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1.
We have studied the photoexcitation and luminescence spectra of Bi2WO6, Y2WO6 and Y2WO6:Bi ceramics. We used the Alentsev-Fock method to decompose the spectra into elementary components. The emission bands with
maximum at 2.93 eV in the luminescence spectrum of Bi2WO6, 3.02 eV in the luminescence spectrum of Y2WO6, and 2.95 eV in the luminescence spectrum of Y2WO6:Bi are assigned to luminescence of self-localized Frenkel excitons. The bands with maxima at 2.35 eV and 1.90 eV in the spectrum
of Bi2WO6, 2.25 eV and 1.75 eV in the spectrum of Y2WO6, and 2.35 eV and 1.85 eV in the spectrum of Y2WO6:Bi are connected with oxygen vacancies.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 5, pp. 688–691, September–October, 2007. 相似文献
2.
Sc2O3 luminescence spectra are studied. The spectra are separated into elementary bands by the Alentsev–Fock method. It is established
that the luminescence spectra consist of a number of overlapping bands with maxima at 3.5; 3.05; 2.65; 2.35, and 2.05 eV.
The band at 3.5 eV is interpreted as emission of self-localized excitons, and the other bands, as defect-center recombination.
L’vov State University, 50, Dragomanov St., L’vov, 290005, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol.
64, No. 6, pp. 776–778, November–December, 1997. 相似文献
3.
The luminescence spectra of thin Bi2W2O9 films have been investigated. The spectra were separated into elementary components by the Alentsev–Fock method. The radiation band with a maximum at 2.43 eV in the luminescence spectrum of Bi2W2O9 has been assigned to the Frenkel autolocalized excitons. The luminescence bands with maxima at 2.10 and 1.90 eV have been assigned to the emission of the centers whose energy levels are located in the forbidden band. The luminescence of the Bi2W2O9 films is due to the emission of the WO6 complex. 相似文献
4.
Heat-stimulated luminescence (HSL) of x-ray-irradiated Y2O3, Y2O3:Eu, and Sc2O3 ceramics samples is investigated. An analysis of the form of the elementary contours making the HSL curves shows that recombination
processes at the HSL peaks with maxima at 110, 122, 176, 185, 200, and 247 K in Y2O3. ceramics and with those at 121, 136, 200, 215, and 221 K in Sc2O3 are described in terms of linear kinetics. The spectral composition of the HSL of the ceramic obtained is studied. Some methods
are employed to determine the activation energies and frequency factors corresponding to the HSL peaks. It is established
that the recombination processes occurring upon release of the trapping sites in the Y2O3 and Sc2O3 ceramic samples are conditioned by diffusion-controlled tunneling recombination due to heat-stumulated migration of Vk-centers.
L'vov I. Franko State University, 50, Dragomanov St., L'vov, 290005, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii,
Vol. 64, No. 3, pp. 348–353, May–June, 1997. 相似文献
5.
6.
An investigation is made of the luminescence spectra of Me2WO6 ceramics (Me=Y, Sc, Bi). The spectra were decomposed into elementary components by the Alentsev—Fock method. Radiation hands
with a maximum at 3.02 eV in the Y2WO6 luminescence spectrum, at 2.8 eV in the ScWO6 spectrum, and at 2.93 eV in the Bi2WO6 spectrum are assigned to the light emission of self-localized Frenkel excitons. The bands with maxima at 2.25 and 1.75 eV
in the Y2WO6 spectrum, at 2.36 and 1.9 eV in the Sc2WO6 spectrum, and at 2.35 and 1.9 eV in the Bi2WO6 spectrum are related to oxygen vacancies.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol 67, No. 2, pp. 273–275, March–April, 2000. 相似文献
7.
Thermostimulated luminescence (TSL) of PbWO4, Bi2WO6, and Y2WO6 ceramics on x-ray excitation is investigated. The spectral luminosity of the thermostimulated luminescence is analyzed. The thermal activation energies conforming to the corresponding thermostimulated luminescence peaks are determined. It is established that on emptying trapping centers radiative recombination occurs at the intrinsic-luminescence centers associated with tungsten-oxygen complexes WO4
2–. 相似文献
8.
O. M. Bordun 《Journal of Applied Spectroscopy》1998,65(1):149-151
Luminescence spectra of thin films of PbWO4 and Bi2WO6 are invesigated. The Alentsev-Fock method is used to separate the spectra into elementary components. The emission bands
with maxima at 2.8 eV in PbWO4 and at 2.93 eV in Bi2WO6 luminescence spectra are interpreted as the emission of self-localized Frenkel excitons. The bands with maxima at 2.35 and
1.75 eV in PbWO4 and at 2.35 and 1.9 eV in Bi2WO6 are related to oxygen vacancies.
L’vov State University, 50, Dragomanov St., L'vov, 290005, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol.
65, No. 1, pp. 143–145, January–February, 1998. 相似文献
9.
Luminescence spectra for isostructural Y2SiO5 and Y2GeO5 are investigated. The spectra are resolved into elementary components by the Alentsev—Fock method. Bands with maxima in regions
of 2.6, 2.3, and 2.05 eV in the spectra of Y2SiO5 luminescence and in regions of 2.55, 2.25, and 2.0 eV in the spectra of Y2GeO5 luminescence are considered as radiative recombination of excited associative donor-acceptor Y3+−O2− pairs. The indicated bands are related to certain distances between yttrium (the donor) and oxygen (the acceptor). A band
with a maximum of 2.95 eV in Y2SiO5 and 3.0 eV in Y2GeO5 occurs in recombination of electrons with holes trapped by an anionic sublattice.
I. Franko L’vov State University, 50, Dragomanov St., L’vov, 290005, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii,
Vol. 65, No. 4, pp. 528–531, July–August, 1998. 相似文献
10.
The pressure dependence of various phonon modes has been investigated through the ferro-paraelectric phase transition. Most
mode frequencies harden before levelling off above the phase transition. Mode Grüneisen parameters are estimated from the
pressure dependence of phonon frequencies. 相似文献
11.
V. V. Pologrudov 《Journal of Applied Spectroscopy》1995,62(3):582-584
Irkutsk State University, 20, Gagarin Av., Irkutsk, 664003, Russia. Translated from Zhurnal Prikladnoi Spektroskopii, Vol.
62, No. 3, pp. 215–217, May–June, 1995. 相似文献
12.
采用固相反应法合成了组成为Ca1-xEuxSi2O2N2的Eu2+掺杂CaSi2O2N2荧光粉.通过荧光光谱对样品的发光性能进行了研究,发现Eu2+掺杂CaSi2O2N2荧光粉发射光谱为宽波段的单峰结构,主要包含绿光和黄光区,发射峰在556~568 nm.从发射光谱的宽带特征来看,CaSi2O2N2:Eu2+的发射主要对应着Eu2+离子4f65d→4f7跃迁.从激发光谱所覆盖的范围还可以看到,样品可以有效的被UV蓝-光激发,这意味着该类荧光粉在白光LED方面有可能得到广泛的应用.另外,样品的发光性能与激发离子的浓度有着很大关系.激发离子浓度增大时,发射光谱会发生明显红移.利用这一性质,可以通过改变Eu2+浓度来调节荧光粉的发光范围,从而满足不同场合的需要.同时,Eu2+浓度提高,样品发射光谱的强度也会随之增强,在x=0.06时发射强度达到最大值,之后继续增加Eu2+浓度,强度不仅没有增加反而降低,即出现浓度猝灭现象. 相似文献
13.
Brian E. Trice 《光谱学快报》2013,46(2):333-348
We report a laser spectroscopic investigation of saturation effects in the spectra and dynamics of Eu2O3. The saturation effects occur at high laser intensity and appear as dips in the center of the fluorescence excitation lines and as a shortening of the 5D0 excited‐state decay curve. The saturation effects are observed in nanoparticles, micrometer‐sized particles, and a fused crystal of monoclinic‐phase Eu2O3 and in micrometer‐sized particles of cubic‐phase Eu2O3. We attribute the mechanism of the nonlinear luminescence quenching to upconversion by energy transfer. 相似文献
14.
In the present work we investigate the tunneling luminescence (TL) of Y2O3, Y2O3:Eu, and Sc2O3 ceramics. From an analysis of the decay kinetics of the TL it is established that the recombinational processes are described
by a model involving recombination with a complex interaction. In addition, using the method of partial light sums, we show
that in the ceramics investigated the mechanisms of TL are the same and the majority of radiation-induced defects in pairs
are removed to distances exceeding the radius of effective tunneling transitions with a time constant of 10–100 sec. In the
Y2O3:Eu ceramics the distances between defects decrease. TL occurs in pairs whose electron component is F-centers that are thermally
released at 176 K in the Y2O3 ceramics and 200 K in the Sc2O3 ceramics. The hole components of tunneling pairs are associated with centers that are thermally released at 110 and 122 K
in the Y2O3 ceramics and at 121 and 146 K in the Sc2O3 ceramics.
To whom correspondence should be addressed.
I. Franko Lvov State University, 50, Dragomanov Str., Lvov, 290005, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii,
Vol. 66, No. 5, pp. 649–651, September–October, 1999. 相似文献
15.
For an ensemble of different types of luminescence centers with overlapping absorption bands, with no restrictions on the
optical densities, we have obtained relations describing the luminescence excitation spectra for each type of center. We consider
transformations of the relations in some limiting cases. We suggest a procedure for using the equations obtained to determine
the characteristics of the luminescence centers. Some of these procedures have been experimentally implemented in study of
intrinsic radiation color centers in lithium fluoride crystals. We have determined the ratios of the luminescence quantum
yields for F2 and F3+ color centers, and we have observed that a major role is played by nonradiative transitions in deactivation of the first
excited singlet state of F3+ centers.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 3, pp. 365–371, May–June, 2008. 相似文献
16.
E. M. Shishonok 《Journal of Applied Spectroscopy》2007,74(2):272-277
Complex and multiband photoluminescence spectra for GB and HBN centers in single crystals of cubic boron nitride (cBN) were
recorded in the wavelength ranges 385–400 nm and 365–395 nm and the nature of these centers was studied. The use of models
involving resonance vibrations and strongly shifted configuration diagrams for the electronic ground state and excited state
made it possible to associate formation of the GB-1 center with the presence of tungsten impurity in cBN. It was established
that the HBN band in the 300–350 nm range of the cathodoluminescence spectra of cBN polycrystals, single crystals, and micropowders
is associated with luminescence centers present in microinclusions of graphite-like boron nitride (hBN). The nature of the
hBN band is tentatively interpreted within the model of recombination of donor and acceptor defects in hBN: respectively nitrogen
vacancies and carbon atoms in positions substituting for nitrogen.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 2, pp. 241–246, March–April, 2007. 相似文献
17.
通过高温固相法制备出Sr0.98-xAl2O4:0.02Eu2+,xTm3+(x=0,0.01,0.02,0.03,0.04,0.05)系列样品,并对其光激励和热释光性能进行了研究。在SrAl2O4:Eu2+原有陷阱能级结构的基础上,通过Tm3+的掺杂引入了更深的陷阱TB,并增加原有陷阱TA浓度,进而优化了材料的光存储容量及光激励特性。对比研究了系列样品的初始光激励发光强度和热释光强度随着Tm3+掺杂量的变化规律,证实陷阱TB为光激励发光提供了有效俘获中心。当Tm3+的掺杂摩尔分数x=0.03时,材料中的陷阱TB的浓度达到最高值,同时光激励发光强度最大。对比Tm3+共掺前后热释光图谱,通过Chen's半宽法计算出了引入陷阱TB的陷阱深度。实验结果证实材料中TB的浓度对其光激励发光性能起着决定性的作用。在980 nm激发下,由深陷阱TB释放出来的电子可以再次被浅陷阱TA俘获,这种浅陷阱TA的再俘获效应在光激励发光过程中表现为光激励余辉现象。 相似文献
18.
R. A. Brand P. Sen Ch. Sauer J. -P. Sanchez A. Rojek W. Zinn 《Hyperfine Interactions》1990,55(1-4):1243-1248
The valence of Bi and its substituents Sn and Sb are investigated in the high temperature superconductor (Bi0.8X0.15Sb0.05)2Sr2Ca2Cu3Oy (often denoted 2223) where X=Pb or Sn. Pb and Sn are isoelectronic with the valence states 2+ and 4+; Bi and Sb are as well with valence states 3+ and 5+. The valence state of Sn and Sb has been obtained from Mössbauer spectroscopy: they exist in the high charge states 4+ and 5+ respectively. Sn, Sb, and presumably Pb, take on the high valence state, and so furnish electrons to the conduction band. This is probably the reason why, although the (Pb, Sb)-doping aids in stabilizing the 2223 crystal structure, it is detremental to the electronic properties which lead to the superconducting phase. The valence state of Bi has been studied using X-ray photoelectron spectroscopy (XPS). These results show clearly that the Bi-based superconductor has a metal-like density of states at the Fermi level, and that the valence in the (Pb, Sb)-doped compounds is less than 3. This very surprising change in valence will have a profound effect on the superconducting properties, and is probably associated with the high valent states of Pb, Sn and Sb. 相似文献
19.
The luminescence spectra of thin films of PbWO4 and Bi2WO6 were investigated. It is shown that these spectra are similar and that they consist of three individual bands in the blue (2.80 eV PbWO4 and 2.93 eV Bi2WO6), green (2.35 eV PbWO4 and Bi2WO6), and red (1.75 eV PbWO4 and 1.90 eV Bi2WO6) spectral regions. The differences in the nature of the absorption centers of excitation energy are established. The distinguishing features displayed by the temperature dependences of the individual emission bands in the PbWO4 films are explained by energy migration between emission centers via transfer of free carriers through the conduction and valence bands. 相似文献
20.
Yu. V. Zorenko R. M. Turchak T. I. Voznyak Yu. B. Mamai 《Journal of Applied Spectroscopy》2006,73(3):406-410
We have used the Bridgman method to grow CsBr:Eu2+ single crystals, adding an activator to the mix in the form of Eu2O3 in amounts of 0.0125, 0.0250, and 0.0500 mole %. At T = 300 K, we studied the absorption spectra, the photoluminescence (PL)
spectra, and the photostimulated luminescence (PSL) spectra of the grown crystals. We have established that the structure
of the photoluminescence and photostimulated luminescence centers in crystals grown from the CsBr:Eu2O3 mix includes isolated dipole centers Eu2+-VCs, emitting in bands with maxima at 432 nm and 455 nm respectively, and in crystals grown at activator concentrations of 0.025
and 0.050 mole % they also include aggregate centers (AC) based on CsEuBr3 nanocrystals with emission bands at 515 m and 523 nm. We have shown that the maximum concentration of aggregate centers of
the CsEuBr3 nanocrystal type in CsBr:Eu2+ crystals is achieved for an activator content in the mix within the range 0.01–0.05 mole %.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 3, pp. 359–362, May–June, 2006. 相似文献