Eu3+掺杂铌酸盐玻璃的光谱性质

研究了Eu^3 掺杂铌磷与铌硅系列玻璃的发射光谱，声子边带谱及^5D0能级寿命，计算了样品的强度参数。随着Nb2O5浓度的增加，Eu-O键强增大，共价性增强，Eu^3 的局域环境对称性降低，电－声子耦合增强，^5D0能级的无辐射过程加快，寿命变短，温度猝灭加剧。研究了从77－690K铌磷与铌硅系列玻璃中Eu^3 离子在488nm激光激发下的变温荧光发射特性，求出了温度猝灭速率。分析了发光强度增强与减弱的原因，即热布居与无辐射过程随温度的变化关系，研究了谱线宽度与峰值位置随温度的变化关系。     

GdNbO_4∶Er~(3+)/Yb~(3+)荧光粉的上转换发光与温度特性

采用传统高温固相法制备了GdNbO_4∶10%Yb~(3+),x%Er~(3+)荧光粉。利用XRD对样品的晶体结构进行了分析,结果表明所得的样品为纯相。在980nm光纤激光器激发下,测量了样品的上转换发射光谱,实验发现样品发生了浓度猝灭。利用荧光强度比(FIR)方法研究了GdNbO_4∶Yb~(3+)/Er~(3+)荧光粉的温度传感特性,结果表明灵敏度随温度的升高先增大后减小。建立了Er~(3+)的两个绿色发射能级的温度猝灭物理模型并用其成功解释了样品的绿色上转换发光温度猝灭现象。     

变温下Y2O3∶Eu3+纳米晶的荧光光谱和动力学过程

通过分析影响Y2O3:Eu3+在488nm激光激发下的5D0→7F2变温荧光发射强度的因素,建立起公式并对实验数据进行拟合,得到纳米晶的温度猝灭速率大于体材料的温度猝灭速率.测得Y2O3:Eu3+纳米晶和体材料的5D0→7F2发射峰的变温线宽,通过内应力和量子限域效应对其不同进行了解释.测量了Y2O3:Eu3+在共振激发下的5D0能级的荧光衰减时间随温度的变化,又利用公式对其进行拟合,得出了相比于体材料,纳米晶的辐射跃迁速率和无辐射跃迁速率均增大,但量子效率变小的结论.然后利用晶格畸变和表面态效应对上述结 关键词： 温度猝灭 Y2O3:Eu3+纳米晶 荧光衰减 线宽     

变温下Y2O3∶Eu3+纳米晶的荧光光谱和动力学过程

通过分析影响Y2O3: Eu3+在488nm激光激发下的5D0→7F2变温荧光发射强度的因素,建立起公式并对实验数据进行拟合,得到纳米晶的温度猝灭速率大于体材料的温度猝灭速率.测得Y2O3: Eu3+纳米晶和体材料的5D0→7F2发射峰的变温线宽,通过内应力和量子限域效应对其不同进行了解释.测量了Y2O3: Eu3+在共振激发下的5D0能级的荧光衰减时间随温度的变化,又利用公式对其进行拟合,得出了相比于体材料,纳米晶的辐射跃迁速率和无辐射跃迁速率均增大,但量子效率变小的结论.然后利用晶格畸变和表面态效应对上述结论进行了解释.     

荧光发射强度影响因素及荧光猝灭实验研究

荧光发射强度在荧光显微术科学观测中至关重要。理论分析了三大影响荧光发射强度的重要因素:分子吸收激发光光子的能力、荧光量子产量及其荧光饱和与荧光猝灭,指出选择具有大光吸收截面和高量子产量的荧光分子,能有效保证荧光发射强度;确定合理的激发光强度范围,可避免不必要的荧光饱和现象。进一步实验研究了超高真空和大气环境下的荧光猝灭现象,得出超高真空时荧光分子的荧光猝灭现象极不明显,而大气环境可造成荧光光强指数递减的结论。     

铅离子对碳纳米颗粒荧光发射规律的影响

以热解石墨为原料,利用电化学方法,制备了荧光碳纳米颗粒。系统地研究了在不同浓度、时间、pH值、温度等条件下,Pb2+离子对碳纳米颗粒荧光发射规律的影响。实验结果表明:Pb2+离子不改变光谱形状,但可以降低荧光峰值强度;Pb2+离子作用荧光碳纳米颗粒的时间越长,猝灭效率越低;pH值不同,猝灭效率不同;随着温度的升高,Pb2+离子对碳纳米颗粒荧光的猝灭效率逐步提高。其猝灭机理可能为电荷转移猝灭和动态猝灭。     

纳米晶ZrO_2∶Dy~(3 )的光致发光和能量传递性质

研究了Dy3 离子掺杂的ZrO2纳米粉体的光致发光性质。观测到Dy3 离子的室温强特征发射和浓度猝灭现象以及基质ZrO2与Dy3 离子之间的能量传递过程。发现了煅烧温度对样品的晶相有明显的影响,随着煅烧温度的变化,晶相也随之改变。晶相的改变使样品的荧光发射产生较大的差异,并观测到两个发射中心。通过对荧光强度与激活离子Dy3 离子浓度的关系研究发现,Dy3 离子在纳米ZrO2基质中存在浓度猝灭现象,最佳掺杂浓度取决于ZrO2基质的晶相,不同晶相导致不同的猝灭浓度,当基质晶相表现为四方相时,猝灭浓度为0.5%,而基质晶相为混合相时,猝灭浓度为1%。能量传递也依赖于样品的晶相。当煅烧温度为950℃时能量传递效果最好,并且从微观结构上给出了解释基质与Dy3 离子之间的能量传递的模型。     

胶乳微球与抗体蛋白相互作用机理的荧光光谱法分析

利用共价偶联的方法制备了胶乳-抗体蛋白复合物,并采用荧光光谱法对复合物的性质进行了研究,以揭示胶乳微球与抗体蛋白之间的相互作用机理。内源荧光光谱分析结果表明,共价偶联后,抗体蛋白的最大发射峰发生显著蓝移,最大发射峰强度显著降低,抗体蛋白的三级结构发生了一定的变化,胶乳微球与抗体蛋白之间的相互作用对抗体蛋白的内源荧光有显著的猝灭作用,猝灭效果随着偶联体系pH值以及胶乳浓度的增加而增强,猝灭机制为静态猝灭。外源荧光光谱分析结果表明,共价偶联后抗体蛋白的最大发射峰强度显著增强,且随着偶联体系pH值的升高,抗体蛋白的疏水性显著降低,随着胶乳浓度的增加,疏水性逐渐升高。     

含Eu3+离子的Na2O-K2 O-SiO2-Al2O3系统玻璃的制备及其变温发射光谱与结构特性

通过高温熔融法制备了含Eu^3 离子的Na2O-K2O-SiO2-Al2O3系统玻璃。在488nm波长光的激发下，系统地研究了上述玻璃从77K到700K温度范围的变温发光特征。发现总的荧光强度首先随温度的升高而大幅度升高，然后随温度的升高而减少，用声子辅助吸收与热激活过程及温度淬灭效应定性地解释了上述强度的变化，同时测量与分析了Eu^3 离子的晶格场参量。结果表明，Eu^3 离子与氧离子的距离随着温度升高而变短，而Eu^3 离子的配位数不随温度而变化。     

苯酚磺酞类酸性染料与人血清白蛋白的结合

在人体条件下 ,用荧光光谱法研究了苯酚磺酞类酸性染料苯酚红、甲酚红、氯酚红、溴甲酚紫、间甲酚紫与人血清白蛋白 (HSA)之间的相互作用。实验表明 :苯酚磺酞类酸性染料对人血清白蛋白的荧光有较强的猝灭作用 ,其荧光猝灭主要为静态猝灭 ,从荧光猝灭结果求得不同温度下各染料与HSA的结合常数K ,发现染料取代基的引入使K值增大 ,且随反应温度上升K值下降。由染料与HSA反应焓变、熵变 ,确定染料与HSA的结合主要是静电引力。依据非辐射能量转移机理 ,探讨了不同温度下该类染料与HSA相互结合时 ,其给体 受体间距离和能量转移效率。进一步证实了该类反应为单一静态猝灭过程 ,且阐明了其猝灭机理是通过能量转移产生的。     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.