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目前,稀土无机发光材料在激光、光通讯、平板显示、荧光生物标记和纳米光电子器件等领域具有广泛的应用前景.稀土离子(从Ce到Yb)是一类性能优异的结构和光谱探针,其在不同介质材料中的光学性能主要取决于其局域态的电子结构和激发态动力学.对稀土发光材料开展深入的光学和光电子学基础研究有助于发现新颖的光学性能或开辟新的应用领域.依托研制的低温高分辨激光光谱和上转换量子产率等仪器,本课题组致力于稀土无机发光材料电子结构与性能研究,近年来在发光材料的控制合成、电子结构、光学性能及生物应用等方面取得了系列重要结果.这些研究有望加快实现稀土无机发光材料在生物应用的突破,实现稀土资源的高值利用. 相似文献
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纺锤形铁黄α—FeOOH微晶合成动力学研究 总被引:2,自引:0,他引:2
本文对纺锤形α-FeOOH微晶合成动力学过程进行了研究,利用复相反应经验动力学方程,考察了初始浓度,反应温度和空气流量对Fe(OH)2-FeCO3悬浮液氧化速率的影响,确定了α-FeOOH成核-生长速率方程,证实了晶粒生长阶段存在溶解-氧化的动态平衡,根据活化能大小,推断相界面氧化反应为该相反应的控制步骤,还对α-FeOOH成核生长微观机理作了初步探讨。 相似文献
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According to Judd-Ofelt parameter calculation and energy transfer theory, the cross-relaxation process of the Tm3+ ions is investigated. A four-level system of coupled rate equations is established to study the fluorescence dynamics of Tm3+ in LiYF4 crystal. Attentions are focused on the upconversion luminescence 1G4→3H6 (483.0 nm) in Tm3+:LiYF4. The relationship between the avalanche properties (critical pump rate, fluorescence intensity and buildup time) originated by resonant excited state absorption and the doped Tm3+ concentration is discussed, and some useful conclusions are drawn. 相似文献
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提出了四能级耦合系统的光子雪崩上转换模型,首先从理论上分析了光子雪崩产生的条件,给出了雪崩阈值以及在低于或高于阈值条件下荧光强度随时间变化关系;再将该模型结合数值分析应用于Tm^3+:LiYF4晶体这一列,理论分析结果与实验基本一致。因此应用此模型及其理论结果将有助于探索新型光子雪崩上转换材料。 相似文献
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GROUP-CHAIN SCHEME ANALYSIS OF THE ENERGY LEVELS AND MAGNETIC PROPERTIES OF Nd3+ IN LiYF4 CRYSTAL
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Based on the analysis of group-chain scheme, the crystal-field-level fitting of Nd3+: LiYF4 has been carried out, in which the Nd3+ inos occupy positions with site symmetry S4. The RMS deviation of energy-level fitting is 12.8cm-1. Using the obtained wave functions, g-factors of the fround state are calculated,which are g∥=2.067 and g⊥=2.631, in good agreement with the experimental values(g∥=1.978 and g⊥=2.554). The method proposed turns out to be effective in the study of spectral properties of localized centres in laser crystals. 相似文献
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Structure and luminescence of Ca2Si5N8:Eu^2+ phosphor for warm white light-emitting diodes
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We have synthesized Ca 2 Si 5 N 8:Eu 2+ phosphor through a solid-state reaction and investigated its structural and luminescent properties.Our Rietveld refinement of the crystal structure of Ca 1.9 Eu 0.1 Si 5 N 8 reveals that Eu atoms substituting for Ca atoms occupy two crystallographic positions.Between 10 K and 300 K,Ca 2 Si 5 N 8:Eu 2+ phosphor shows a broad red emission band centred at ~1.97 eV-2.01 eV.The gravity centre of the excitation band is located at 3.0 eV-3.31 eV.The centroid shift of the 5d levels of Eu 2+ is determined to be ~1.17 eV,and the red-shift of the lowest absorption band to be ~ 0.54 eV due to the crystal field splitting.We have analysed the temperature dependence of PL by using a configuration coordinate model.The Huang-Rhys parameter S=6.0,the phonon energy ν=52 meV,and the Stokes shift S=0.57 eV are obtained.The emission intensity maximum occurring at ~200 K can be explained by a trapping effect.Both photoluminescence (PL) emission intensity and decay time decrease with temperature increasing beyond 200 K due to the non-radiative process. 相似文献
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