikitin N. I. Silkin R. V. Yusupov 《Physics of the Solid State》2002,44(8):1558-1563
The luminescence spectra of a KZnF3: Tl+ crystal are investigated in the energy range from 4.75 to 5.9 eV at temperatures of 10–300 K upon excitation into the A absorption band (5.7–6.3 eV). At T=300 K, the luminescence spectra exhibit an intense band with a maximum at 5.45 eV, which is attributed to single Tl+ ions substituted for K+ ions. The 5.723-eV intense narrow band observed at T<20 K is assigned to the 3Γ1u-1Γ1g zero-phonon transition, which is weakly allowed by the hyperfine interaction. The luminescence decay is studied as a function of temperature. The main characteristics of the luminescence spectra are adequately described in terms of the semiclassical theory based on the Franck-Condon principle and the Jahn-Teller effect for an excited sp configuration of the Tl+ ion with the use of the parameters obtained earlier from analyzing the absorption spectra of the system under investigation. 相似文献
18.
A. A. Smirnov I. N. Ogorodnikov V. A. Pustovarov L. I. Isaenko V. Yu. Yakovlev 《Optics and Spectroscopy》2008,105(3):377-379
The efficiency of formation and time evolution of radiation-induced structural defects and pulsed luminescence in KPb2Cl5 crystals under the action of a single electron pulse (E = 250 keV, τ = 20 ns) have been investigated. The spectra (1.1–3.8 eV) and relaxation kinetics (time interval 5 × 10?8?5 s) of transient optical absorption and the pulsed cathodoluminescence spectra and decay kinetics (1.4–3.1 eV) have been measured in the temperature range 80–300 K. It is revealed that the induced optical density and its time evolution depend strongly on temperature, and the absorption relaxation time contains several components and reaches several seconds at T = 300 K. The decay kinetics of transient absorption and pulsed cathodoluminescence kinetics have different orders and are controlled by different relaxation processes. 相似文献
19.
Synthetic single crystals of chromium-and lithium-doped forsterite, namely, (Cr,Li): Mg2SiO4, are studied using electron paramagnetic resonance spectroscopy. It is revealed that, apart from the known centers Cr3+(M1) and Cr3+(M2) (with local symmetries Ci and Cs, respectively), these crystals involve two new types of centers with C1 symmetry, namely, Cr3+(M1)′ and Cr3+(M2)′ centers. The standard parameters D and E in a zero magnetic field [zero-field splitting (ZFS) parameters expressed in GHz] and principal components of the g tensor are determined as follows: D=31.35, E=8.28, and g=(1.9797, 1.9801, 1.9759) for Cr3+(M1)′ centers and D=15.171, E=2.283, and g=(1.9747, 1.9769, 1.9710) for Cr3+(M2)′ centers. It is found that the lowsymmetric effect of misalignment of the principal axes of the ZFS and g tensors most clearly manifests itself (i.e., its magnitude reaches 19°) in the case of Cr3+(M2)′ centers. The structural models Cr3+(M1)-Li+(M2) and Cr3+(M2)-Li+(M1) are proposed for the Cr3+(M1)′ and Cr3+(M2)′ centers, respectively. The concentrations of both centers are determined. It is demonstrated that, upon the formation of Cr3+-Li+ ion pairs, the M1 position for chromium appears to be two times more preferable than the M2 position. Reasoning from the results obtained, the R1 line (the 2E → 4A2 transition) observed in the luminescence spectra of (Cr,Li): Mg2SiO4 crystals in the vicinity of 699.6 nm is assigned to the Cr3+(M1)′ center. 相似文献
20.
P. A. Rodnyĭ I. V. Berezovskaya A. S. Voloshinovskii G. B. Stryganyuk A. S. Potapov 《Optics and Spectroscopy》2003,94(4):550-555
Spectral and kinetic characteristics of the luminescence and luminescence excitation spectra of polycrystalline SrB4O7:Pr (1%) and SrB6O10:Pr (1%) samples are studied at 150–170 K. The samples show an intense luminescence band in the vicinity of 405 nm (1 S 0→1 I 6 transitions of Pr3+) and shorter wavelength bands also assigned to transitions from the 1 S 0 level. The main luminescence decay constant is ~2×10?7 s. The excitation spectra of the 1 S 0 luminescence in these crystals are significantly different. The SrB4O7:Pr crystal shows three well-resolved bands at 6.14, 6.55, and 6.91 eV in the region of the 4f 2→4f 15d transitions and a complex structure in the region of interband transitions (7.1–20 eV), whereas the SrB6O10:Pr crystal shows a weakly structured band at 6.31 eV and no excitation in the region of the interband transitions. The physical mechanisms that may be responsible for the observed features of the spectra are discussed. 相似文献