激光诱导荧光光谱分析法研究(Ⅸ)Dy-AA-TOPO-SLS的发光机理及分析应用

本文采用自己组装的激光诱导荧光光谱测定装置,研究了镝-乙酰丙酮-三正辛基膦化氧(Dy-AA-TOPO)体系在表面活性剂十二烷基磺酸钠(SLS)存在时的吸收光谱特性和激光诱导发光光谱特性,首次在室温测得AA的磷光发射.并从配体、中心离子的化学性质和所形成配合物的对称性及它们的光谱能级等方面综合考虑,提出配合物体系的发光机理和荧光发射过程中的能量传递方式.共存离子对配合物体系荧光发射强度的影响表明,在一定浓度范围内,某些稀土和非稀土离子可产生荧光增强作用,即“协同发光”效应.拟定出测定痕量镝的激光诱导荧光分析方法,对于单个激光脉冲产生的荧光,镝的工作曲线的线性范围为1-200ppb.用于高纯氧化钇中痕量镝的测定,获得了满意的结果.     

协同发光效应及机理探讨

在研究共存离子对稀土配合物荧光强度影响时发现,许多稀土和非稀土离子在一定浓度范围内可对配合物的荧光产生增强效应.这种现象与协同萃取类似,我们将其命名为“协同发光效应”.本文采用激光诱导荧光光谱法,研究了十四种稀土离子对Eu、Sm-TTA-Phen-Triton X-100体系和Eu、Sm-DBM-CPB体系的协同发光效应.并从稀土离子的化学性质,光谱能级和所形成配合物的化学结构和空间结构等方面综合考虑,提出协同发光机理.拟定出用于痕量铕和钐测定的薪的超高灵敏度分析方法.     

二苯甲酰基甲烷2,2''-联吡啶混合稀土配合物中钆、钇对铕发光的影响

在乙醇溶液中合成了以二苯甲酰基甲烷(DBM)和2,2'联吡啶(Dipy)为配体,三价铕、等摩尔三价铕-钆及等摩尔三价铕-钇混合稀土为中心体的配合物.测定了配合物的组成,研究了其红外光谱和荧光光谱.结果表明:配合物的最佳激发波长为425nm;在425nm波长光激发下,配合物发出较强的荧光;不发光的Gd3+和Y3+离子对Eu3+离子的发光有一定增强作用,其中钇使铕的荧光发射增强大于钆;这两个不发光稀土离子对铕的发射峰位影响不大.     

以铽离子为荧光探针测定尿样中痕量环丙氟哌酸

详细研究了环丙氟哌酸同稀土离子铽形成的配合物体系的荧光光谱特性及实验条件对荧光强度的影响。在pH为6．0的条件下,配合物荧光体系可发射铽离子强的特征荧光,其最大激发和发射波长为328和545nm。以稀土离子铽为荧光探针,测定尿样中痕量的环丙氟派酸可获得满意结果。     

铽-聚N-乙烯基乙酰胺体系中镧钆掺杂稀土配合物谱学研究

在乙醇溶液中合成了掺杂镧和钆的铽-聚N-乙烯基乙酰胺(PNVA)的掺杂稀土配合物, 并通过红外光谱、紫外光谱、 XPS光电子能谱和荧光光谱研究了该配合物的光谱性质. 结果表明: 掺杂稀土配合物中的稀土离子都与高分子配体PNVA产生配位作用. 配合物的最佳激发波长为303 nm;在此波长激发下, 配合物发出较强铽的特征荧光, 说明非荧光稀土离子(La3 和Gd3 )对Tb3 离子的发光有显著的增强作用, 而对Tb3 的发射峰位影响不大.     

稀土配合物的时间分辨荧光光谱法研究(Ⅱ)——Eu,Sm-DBM-TOPO体系的荧光衰减动力学特性和激光诱导时间分辨荧光光谱

本文以Nd:YAG泵浦的染料激光器为激发光源,门控光学多道分析仪为检测器,自制的触发器和荧光盒组装成一台激光诱导时间分辨光谱装置。采用此装置研究了在表面活性剂Triton X-100存在下铕、钐-二苯甲酰甲烷-三正辛基氧化膦(Eu、Sm-DBM-TOPO)体系的激光诱导发光光谱特性和荧光衰减动力学特性。讨论了荧光发射过程中的能量传递机制。拟定出测定痕有铕和钐的时间分辨光谱方法,用于高纯稀土氧化物等样品中痕量铕和钐的测定,结果满意。     

稀土配合物的时间分辨荧光光谱法研究(Ⅱ)——Eu,Sm-DBM-TOPO体系的荧光衰减动力学特性和激光诱导时间分辨荧光光谱

本文以Nd:YAG泵浦的染料激光器为激发光源,门控光学多道分析仪为检测器,自制的触发器和荧光盒组装成一台激光诱导时间分辨光谱装置。采用此装置研究了在表面活性剂Triton X-100存在下铕、钐-二苯甲酰甲烷-三正辛基氧化膦(Eu、Sm-DBM-TOPO)体系的激光诱导发光光谱特性和荧光衰减动力学特性。讨论了荧光发射过程中的能量传递机制。拟定出测定痕有铕和钐的时间分辨光谱方法,用于高纯稀土氧化物等样品中痕量铕和钐的测定,结果满意。     

苯甲酸含氮杂环镝配合物的合成、表征及发光性质

合成了以稀土镝为中心离子,以苯甲酸、卤代苯甲酸及邻菲啰啉和2,2'-联吡啶为配体的五种固态配合物。对配合物进行了稀土络合滴定,C、H和N的元素分析、紫外光谱、红外光谱和荧光光谱测定,推测其组成分别为Dy (BA)₃(bpy)、Dy (BA)_3(phen)、Dy(ClBA)₃(phen)(EtOH)、Dy(BrBA)₃(phen)(EtOH)和Dy(IBA)₃(phen)(EtOH)(BA=苯甲酸根,bpy=2,2'-联吡啶,phen=邻菲啰啉,ClBA=对氯苯甲酸,BrBA=对溴苯甲酸,IBA=对碘苯甲酸);苯甲酸羧基氧、邻菲啰啉和2,2'-联吡啶的氮原子与镝离子配位。配合物都具有较强的荧光,卤代苯甲酸配合物呈现规律发光,对氯苯甲酸-邻菲啰啉-镝配合物的发光效果较其它两种配合物强,对溴苯甲酸配合物又强于对碘苯甲酸配合物;苯甲酸-邻菲啰啉-镝配合物荧光强于苯甲酸-2,2'-联吡啶-镝配合物。     

二苯甲酰基甲烷2,2′-联吡啶混合稀土配合物中钆、钇对铕发光的影响

在乙醇溶液中合成了以二苯甲酰基甲烷 (DBM )和 2 ,2′联吡啶 (Dipy)为配体 ,三价铕、等摩尔三价铕 钆及等摩尔三价铕 钇混合稀土为中心体的配合物。测定了配合物的组成 ,研究了其红外光谱和荧光光谱。结果表明 :配合物的最佳激发波长为 4 2 5nm ;在 4 2 5nm波长光激发下 ,配合物发出较强的荧光 ;不发光的Gd3 + 和Y3 + 离子对Eu3 + 离子的发光有一定增强作用 ,其中钇使铕的荧光发射增强大于钆 ;这两个不发光稀土离子对铕的发射峰位影响不大     

对氯苯甲酸-2,4,6-三吡啶基三嗪稀土配合物的合成、表征及发光性能

以对氯苯甲酸为第一配体,2,4,6-三吡啶基三嗪(TPTZ)为第二配体,分别以铕、铽和镝为中心,合成了10种稀土配合物,并进行了元素分析、稀土络合滴定、等离子光谱、紫外光谱、红外光谱和发光光谱测定。配合物的组成为:RE(p-ClBA)3(TPTZ).2H2O和RE0.5Ln0.5(p-ClBA)3(TPTZ).2H2O(RE=Eu3+,Tb3,+Dy3+;Ln=La3,+Gd3,+Y3;+p-ClBA=对氯苯甲酸根;TPTZ=2,4,6-三吡啶基三嗪),均为非电解质;对氯苯甲酸的羧基氧原子与稀土离子配位,2,4,6-三吡啶基三嗪以主配位点上的3个氮原子与稀土离子配位;铕配合物的发光强度大于铽配合物的,镝配合物发光最弱;在上述3种发光稀土配合物中分别掺入发光惰性稀土离子镧、钆及钇后,发光强度有不同改变,掺入镧可明显增强铕、铽的发光强度,钆可敏化铕、铽和镝的发光,而钇的敏化作用较弱。表明:掺杂配合物并不完全是两种简单配合物的机械混合,而是有混配配合物生成。     

Two-photon spectroscopy of Hg2Cl2 crystals

Two-photon absorption of Hg₂Cl₂ crystals was investigated using a pulsed dye laser at T ω 8.5 K. Both the indirect method of monitoring the luminescence produced by two-photon absorption and the two-photon attenuation measurements of the laser beam were used. The excitation spectrum of the ∼ 3.13 eV (396 nm) luminescence was measured in the energy range 4.0 ⩽ 2hv ⩽ 5.5 eV. A strong maximum at 2hv ω 5.13 eV dominates the spectrum. Comparison with previous one-photon absorption data allows us to assign the parity of electronic states involved in the transitions. The band gap of Hg₂Cl₂ is found to be direct allowed.     

Pyrene-Naftylamide Bifluorophore for Spectra-Converting Media

New bifluorophore containing pyrene as an excitation energy donor and naphtylamide as an acceptor is synthesized and its optical properties are studied. It is founded that excitation spectrum of the bifluorophore is almost the sum of its constituents—pyrene and naftylamide. At the same time, in the luminescence spectrum there only the peak of acceptor luminescence is observed, which indicates the effective radiationless energy transfer from the donor to the acceptor. This is also proved by time resolved measurements of bifluorophore decay. The decay rate was calculated from decay curve and appear to be 0.25 нс^?1. The same value obtained from the Förster’s theory is almost by an order as high. It indicates that Förster’s does not applicable in this particular case. Instead, we have to use the electron excitation density functions approach.     

Use of short-wavelength synchrotron radiation to measure luminescence quantum yield and the luminescence excitation spectrum of polymers

We describe an optical diagnostics module and the instrumental and methodological features of ultrahigh vacuum experiments investigating the optical characteristics of condensed media in the short-wavelength (hv ~ 3.5–25 eV) range of the spectrum of probing synchrotron radiation. We give a brief presentation of the results of an experimental determination of the spectral dependence of the luminescence quantum yield and the luminescence excitation spectrum of ablatable polymer dielectrics on the Kurchatov synchrotron radiation source at values of the probing radiation power density (I ₀ ~ 10¹² photons/cm²∙sec) that are below threshold for extended surface vaporization and a surface temperature of the condensed targets equal to 77–300 K.     

Stark splitting and energy transfer between Dy3+-Ho3+ and between Tb3+-Er3+ in calcium-lithium borate glass

Fluorescence spectrum of Dy³⁺, Dy³⁺-Ho³⁺, Tb³⁺ and Tb³⁺-Er³⁺ doped in calibo glass have been studied using Ar⁺ and excimer lasers. Non-radiative energy transfer from trivalent dysprosium and terbium (donors) to holmium and erbium (acceptors) respectively has been observed on the basis of decrease in the life time of the levels and reduction in fluorescence intensity of Dy³⁺ and Tb³⁺ on increasing Ho and Er concentrations. The interaction mechanism of donor and acceptor ions is found to be dipole-dipole in both cases. Various parameters such as donor-acceptor distances, non-radiative energy transfer efficiency (η) and energy transfer probability (P _da) have been computed. Stark splitting have also been marked in several intense transition of the two.     

CdTe量子点与罗丹明B水溶液体系下的双光子激发荧光共振能量转移

采用时间分辨荧光光谱技术研究了在双光子激发下不同尺寸的量子点与罗丹明B 之间的荧光共振能量转移. 研究结果表明, 在800 nm的双光子激发条件下, 体系间能量转移效率随着供体吸收光谱与受体荧光光谱的光谱重叠程度增加而增加; 理论分析表明, 供体和受体间的Förster半径增加是导致其双光子能量转移效率增大的物理原因. 同时, 研究了罗丹明B浓度对荧光共振能量转移效率的影响. 研究结果表明, 量子点的荧光寿命随着罗丹明B浓度的增加而减小; 量子点与罗丹明B之间的荧光共振能量转移效率随着罗丹明B浓度的增加而增加; 当罗丹明B浓度为3.0×10^-5 mol·L^-1时, 双光子荧光共振能量转移效率为40.1%.     

Dy-doped Lu2SiO5 single crystal: spectroscopic characteristics and luminescence dynamics

Spectroscopic and kinetics properties of Lu₂SiO₅:Dy³⁺ (LSO:Dy) single crystal with 1 and 5 at.% of activator were investigated. The polarised absorption and unpolarised emission spectra were measured at 10–300 K. Parameters characterising radiative relaxations of LSO:Dy were estimated by the Judd–Ofelt model. The crystal-field energy structure was derived from low-temperature optical spectra exhibiting the presence of two non-equivalent Dy³⁺ sites. It was found that dysprosium ions in site 1 and in site 2 do not form isolated subsystems; these subsystems are coupled by an effective spectral energy migration process. The LSO:Dy crystal exhibits a strong luminescence in the visible. Strong ion–ion interactions were observed for LSO:Dy (5 at.%); luminescence decays are non-exponential and the macro-parameter of donor–acceptor interaction C _da amounts to 5.3 (10^?52 m⁶?s^?1) and 7.8 (10^?52 m⁶?s^?1) at 10 and 300 K, respectively. Laser potential related to the ⁴F_9/2→⁶H_13/2 yellow luminescence in Dy:LSO was assessed based on evaluation of the emission cross section values. It was concluded that the crystal is a promising material for visible laser operation.     

Experimental investigations on energy-transfer characteristics and performance of some laser dye mixtures

Energy transfer from both Coumarin 120 (C120) and p-Bis(o-methylstyryl)-benzene (Bis-MSB), energy donors, to coumarin 7(C7) (acceptor) individually has been studied by steady-state emission measurements in methanol. The dye laser characteristics of the above-mentioned dyes have also been studied with respect to the energy transfer mechanism in the same solvent using a pulsed nitrogen laser as a pumping source. The large values of the critical transfer distances, R₀, indicate that the dominant mechanism responsible for energy transfer is due to long-range dipole–dipole interaction between the excited donor and ground state acceptor molecule. Both photophysical and photochemical stability of the donors has been examined under the effect of N₂ laser pumping.     

GaN薄膜的蓝光和红光发射机理研究

由于生长工艺的不完善，非掺杂GaN薄膜中通常存在未知的杂质和缺陷，产生与这些未知杂质和缺陷能级相关的发光。报道了非掺杂GaN薄膜的692nm红色发光．并研究了非掺杂GaN薄膜的蓝、红色发光的发射机理；利用作者提出的吸收归一化光致发光激发光谱，直接测量出了非掺杂GaN薄膜的蓝、红色发光的初始态能级，确定蓝色发光为施主-价带跃迁复合，而红色发光为施主-受主跃迁复合；给出了黄、蓝、红光的发射模型。所取得的结果对于确定未知杂质和缺陷的种类具有重要的参考价值。     

Effect of the Temperature on the Phosphorescence and Absorption Parameters of the Energy Donor in Frozen Paraffin Solutions

The effect of temperature on the luminescence and absorption characteristics of the donor-acceptor benzophenone-naphthalene mixture in a frozen n-octane solution is investigated. The main mechanisms of increase in the phosphorescence intensity of energy donor and acceptor molecules after solution annealing are established.