Impurity Cu+ centers in LiF single crystals

LiF single crystals with copper impurity (0.0004–0.002%) have been grown by the Czochralski method and investigated. The luminescence, excitation, and optical absorption spectra have been recorded. The luminescence spectrum contains a band at 450 nm upon 250-nm excitation. This band is attributed to Cu⁺ centers in the samples grown. The mechanisms of capture and recombination during thermoluminescence are considered.     

Cu掺杂无水芒硝的光致发光特性

在气温1 100℃下,将纯天然无水芒硝(Na2SO4)和Cu的混合粉末加热20 min,制备了Na2SO4:Cu发光材料.在室温中测量了光致发光谱.通过实验结果发现发射光谱形状依赖于激发波长,在260nm激发下的发射光谱是由峰值位于430 nm处的宽带谱构成,所得到的宽带谱归属于Cu+内电子的3d94s→3d10跃迁....     

用巯基乙酸作稳定剂制备CdSe纳米晶的光学性质

以巯基乙酸为稳定剂制备了CdSe纳米晶，通过尺寸选择沉淀得到2nm到3nm之间不同尺寸的纳米晶，利用室温光吸收，光致发光（PL）和光致发光激发（PLE）谱来研究了CdSe纳米团簇的光学性质。紫外－可见吸收谱给了具有清晰激光特征的尖锐吸收边，这表明样品的尺寸分布很窄。光致发光研究表明，样品有两个发射带，一个具有较高能量位于吸收边，来自电子－空穴对从最低激发态能级弛豫后的辐射复合，另一个低能发射带归属于基质与纳米晶界面存在的俘获中心。PLE谱中有2个吸收带，分别是S－S和P－P跃迁。最后还给出了不同激发能量下的发光特性。     

温度梯度法生长的Ce: YAlOZr3高温闪烁晶体的光谱分析

采用温度梯度法生长了熔体掺杂Ce浓度为1at%的YAlO3晶体，对于其吸收光谱、荧光光谱和x射线激发发射谱进行了表征分析.根据吸收光谱提出了一个色心模型，从而成功的解释了为什么刚生长出的晶体为粉红色，而分别经氢气和空气在1400℃退火后均能变为无色的现象和退火以后吸收光谱发生的显著变化.温度梯度法生长的Ce:YAP在330nm处存在着一定程度的自吸收和自激发.光致激发发射谱的发射主峰在368nm，而x射线激发发射谱的主发射峰红移至391nm，这表明在x射线激发下，晶体对发射光的自吸收将会减少.另外在x射线 关键词： 温度梯度法 Ce: YAP 色心 光谱     

LaOBr:Ce,Tb中Ce3+对Tb3+发光的影响

近年来人们对LaOBr:Tb的合成及其发光特性的研究日益增多。LaOBr:Tb不仅是良好的X光增感屏材料,也是较好的阴极射线发光材料。为了进一步提高它的亮度,降低了b的含量(因Tb很贵),寻求LaOBr中Tb3+发光的敏化剂是很重要的。     

水热法制备YVO_4:Eu~(3+)的热处理及其发光性能

用水热法制备的YVO4:Eu3+分别在400～800℃下进行热处理,研究了所得样品的结构及其发光性能。实验结果表明:所得样品都为单相结构,随着热处理温度的升高,样品的结晶度变好,颗粒变大。在紫外光谱范围,YVO4:Eu3+的激发光谱由VO43-的吸收带和Eu3+的电荷迁移带组成。在真空紫外(VUV),激发光谱由基质吸收,Y3+、O2-的电荷迁移带组成。发射光谱均为Eu3+的5D0→7FJ(J=1,2,4)跃迁。紫外和真空紫外激发下,样品的发光强度比未经过热处理的样品有显著增强,归因于样品的结晶度的提高和OH-、VO43-等发光猝灭离子的去除。     

Luminescence of thulium-activated cubic boron nitride

Under high pressure and temperature conditions, we have obtained samples of thulium-activated cubic boron nitride in the form of micropowders, ceramics, and polycrystals activated by thulium in the presence of aluminum. We studied the cathodoluminescence (CL), photoluminescence (PL), and photoluminescence excitation spectra of the samples. In the luminescence spectra we observe structured bands with maxima at ∼370, ∼475, ∼660, and ∼ 800 nm, assigned to electronic transitions in the triply charged thulium ions. We have established that the most efficient method for excitation of “blue” luminescence at ∼475 nm for thulium ions in cBN is excitation by an electron beam. The cBN samples synthesized in the presence of Al have photoluminescence spectra with a more complex structure compared with samples not containing Al, with the band of dominant intensity at about 660 nm. Hypothetically, this is a consequence of incorporation of thulium ions into the crystalline phases cBN and AlN, which are equally likely to be formed during synthesis. The observed photoluminescence spectrum of the indicated samples is the superposition of the photoluminescence spectra of the Tm³⁺ ions located in the crystal fields of cBN and AlN of different symmetries. The presence in the photoluminescence excitation spectra (at 450, 490, and 660 nm) of structure, with features at wavelengths shorter than the excited photoluminescence, suggests a nonresonant mechanism for its excitation. We have established that luminescence of Tm³⁺ ions is less intense than for other rare earth elements incorporated into cubic boron nitride. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 4, pp. 547–555, July–August, 2008.     

稀土氟碳酸盐矿物的光致发光谱和吸收谱研究

测定并讨论了产自四川冕宁矿区的氟碳铈矿和产自内蒙白云鄂博稀土矿区的黄河矿、氟碳钙铈矿、氟碳铈钡矿的光致发光谱。结果表明,稀土氟碳酸盐矿物在488.0nm和514.5nm激光激发下的光致发光中心是Nd3+,发光谱中的所有谱带均出自Nd3+的辐射跃迁。在488.0nm激光激发下,稀土氟碳酸盐矿物在495nm到733nm谱区的发光谱带强而尖锐,但在514.5nm激光激发下,这个谱区的谱带明显变弱或消失,转而出现783nm到907nm谱区的强发光谱带。可见光吸收谱表明稀土氟碳酸盐矿物对可见光的吸收也与矿物中的Nd3+有关。     

Specific features of absorption and luminescence in CsBr: EuOBr crystals

The specific features of the absorption, photoluminescence, x-ray luminescence, thermally stimulated luminescence, and photostimulated luminescence spectra of CsBr: Eu²⁺ single crystals grown using the Bridgman method are investigated in the temperature range 80–500 K at the highest possible dopant content (0.1–0.4 mol % EuOBr in the batch) required for preparing perfect crystals. It is shown that an increase in the dopant content leads to a broadening of the absorption and photoluminescence excitation bands with maxima at wavelengths of 250 and 350 nm due to the interconfigurational transitions 4f⁷(⁸S_7/2) → 4f⁶5d(e _g , t_2g) in Eu²⁺ ions. The photoluminescence and photostimulated luminescence spectra of CsBr: EuOBr single crystals (0.1–0.4 mol % EuOBr) contain a band at a wavelength of λ_max=450 nm and bands at wavelengths of λ_max=508–523 and 436 nm. The last two bands are assigned to Eu²⁺-V_Cs isolated dipole centers and Eu²⁺-containing aggregate centers, respectively. It is revealed that the intensity of the luminescence associated with the aggregate centers (λ_max=508–523 nm) is maximum at an EuOBr content of less than or equal to 0.1 mol % and decreases with an increase in the dopant content. The possibility of forming CsEuBr₃-type nanocrystals that are responsible for the green luminescence observed at a wavelength λ_max=508–523 nm in CsBr: Eu crystals is discussed. The intensity of photostimulated luminescence in the CsBr: EuOBr crystals irradiated with x-ray photons is found to increase as the dopant content increases. It is demonstrated that CsBr: EuOBr crystals at a dopant content in the range 0.3–0.4 mol % can be used as x-ray storage phosphors for visualizing x-ray images with high spatial resolution.     

钨酸锌晶体的受激拉曼散射和光致发光研究

采用皮秒532nm 激光激发，研究了ZnWO₄晶体的受激拉曼散射和本征荧光发射.在SRS光谱中观察到一级(558.7nm)和二级(588.6nm)斯托克斯光，线宽分别为130和77cm^－1, 一级斯托克斯光的抽运阈值为6.8mJ.在532nm激光抽运下ZnWO₄晶体的荧光光谱呈现出由能量为2.30，2.45和2.83eV的3个高斯分量组成的独特结构.光致发光表明晶体具有从400nm到650nm的宽带本征发光，其峰值波长为472.0nm，相应于钨氧之间的辐射跃迁. 关键词： 晶体 钨酸锌 受激拉曼散射 闪烁体     

Luminescence centers in phosphorus-doped Cd1−xMgxTe mixed crystals

The emission and excitation spectra of P-doped Cd_1?xMg_xTe (x ? 0.45) mixed crystals have been measured over the temperature range of 300 ～ 4.2 K to reinvestigate the photoluminescence process of two broad emission bands; the 690 nm band of the as- grown crystals and the 610 nm band of the annealed crystal. The excitation spectrum of each band has a characteristic peak at 550 nm near the absorption edge of this crystal. Together with the data of the decay characteristic and the halfwidth of each band, we discuss the difference in the recombination process when the crystal is excited under two different radiation at 365 and 570 nm (close to the 550 nm radiation). It is concluded that both emission bands arise from donor-acceptor pairs and a localized center or self- activated center; the associated pair is V_Cd-interstitial P in the as-grown and V_Te ? P_Te in the annealed crystal.     

CaLuBO4∶Tb^3+荧光粉的制备及发光性质

采用高温固相反应法合成了不同Tb^3+掺杂浓度的CaLuBO4∶xTb^3+荧光粉,研究了样品的晶体结构和发光性质。在紫外光激发下,样品的发射光谱由Tb3+离子的5D3→7FJ(J=6,5,4)和5D4→7FJ′(J′=6,5,4,3)特征发射组成,其中位于545 nm和554 nm附近的5D4→7F5跃迁发射强度最大。荧光粉的激发光谱是由位于紫外区的Tb3+的4f-5d和f-f跃迁构成的。研究了Tb3+浓度对样品发光性质的影响。测量并分析了CaLuBO4∶xTb^3+荧光粉的5D3能级和5D4能级荧光寿命。结果表明,CaLuBO4∶xTb^3+是一种适于紫外激发的新型黄绿光荧光粉。     

Dy3+掺杂NaYF4纳米粒子的制备及其上转换发光性质

制备了Dy³⁺掺杂 NaYF₄上转换发光纳米晶体,通过X射线衍射(XRD)、扫描电子显微镜(SEM)、荧光(FL)光谱、红外光谱仪(FT-IR)对合成样品的结构、形貌和发光性能进行表征。探讨了稀土离子掺杂浓度和焙烧温度对NaYF₄∶Dy³⁺纳米晶的结构、形貌和发光的影响。在776 nm红外光下激发样品,出现479,574 nm上转换发射峰,实现了蓝、绿上转换发光。绿光来自于Dy³⁺的⁴F_9/2→⁶H_13/2跃迁,蓝光是由Dy³⁺的⁴F_9/2→ ⁶H_15/2跃迁产生的。     

Characterization of ZnS nanoparticles synthesized by co-precipitation method

ZnS nanoparticles are prepared by homogeneous chemical co-precipitation method using EDTA as a stabilizer and capping agent. The structural, morphological, and optical properties of as-synthesized nanoparticles are investigated using x-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, ultraviolet-visible(UV-Vis)absorption, and photoluminescence spectroscopy. The x-ray diffraction pattern exhibits a zinc-blended crystal structure at room temperature. The average particle size of the nanoparticles from the scanning electron microscopy image is about50 nm. The ultraviolet absorption spectrum shows the blue shift in the band gap due to the quantum confinement effect.The photoluminescence spectrum of Zn S nanoparticles shows a blue visible spectrum.     

偏硅酸钙中Ce3+的发光性质

制备了Ce3+激活的CaSiO3磷光体。在77K和室温下研究讨论了它们的激发和发射光谱以及荧光寿命等光学性质,分析了结构和电荷补偿剂的影响。在UV或CR激发下,Ce3+发射较强的蓝紫光,峰值为396nm。室温下,Ce3+离子的荧光寿命大约为30ns。     

Photoluminescence of CaGa<Subscript>2</Subscript>S<Subscript>4</Subscript>:Pr Polycrystals

The photoluminescence (PL) and PL excitation spectra of CaGa₂S₄ polycrystals doped with praseodymium are studied in the regions of the activator absorption and the fundamental absorption of the host. It is found that the PL excitation spectrum consists of two regions: broadband absorption in the range of 200-380 nm corresponding to the fundamental absorption of the host and the narrow-band absorption of the dopant in the range of 430–515 nm. The luminescence spectra are different for different excitation wave-lengths, which occurs because Pr³⁺ ions substitute divalent cations occupying different crystallographic positions in the host crystal lattice.     

水热法祖母绿激光晶体的光谱性质研究

报道了温差水热法生长的祖母绿激光晶体(Cr3+:Be3Al2Si6O18)的光学参量特点.通过对祖母绿晶体的吸收光谱和荧光光谱的测量,计算了晶体场强度Dq、Racah参量B和C, Dq/B≈2.3,说明了祖母绿晶体中的Cr3+离子处于中等晶场.室温下的荧光光谱特点显示4T2→4A2的跃迁为700～840nm的宽带辐射跃迁.此外该晶体的有效声子能量h－ω=409.6cm－1,Huang-Rhys因子S=3.5较小,说明祖母绿的电-声子耦合作用较弱.     

掺铥钨酸盐晶体的光谱研究

采用丘克拉斯基法生长出Tm3+:BaWO4单晶,并在室温下测量了掺铥钨酸钡晶体的吸收光谱。Tm3+:BaWO4晶体在268nm和362nm光源激发下,可以分别观测到位于477.2 nm(1G4→3H6)和455.5nm(1D2→3F4)的可见荧光。本文还报道了在Nd:YAG激光器产生波长1.06μm强脉冲激光激发ZnWO4:Tm3+单晶时,测得Tm3+离子1G4至3H6跃迁的波长在484 nm范围的蓝色上转换荧光光谱。     

Eu2+在磷酸镧中的发光及Ce3+→Eu2+的能量传递

采用高温固相反应合成了LaPO₄:Eu²⁺和LaPO₄:Ce³⁺,Eu²⁺样品,报道了Eu²⁺在LaPO₄中的发光性质和Ce³⁺→Eu²⁺的能量传递现象。文中探讨了Ce³⁺→Eu²⁺的能量传递机理,根据Dexter电多极相互作用的理论证明其为偶极子偶极子相互作用的共振能量传递。     

Luminescence of Molecules with Internal Charge Transfer upon Longwave Excitation

We have studied the spectral properties of luminescence of laurdan molecules in glycerin upon excitation at the red edge of the absorption band at different temperatures. The most significant red-wave shift of the spectra (10 nm) for the longwave band of dual fluorescence is observed depending on the excitation wavelength at a low temperature of 260 K when a solvent forms a fairly rigid matrix. At the same time, at increased temperatures of up to 370 K a small bathochromic shift and a change in the shape of the luminescence bands are also recorded reliably. Changes in the excitation spectra were observed when luminescence was recorded in the bands of the LE- and CT states. The difference spectrum responsible for the additional absorption that does not make a contribution to the longwave luminescence component has been isolated. The decay kinetics of both luminescence components have been measured and their expansions in decay constants have been analyzed. The experimental dependences obtained point to the complex mechanism of inhomogeneous broadening of spectra.