992 resultados para JUDD-OFELT PARAMETERS


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采用传统的高温熔融工艺制备了铒镱共掺铅硅酸盐玻璃. 测量了样品的吸收光谱、荧光光谱和折射率, 利用McCumber 理论和Judd-Ofelt 理论计算了该玻璃系统中Er3+离子4I13/2→4I15/2 能级跃迁受激发射截面和荧 光寿命.该玻璃在1 536 nm 处受激发射截面σemi 为8.62×10-21 cm2;荧光寿命长达11.32 ms(实验测量值为9.26 ms);在1536 nm 附近有很强的荧光发射,荧光有效线宽为46.5 nm;样品存在中心波长为580 nm 的4S3/2→4I15/2 跃迁的上转换荧光. 结果表明,该样品荧光寿命长,受激发射截面大,同时具有较弱的上转换发光等特性, 是制作高能脉冲光纤激光器的理想材料

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目前,国内外对于铕和铽等稀土配合物的可见区发光和应用都有大量研究,但对具有近红外发光(800-1700 nm)性能的稀土配合物的研究还处于起步阶段。由于稀土的近红外发光在光纤通讯、激光系统及诊断学等方面应用具有特殊的优点,越来越引起人们的兴趣和重视。 稀土近红外发光配合物的致命弱点是其光、热和化学稳定性较差,从而限制了其在很多领域的实际应用。而溶胶-凝胶材料和介孔材料具有良好的光、热和化学稳定性,能改善客体分子的结构环境和化学微环境,从而能有效提高客体分子的发光性能。因此,本论文将具有优良近红外发光性能的稀土配合物分别与上述两种基质复合,从实验和理论研究稀土近红外发光杂化材料的性能和应用价值,制备出具有良好稳定性的高效稀土近红外发光杂化材料,以期为光纤通讯、激光等领域提供潜在的候选材料。围绕这一宗旨,开展了如下工作: 通过原位技术分别得到了掺杂和嫁接[Ln(dbm)3phen]化合物(Ln = Er, Nd, Yb)的杂化凝胶材料,Ln-D-P gel和Xerogel-Ln。通过对其近红外发光性能的研究,表明材料中配体能很好的保护稀土离子,并将能量有效的传递给稀土离子。采用Judd-Ofelt理论对所得部分材料进行了光谱分析,基于实验数据和理论分析表明其具有潜在的光放大和激光应用价值。 选择了两种含全氟化烷基链的β-二酮配体Hhfth和Htfnb,通过功能化的phen-Si配体,将三元配合物[Ln(hfth)3phen] (Ln = Er, Nd, Yb, Sm)和[Pr(tfnb)3phen]成功共价嫁接到介孔MCM-41和SBA-15杂化材料中,得到的衍生材料Ln(hfth)3phen–MCM-41、Pr(tfnb)3phen–MCM-41和Ln(hfth)3phen–SBA-15、Pr(tfnb)3phen–SBA-15都保持了高度有序的介孔p6mm结构,并展现出稀土离子特征的近红外发射。所得稀土配合物功能化的材料的发射光谱能完全覆盖对光通讯极具应用价值的1300-1600nm区域。 通过对Er(dbm)3phen–M41(X, Y) (X = 1~14, Y = 3, 6, 12, 18, 24 h)材料系统的比较研究,选择了X = 12, Y = 6作为合成目标材料的优化参数,通过功能化的phen-Si配体将[Ln(dbm)3phen]配合物共价嫁接于有序介孔MCM-41和SBA-15中(Ln = Er, Nd, Yb),所得两类材料Ln(dbm)3phenM41和Ln(dbm)3phenS15都保持了很好的介孔有序性,并具有良好的近红外发光性能。通过对Ln(dbm)3phenM41和Ln(dbm)3phenS15两类材料发光行为的比较,以及两类材料中稀土离子的含量及孔结构的分析,推出以SBA-15为载体得到的材料在相对发光强度和荧光寿命上,均比以MCM-41为载体的材料有所提高。 通过对8-羟基喹啉配体进行改性,合成了具有双功能的配体Q-Si,继而合成了共价嫁接8-羟基喹啉衍生物的介孔杂化材料Q–SBA-15,其形貌均一,并具有高度有序的介孔p6mm结构。通过配体交换反应,得到了嫁接稀土喹啉配合物的具有近红外发光性能的介孔杂化材料LnQ3–SBA-15 (Ln = Er, Nd, Yb),其仍然保持高度有序的介孔结构,且外形呈现与母体材料Q–SBA-15相似的弯曲圆柱状。激发配体的吸收,LnQ3–SBA-15材料都分别展现出相应稀土离子特征的近红外发射,并详细分析和讨论了所得介孔杂化材料的近红外发光性能。

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稀土配合物的发光具有发射带窄、色纯度高、峰发光位置不受配体环境变化的影响、发光不受温度影响等特点,而且发射峰覆盖400-1800纳米的可见区和近红外区,因此可以作为有机电致发光器件的发光层材料。现在的研究大多集中于铕、铽配合物的电致发光器件研究,对于近红外稀土配合物的电致发光以及发白光的镝配合物研究相对较少,但是近红外发光的稀土铒、钕、镱在光通讯、激光技术、生物医学、荧光探针等方面具有特殊的应用前景。在本论文中主要阐述了新型稀土配合物的设计与合成、在器件方面的应用以及器件结构机理的研究。 在本论文中,我们主要研究吡唑酮的衍生物配体对于稀土离子的敏化激发作用。通过配体基团的改性,得到发光更有效的新型稀土配合物。首先,合成了配体PM,并选择TP、Phen、Bipy、Bath做第二配体制备镝、铒、钕、镱、钐等的配合物。解析了配合物的晶体结构,测试得到了各种配合物的光致发光性能,系统分析了几种配合物中配体到中心稀土离子的能量传递过程,研究了配体对稀土的敏化机制。其中镝配合物显示近白光的发射,色坐标为x=0.35,y=0.40,以此配合物为发光层的器件显示明亮的白光,最大发光亮度为527cd/m2,是目前已经报道的镝配合物器件中,性能最突出的一个。 设计合成了配体PT、PC、PF,利用TP和Bath做中性配体与镱离子形成配合物YbPT3Bath、YbPT3TP、YbPC3Bath,它们都显示977纳米的近红外发射。经过分析发现,配体对镱离子的敏化过程是通过电子转移的机制来完成的。通过几种镱配合物发光强度对比发现YbPT3Bath、YbPC3Bath的发射最强。首先将YbPT3Bath用于电致发光器件中,发现其具有较好的电子传输特性,而且YbPM3TP2具有较好的空穴传输特性。因此,我们将这两种配合物结合制备了双发光层电致发光器件,得到的器件比单发光层器件的性能提升了若干倍。我们认为,双发光层器件结构改善了载流子的传输和最终的复合,使得激子在发光层内形成,提高激子激发发光层材料的效率。最后,利用这种双发光层器件结构得到了辐照度比较理想的镱配合物近红外器件。 对ErPM3TP2、NdPM3TP2配合物的发光性能做了系统研究。首先,分析了它们的晶体结构,得到了具体的晶体参数和结构组成。二者在紫外区的吸收光谱都显示为配体的吸收,在紫外区之后出现了稀土离子的特征吸收峰,由此我们利用Judd-Ofelt理论分析计算了Er3+、Nd3+离子在这个配位环境中的振子强度参数,最后得到Er3+、Nd3+离子从激发态能级到下能级的电偶极跃迁辐射几率以及相应的自然寿命值。利用这两种配合物做为发光层材料制备了系列近红外电致发光器件,得到理想的辐照度强度,证明它们在制备近红外器件方面具有潜在应用价值。

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A series of Nd3+-doped LaF3 nanoparticles with Nd3+ concentrations from 0.5 to 10 mol% were synthesized. The fluorescence intensity and lifetime of the nanoparticles at various Nd3+ doping concentration were investigated. The nanoparticles displayed strongest fluorescence intensity at 3 mol% Nd3+ concentration. Eighty-eight percentage quantum efficiency was obtained when the Nd3+ concentration was 0.5 mol%. Optical properties of nanoparticles were studied according to Judd-Ofelt theory. A larger emission cross-section, sigma(em), for F-4(3/2) -> I-4(11/2) transition of the Nd3+ ion was obtained as 3.21 x 10(-20) cm(2), which was two times of the currently reported value. The larger emission cross-section and strong fluorescence intensity demonstrate that these nanoparticles are promising materials for laser applications. (C) 2010 Published by Elsevier B. V.

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The crystal structure of Er(PM)(3)(TP)(2) [PM = 1-Phenyl-3-methyl-4-isobutyryl-5-pyrazoloiie, TP = triphenyl phosphine oxide] was reported and its photoluminescence properties were studied by UV-vis absorption, excited, and emission spectra. The Judd-ofelt theory was introduced to calculate the radiative transition rate and the radiative decay time of 3.65 ms for the I-4(13/2) -> I-4(15/2) transition of Er3+ ion in this complex.

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in this communication, a novel Er3+ complex Er(PT)(3)TPPO [PT = 1-phenyl-3-methyl-4-tert-butylbenzoyl-5-pyrazolone, TPPO = triphenyl phosphine oxide] is successfully synthesized and characterized by elemental analysis and single-crystal X-ray diffraction. Its optical properties and the energy transfer process from the ligand PT to the Er3+ ion are investigated, the typical near-infrared (NIR) luminescence (centered at around 1530 nm) is attributed to the I-4(13/2) -> I-4(15/2) transition of Er3+ ion which results from the efficient energy transfer from PT to Er3+ ion (an antenna effect). The wider full width at half maximum (78 nm) peaked at 1530 nm in the emission spectrum and the Judd-Ofelt theory calculation on the radiative properties suggest that Er(PT)(3)TPPO should be a promising candidate for tunable lasers and planar optical amplifiers.

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A trivalent neodymium ion (Nd3+) complex Nd(PM)(3)(TP)(2) was synthesized, and its optical properties was studied by introducing Judd-Ofelt theory to calculate the radiative transition rate and the radiative decay time of the F-4(3/2) -> (4)l(J), transitions in this Nd(III) complex. The strong emissions of this complex at near-infrared region were owing to the efficient energy transfer from ligands to center metal ion. The potential application of this complex in NIR electroluminescence was studied by fabricating several devices. The maximum NIR irradiance was obtained as 2.1 mW/m(2) at 16.5 V.

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We report in this paper the spectral characteristics of Er3+ (2 at.%)-activated and Ce3+ (0.3 at.%)-sensitized yttrium aluminium garnet (YAG:Er,Ce) laser crystals grown by the Czochralski technique. The absorption and emission spectra were measured at room temperature. By using absorption spectra and Judd-Ofelt theory the experimental oscillator strengths of the Er3+ transitions in the YAG:Er,Ce crystals were calculated. The energy transfer between the Er3+ and Ce3+ ions is also discussed.

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掺钕钙铝磷酸盐玻璃的光谱参数于亚勤,张思远,王庆元,盛桂云(中国科学院长春应用化学研究所长春130022)(长春冶金专科学校长春)关键词掺钕钙铝磷酸盐玻璃,光谱参数,Judd-Ofelt理论1960年第一台红宝石激光器问世后,1961年便出现了掺钕钡...

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根据HoP_5O_(14)的吸收光谱和荧光光谱,用Judd-Ofelt理论计算了Ho~(3+)的强度参数.并计算了激发能级的辐射跃迁速率、辐射寿命、荧光分支比和积分发射截面等光谱参数.

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This work reports the structural and spectroscopy characterization of poly(styrene sulfonate) (PSS) films doped with neodymium (Nd) ions. Nd-PSS films were processed using the acid of poly(styrene sulfonate) - H-PSS and neodymium nitrate - Nd(NO(3))(3); the maximum incorporation of Nd ions in the polymeric matrix was equal 19.3%. The absorption in the UV-Vis-NIR spectral region presents typical electronic transitions of Nd 3, ions, with well resolved peaks. The infrared spectra present the transition bands of PSS with characteristic line shape broadening, and the presence of vibrational modes of N-O groups in the range of 1400-720 cm(-1), prove the permanence of Nd(NO(3))(x), with x = 1, 2 and/or 3. in the H-PSS matrix. UV-Vis site selective photoluminescence data indicate that the incorporation of Nd 31 introduces a blue shift in PSS emission (325-800 nm), decreasing the interaction between adjacent PSS lateral groups (aromatic rings). Nd(3+) reabsorption and energy transfer effects between the PSS matrix and Nd(3+) were also observed. The IR emission of Nd-PSS films at 1076 rim ((4)F(3/2) -> (4)I(11/2)) present constant efficiency, independent on Nd(3+) concentration. The Judd-Ofelt theory was employed to analyze radiative properties. The excitation spectra prove the energy transfer between the polymeric matrix and Nd(3+). Complex impedance data was used to probe relaxation processes during the charge transport within the polymeric matrix. (C) 2008 Elsevier B.V. All rights reserved.

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We investigate the linear optical properties and energy transfer processes in tungstate fluorophosphate glass doped with thulium (Tm3+) and neodymium (Nd3+) ions. The linear absorption spectra from 370 to 3000 nm were obtained. Transitions probabilities, radiative lifetimes, and transition branching ratios were determined using the Judd-Ofelt [Phys. Rev. 127, 750 (1962); J. Chem. Phys. 37, 511 (1962)] theory. Frequency up-conversion to the blue region and fluorescence in the infrared were observed upon pulsed excitation in the range of 630-700 nm. The excitation spectra of the luminescence were obtained to understand the origin of the signals. The temporal decay of the fluorescence was measured for different concentrations of the doping ions. Energy transfer rates among the Tm3+ and Nd3+ ions were also determined.

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Er3+ -containing gallium-lanthanum oxysulfide glasses have been prepared from Ga2O3 and La2S3 in a sulfur/argon reactive atmosphere. The samples have been characterized by absorption and emission spectroscopy and IR emission kinetics. Er3+ electronic transition intensities have been analyzed in the light of the Judd-Ofelt formalism, and quantum efficiencies evaluated for the Er3+ emission at 1.5 and 2.7 mum. The results so obtained suggest that these glasses display favorable properties concerning IR optical applications. (C) 2002 Elsevier B.V. B.V. All rights reserved.

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We synthesize and study the properties of praseodymium doped fluoroindate glasses. Glass compositions with praseodymium molar concentrations up to 5% were obtained with good optical quality. Thermal, optical, and luminescence properties are investigated. Judd-Ofelt analysis is used to determine radiative lifetime and emission cross-section of the orange transition originating from the 3P0 level. We find that these glasses are good candidates for the realization of blue diode laser pumped orange lasers for quantum information processing applications. © 2012 Elsevier B.V. All rights reserved.

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Pós-graduação em Ciência dos Materiais - FEIS