SiO2气凝胶薄膜中Eu3+离子的跃迁

利用溶胶－凝胶法制得了Ｅｕ＾２＋掺杂ＳｉＯ２气凝胶薄膜,并对其发光及跃迁性质进行了研究。使用原子力显微镜对样品的型貌结构做了观测、采用ＸＲＤ和ＩＯＲ对所得样品的结构进行了研究,测量了样品的激发一发光谱、吸收光谱和时间分辨光谱。通过Ｊｕｄｄ－Ｏｆｅｌｔ理论计算了Ｅｕ＾３＋的＾Ｄ０的辐射跃迁几率,并根据时间分辨光谱研究了＾５Ｄ１的无辐射跃迁几率及弛豫性质。虽然结果与掺Ｅｕ＾３＋的体硅玻璃没有很大差别,     

Eu3+离子作为荧光探针研究TiO2凝胶的结构变化

利用Ｅｕ＾３＋离子的＾５Ｄ０→＾７Ｆ２超灵敏跃对环境的极度敏感性,将Ｅｕ＾３＋离子引入溶胶－凝胶法制备的ＴｉＯ２凝胶玻璃中,并对Ｅｕ＾３＋离子掺入后的光谱性质进行了研究,从而表征了ＴｉＯ２凝胶形成中的结构变化过程。结果发现,随处理温度的升高,＾５Ｄ０→＾７Ｆ２跃迁强度逐渐增强,说明水分子的不断挥发、缩聚反应进行的不断完全;同时将Ａｌ＾３＋离子掺入到溶胶中,研究了其在Ｅｕ＾３＋离了的聚集所导致的荧光     

高温高压合成的硅酸锶有铕铋的发光特性

用高温高压方法合成了Ｓｒ２ＳｉＯ４Ｅ＾３＋ｕ，Ｂｉ＾３＋和ＳｒＳｉＯ３Ｅｕ＾３＋＿，Ｂｉ＾３＋，研究了合成压力对其发光性能的影响，与用溶胶－凝胶共沉淀法和常压高温法合成的产品作比较，常压制备的ＳｒＳｉＯ３Ｅｕ＾３＋，Ｂｉ＾３＋为六角结构，而在２．３４－４．１０ＧＰａ的合成压力范围内，它转变为赝正交结构；常压下Ｓｒ２ＳｉＯ４；Ｅｕ＾３＋，Ｂｉ＾３＋，为单斜结构，在４．２ＧＰａ的合成压力下，未发现其结     

一种新型有机—无机复合发光材料

通过差热－热失重，红外光谱和紫外光谱等测试手段，对溶液中合成的吡啶－２－羧酸：Ｅｕ＾３＋配合物进行了表征，并且通过原位合成方法在ＳｉＯ２凝胶中合成了吡啶－２－羧酸：Ｅｕ＾３＋配合物。     

用溶胶—凝胶法制备的Y2SiO5：Gd,Eu荧光粉的发光性能

用溶胶－凝胶法合成了Ｙ２ＳｉＯ５：Ｇｄ,Ｅｕ红色荧光粉。探讨了烧结工艺对粉体的结构及发光性能的影响。首次报道了搀杂Ｇｄ的Ｙ２ＳｉＯ５：Ｅｕ红色荧光粉的发光性能。研究结果表明,搀杂适当浓度的Ｇｄ,可以显著提高ＹｓＳｉＯ５：Ｅｕ红色荧光粉的发光强度,在Ｙ２ＳｉＯ５基质中,Ｇｄ＾３＋是Ｅｕ＾３＋的优良敏化剂。     

（Y,Zn,Sr）3（P,VO4）：Eu^3＋,Bi^3＋发光性质的研究

合成了组成为（Ｙ，Ｚｎ，Ｓｒ）３（Ｐ，ＶＯ４）：Ｅｕ＾３＋，Ｂｉ＾３＋的荧光材料，经Ｘ射线结构分析确定为Ｚｎ３（ＰＯ４）２结构，属于单斜晶系，空间群为Ｐ２１／ｎ。讨论了基质组成对Ｅｕ＾３＋离子发光性质的影响，用Ｙ＾３＋取代了一部分Ｚｎ＾２＋；用ＶＯ４取代了一部分ＰＯ４由于基质的４３６ｎｍ发射与Ｅｕ＾３＋的激发态能级的能量重叠，Ｅｕ＾３＋产生较强的５９８ｎｍ和６１８ｎｍ发射。另外，掺入少量Ｂｉ＾３＋     

BaFCl：Eu^2＋,Eu^3＋的光激励发光过程

本文首次报道了ＢａＦＣｌ：Ｅｕ＾２＋,Ｅｕ＾３＋的光激励发光。实验结果发现,在ＢａＦＣｌ：Ｅｕ中Ｅｕ＾３＋对Ｅｕ＾２＋的光激励发光有增强作用。在ＢａＦＣｌ：Ｅｕ的光致发射光谱中同时观察到对Ｅｕ＾２＋、Ｅｕ＾３＋及基质的本征发射,而光激励发射光谱中只观察到Ｅｕ＾２＋的发射,表明光致发光与光激励发光存在着很大的差异。这些结果表明,发光中心Ｅｕ＾２＋、Ｅｕ＾３＋及基质之间存在着相互作用和能量传递。本文提     

P2O3—B2O3—Al2O3—SrO—BaO玻璃中的Yb^3＋非辐射能量转移下E …

本文研究了共掺Ｅｒ＾３＋／Ｙｂ＾３Ｐ２Ｏ３－Ｂ２Ｏ３－Ａｌ２Ｏ３－ＳｒＯ－ＢａＯ玻璃的能量转移过程。实验中制备了高掺杂Ｂｂ＾３＋离子的双掺Ｅｒ＾＃＋／Ｙｂ＆＾３＋的磷酸盐玻璃样品。在Ｅｒ＾３＋／Ｙｂ＾３＋掺杂比率〉１：１８（ｍｏｌ％）时,观测到了基于Ｙｂ＾３＋离子至Ｅｒ＾３＋离子能量转移下Ｅｒ＾３＋（＾３Ｉ１３／２→＾４Ｉ１５／２）的增强发射和ｂ＾３＋（＾２Ｆ７１／→＾２Ｆ５／２）发射的减弱,当Ｂ     

SiO2凝胶玻璃中Eu^＋,Tb^3＋与1,10—邻菲罗啉配合物的原位化学？…

应用原位化学复合方法，将Ｅｕ＾３＋、Ｔｂ＾３＋与，１，１０－邻菲罗啉配合光学均匀复合到ＳｉＯ２凝胶玻璃中，解决了国稀土含氮配合物易水解而难以用溶胶－凝胶工艺将其均匀掺入无机基质的问题。研究了原位配合物的荧光和热学性能。结果表明，由于配合物的形成使稀土离子特征荧光强度显著增加，而无机基质的保护作用则使原位配合物热稳性提高２００℃以上。化学合成纯配合物Ｅｕ（Ｐｈｅｎ）２Ｃｌ３·２Ｈ２Ｏ的高分辨荧光谱表     

氟化物中Eu^2＋,Ce^3＋的浓度猝灭及其机理

本文详细地研究了ＢａＹＦ５和ＫＣａＦ３基质中Ｅｕ＾２＋、Ｃｅ＾３＋浓度对其发光的影响，发现两基质中Ｅｕ＾２＋、Ｃｅ＾３＋的猝灭浓度都较低；提出了Ｅｕ＾２＋、Ｃｅ＾３＋的浓度猝灭机理，计算了猝灭浓度和临界距离，并与实验结果进行了比较。     

Characteristics of plasma hydrogenated ZnO films oriented along the (11-20) plane grown by pulsed laser deposition

Single crystalline phase ZnO layers oriented along the (11-20) plane were successfully grown on (1-102) sapphire substrate by using a modified two-step pulsed laser deposition process. The full width at half maximum of rocking curve for (11-20) ZnO was 430 arc sec. After a hydrogen plasma treatment, the value of surface roughness was decreased from 37.5 to 10.2 nm. And the intensity of ultra-violet emission at 380 nm in cathodoluminescence (CL) spectrum was greatly increased by the hydrogen plasma irradiation. In the time-resolved photoluminescence (TRPL) spectra, the minimum value of decay time was 36 ps after the hydrogen plasma irradiation for 5 min. Especially, CL and TRPL results show the potential of high efficient optoelectronic devices by using the hydrogen plasma treatment.     

Cr-Tm ion pairs in Gd3Ga5O12 garnet

A study is presented about Cr³⁺→Tm³⁺ energy transfers in Gd₃Ga₅O₁₂ garnet at 10 K. By time-resolved spectroscopy and analysis of decay kinetics we determine the nature of the interaction and we show the existence of chromium-thulium pairs in which the chromium emission wavelength is shifted from 693.6 to 694 nm.     

SiO2气凝胶薄膜中Eu3+离子的跃迁

利用溶胶-凝胶法制得了Eu3+掺杂SiO2气凝胶薄膜,并对其发光及跃迁性质进行了研究.使用原子力显微镜对样品的型貌结构做了观测,采用XRD和IR对所得样品的结构进行了研究,测量了样品的激发—发射光谱、吸收光谱和时间分辨光谱.通过Judd--Ofelt理论计算了Eu3+的5D0的辐射跃迁几率,并根据时间分辨光谱研究了5D1的无辐射跃迁几率及弛豫性质.虽然结果与掺Eu3+的体硅玻璃没有很大差别,但可通过此简易低温的方法制得掺稀土离子的良好薄膜,这对得到具有轻质玻璃性质的发光薄膜展示了广阔应用前景.     

Fast-gated intensified charge-coupled device camera to record time-resolved fluorescence spectra of tryptophan

The possibilities of a 200 ps gated intensified charge-coupled device (CCD) camera to record time-resolved fluorescence were explored using the fluorescing amino acid tryptophan and its derivative Nacetyl-tryptophan amide (NATA) as model compounds. The results were compared to complementary data from time-correlated single-photon counting (TCSPC) experiments. If a spectral resolution of 1-2 nm is desired, the fast-gated intensified CCD (ICCD) camera is the method of choice. For a 10(-5) M tryptophan solution, time-resolved emission spectra and intensity decays (measured over 12 ns at 25 ps resolution) could be obtained in typically 10 minutes, giving the well-known lifetimes of 0.5 and 3 ns. In addition, a longer lifetime of 7 ns was found at the red edge of the spectrum. The very short gate time of the ICCD camera allowed us to observe a shift in the emission maximum of tryptophan even within the first nanosecond of decay of the fluorescence emission. As expected from the tryptophan rotamer model, such a shift is not observed in NATA. Using amplitudes obtained by global analysis, decay-associated spectra of these lifetimes were constructed.     

One-step synthesis and luminescent properties of nanocrystalline YVO4:Eu3+ powders

In this paper, nanocrystalline YVO4:Eu3+ powders have been successfully synthesized via high-temperature solution-phase synthesis process. The nanocrystalline YVO4:Eu3+ particles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV/Nis absorption spectra and luminescence spectra, luminescence decay curve and Fourier transform infrared (FT-IR), X-ray photoelectron spectra (XPS) respectively. The as-prepared nanocrystalline YVO4:Eu3+ particles are well crystallized with ellipsoidal morphology. The emission of YVO4:Eu3+ particles show emission originating from the 5D0 level, with 5D0-7F2 at 616 nm as the most prominent group. The excitation spectrum fits basically with the absorption spectrum from the vanadate ions. FT-IR and XPS spectra indicate that the surface ligands of nanocrystalline particles were oleic acid and oleylamine. The lifetime for the luminescence of Eu3+ in the as-prepared YVO4:Eu3+ samples are shorter than that of the bulk material due to the absorption of organic ligands on the nanoparticle surface.     

Multispectral fluorescence lifetime imaging of feces-contaminated apples by time-resolved laser-induced fluorescence imaging system with tunable excitation wavelengths

We recently developed a time-resolved multispectral laser-induced fluorescence (LIF) imaging system capable of tunable wavelengths in the visible region for sample excitation and nanosecond-scale characterizations of fluorescence responses (lifetime imaging). Time-dependent fluorescence decay characteristics and fluorescence lifetime imaging of apples artificially contaminated with a range of diluted cow feces were investigated at 670 and 685 nm emission bands obtained by 418, 530, and 630 nm excitations. The results demonstrated that a 670 nm emission with a 418 nm excitation provided the greatest difference in time-dependent fluorescence responses between the apples and feces-treated spots. The versatilities of the time-resolved LIF imaging system, including fluorescence lifetime imaging of a relatively large biological object in a multispectral excitation-emission wavelength domain, were demonstrated.     

Large array of single, site-controlled InAs quantum dots fabricated by UV-nanoimprint lithography and molecular beam epitaxy

We present the growth of single, site-controlled InAs quantum dots on GaAs templates using UV-nanoimprint lithography and molecular beam epitaxy. A large quantum dot array with a period of 1.5 μm was achieved. Single quantum dots were studied by steady-state and time-resolved micro-photoluminescence experiments. We obtained single exciton emission with a linewidth of 45 μeV. In time-resolved experiments, we observed decay times of about 670 ps. Our results underline the potential of nanoimprint lithography and molecular beam epitaxy to create large-scale, single quantum dot arrays.     

Luminescent properties of La3PO7:Eu3+ nanoparticles

La3PO7:Eu3+ samples were prepared by combustion and annealing and characterized by X-ray diffraction and transmission electron microscopy. It was found that the average size of the particles is about 80 nm. The red emission from the 5D0 --> 7F2 transition of the Eu3+ ions under ultraviolet light excitation is much stronger than the orange emission from the 5D0 --> 7F1 transition. The emission spectra, charge transfer band, laser selective excitation spectra, and time-resolved spectra indicate that symmetry of the local environment of Eu3+ lacks an inversion center and Eu3+ ions occupy at least two types of sites in the La3PO7 crystal. The superior color chromaticity compared to other phosphates and borates doped with Eu3+ means La3PO7:Eu3+ may have potential as a luminescent material.     

Picosecond time-resolved bleaching dynamics of self-assembled quantum dots

Picosecond bleaching dynamics of vertically stacked self-assembled quantum dots (QDs) is investigated by means of time-resolved pump-probe differential reflection spectroscopy (TRDR) at room temperature (RT). We observe that the absorption spectrum, which represents the QD density of states at RT, is strongly shifted with respect to the photoluminescence spectrum. This shift can not be interpreted by carrier emission and re-trapping alone. TRDR allows us to study the dynamics of the pump generated carriers within the QDs. From the time-resolved measurements, we detect that the bleaching decay time has a strong energy dependence and is dominated by radiative and nonradiative recombination at low energy and by carrier emission at high energy.