Y_2O_2S∶Tb纳米晶的能量传递过程的研究

研究了Y2O2S∶Tb纳米晶的发光性质和能量传递过程,根据浓度猝灭曲线分析了纳米Y2O2S中引起5D3和5D4能级浓度猝灭的相互作用类型分别为电偶极-电偶极和交换相互作用。纳米Y2O2S中Tb离子的5D3-7F5跃迁的发光寿命与相同掺杂浓度的体材料相比明显缩短,根据引起浓度猝灭的相互作用类型对发光衰减曲线进行拟合,得到理论和试验一致的结果。     

Y2O2S：Tb纳米晶的能量传递过程的研究

研究了Y2O2S：Tb纳米晶的发光性质和能量传递过程，根据浓度猝灭曲线分析了纳米Y2O2S中引起^5D3和^5D4能级浓度猝灭的相互作用类型分别为电偶极-电偶极和交换相互作用。纳米Y2O2S中Tb离子^5D3-^7F3跃迁的发光寿命与相同掺杂浓度的体材料相比明显缩短，根据引起浓度猝灭的相互作用类型对发光衰减曲线进行拟合，得到理论和试验一致的结果。     

卤铂酸-人血清白蛋白体系的瑞利散射光谱研究及分析应用

在pH4．4的NaAc-HAc缓冲溶液中,人血清白蛋白(HSA)在350nm有1个荧光峰,而瑞利散射较弱。当PtCl6^2-存在时,其与HSA之间由于静电引力和疏水作用力而形成PtCl6^2--HSA微粒,在470nm处产生较强的瑞利散射峰。HSA浓度在2～30μg／mL时与I470nm呈线性关系。研究结果表明,PtCl6^2--HSA缔合微粒的形成是导致体系瑞利散射增强和荧光猝灭的根本原因。     

荧光方法测量应力

开展应力的无损测量方法研究对应力测量具有重要意义。介绍了6种利用荧光测量应力的方法:Cr3+荧光压谱效应、拉曼压谱效应、稀土荧光压谱效应、荧光寿命和氧分压相关的荧光猝灭,简述了它们的基本原理及应用,分析了各自的优点和局限性,对这些方法在航空航天机械的健康监测、可靠性评估、失效预期等方面的发展前景作了展望。     

铂类抗肿瘤药物甲啶铂的水合反应研究

采用高效液相色谱研究了抗肿瘤药物甲啶铂的水合反应,以及甲啶铂在0.9%NaCl溶液中的稳定性。结果表明,甲啶铂的水合反应遵循一级反应动力学规律,20℃时反应速率常数为k=0.03086h-1,半衰期22.5 h,反应活化能E=80.6 kJ/mol;在0.9%NaCl溶液中,甲啶铂的水合反应被抑制,反应达到平衡后,甲啶铂的降解不超过4%。     

铂类抗肿瘤药物甲啶铂破坏性试验研究

根据药品稳定性试验的要求,采用高效液相色谱分析方法研究甲啶铂在酸、碱、氧化和还原条件下的稳定性,并研究了不同p H值对甲啶铂稳定性的影响,所有溶剂均用0.9%Na Cl溶液配制。研究结果表明,甲啶铂在0.01 mol/L HCl溶液中放置24 h含量降解约7%;在0.01 mol/L Na OH溶液中放置24 h含量降解约78%;在0.3%H2O2溶液中放置24 h含量降解约49%;在0.01%Na HSO3溶液中放置24 h含量降解约9%;p H太高或者太低均不利于甲啶铂的稳定,最稳定的p H在3~5之间。结果说明,甲啶铂在碱性和氧化性环境中极不稳定,在还原性和酸性环境中相对稳定,但还原剂和酸的加入量需严格控制。     

甲啶铂在玻碳电极上的电化学行为及其与DNA相互作用研究

采用循环伏安法(CV)和差分脉冲伏安法(DPV),研究了甲啶铂在多壁碳纳米管-离子液体修饰玻碳电极(MWNTs-[ODMIM]PF6/GCE)上的电化学行为,建立了甲啶铂的测定方法;以紫外-可见光谱法和电化学方法相结合,研究了甲啶铂与DNA的嵌插结合作用。结果表明:甲啶铂在MWNTs-[ODMIM]PF6/GCE上有一对氧化还原峰,氧化峰电位Epa与还原峰电位Epc分别为-0.07 V、-0.36 V,峰电位之差为ΔE=0.29 V,Ipa/Ipc=1.11。在优化条件下,甲啶铂的氧化峰电流与其浓度在2.66~532μmol/L范围内成良好的线性关系(r=0.9994),检出限为1.33μmol/L。方法操作简便,准确可靠、灵敏度高,可用于甲啶铂含量的直接测定。     

KLa(MoO_4)_2:Sm~(3+),Eu~(3+)荧光粉中能量传递研究

采用高温固相法合成了KLa0.7-x(MoO4)2:0.3Eu3+,xSm3+系列红色发射荧光粉,利用XRD对样品的晶体结构进行了分析,发现所得到的样品均为纯相。采用荧光光谱手段对样品的发光性质及能量传递进行了研究。在低Sm3+掺杂浓度时采用277及394 nm激发样品,其发光强度几乎不随掺杂浓度变化,若利用404 nm激发样品发光随Sm3+浓度有明显增强;当Sm3+掺杂浓度较高时,利用277,394及404 nm激发观察到了Sm3+对Eu3+发光产生了猝灭作用。采用电多极相互作用模型及交换相互作用模型对Sm3+到Eu3+的能量传递过程的物理本质进行了探讨,确定了在低掺杂浓度下Sm3+到Eu3+的能量传递是基于交换相互作用的结果。通过对Eu3+的5D0能级荧光动力学过程的分析进一步证实了在低Sm3+掺杂浓度时Sm3+充当能量传递供体,而高掺杂浓度时Sm3+对Eu3+发光产生了猝灭作用。     

铜表面苯丙氨酸和色氨酸复合自组装膜的缓蚀性能研究

用电化学极化和电化学阻抗方法研究3%NaCl溶液中苯丙氨酸和色氨酸复合自组装膜对铜的保护作用,通过荧光分析法讨论了复合自组装膜中苯丙氨酸与色氨酸之间的相互作用。结果表明,两种氨基酸对铜均有一定的保护效果,但复合自组装膜相互之间存在拮抗作用,影响了氨基酸自组装膜的保护效率。     

抗肿瘤新药甲啶铂的合成工艺研究

为合成抗肿瘤药物甲啶铂，采用醋酸铵与K2PtCl4反应生成K[Pt(NH3)Cl3]，再先后与碘化钾、2-甲基吡啶、硝酸银、氯化钾反应生成甲啶铂。采用元素分析、质谱、核磁共振氢谱和红外光谱对其结构进行了表征。结果显示合成的化合物与理论一致，产率约为40%，可为甲啶铂的合成提供一条新的工艺路线。     

Absorption and emission spectral studies of Sm-doped lead tungstate tellurite glasses

The present work reports the effect of concentration on photoluminescence properties of Sm³⁺ ions doped lead tungstate tellurite (LTTSm) glasses by using the absorption, emission and decay measurements. The Judd-Ofelt theory has been used to evaluate the three Judd-Ofelt intensity parameters (Ω_2,4,6) and calculated oscillator strengths (f_c). LTTSm glasses exhibited intense reddish-orange emission when excited with 477 nm wavelength. Concentration quenching has been noticed beyond 1.0 mol% of Sm³⁺ ion concentration. The decay curves of ⁴G_5/2 level exhibited single exponential behavior for all the concentrations and the measured lifetimes are found to depend strongly on Sm³⁺ concentration. From the emission characteristic parameters of ⁴G_5/2 level, it is concluded that the LTTSm glasses could be useful for photonic devices like visible lasers, fluorescent display devices and optical amplifiers.     

Preparation and luminescent characteristics of Sr3RE2(BO3)4:Dy (RE = Y, La, Gd) phosphors for white LED

Dysprosium-activated Sr₃RE₂(BO₃)₄ (RE = Y, La, Gd) phosphors were synthesized by a high temperature solid-state reaction method. The phase uniformity of the phosphors was characterized by X-ray powder diffraction (XRD) and the luminescence characteristics were investigated. The excitation spectra at 575 nm emission show strong spectral bands in the region of 300-500 nm. The emission spectra of the phosphors with 365 nm excitation show three bands centered at 484 nm, 575 nm and 680 nm, which originate from the transitions of ⁴F_9/2 → ⁶H_15/2, ⁴F_9/2 → ⁶H_13/2 and ⁴F_9/2 → ⁶H_11/2 of Dy³⁺, respectively. The effect of Dy³⁺ concentration on the emission intensity of the phosphors was investigated. The fluorescence decay curves for ⁴F_9/2 → ⁶H_13/2 excited at 365 nm and monitored at λ_em of 575 nm were measured. The decay times decreased slowly with increasing Dy³⁺ doping concentration due to a trap capturing to resonance fluorescence transfer of the activated ions and due to the exchange interactions between activated ion pairs. In order to determine the type of interaction between activated ions, the concentration dependence curves (lg(I/x) versus lg x) of Sr₃RE₂(BO₃)₄:Dy³⁺ (RE = Y, La, Gd) were plotted. The concentration quenching mechanism of the ⁴F_9/2 → ⁶H_13/2 (575 nm) transition of Dy³⁺ is the d-d interaction. All results indicate these phosphors are promising white-color luminescent materials.     

Preparation and performance of fluorescent sensing coating for monitoring corrosion of Al alloy 2024

A kind of fluorescent sensing coating was prepared for monitoring corrosion of aluminum alloys by incorporating phenylfluorone（PF） into acrylic paint as sensing material. The fluorescent dye PF reacts with aluminum ions on corroded aluminum substrate to occur fluorescence quenching observed in UV light. This paint system is sensitive tO underlying corrosion processes through reacting with the Al^3＋ produced by anodic reaction accompanying corrosion. After a certain time, when the samples of Al alloy 2024 coated with PF-acrylic paint were immersed in 1 mol/L NaCl solution, fluorescence quenching spots can be seen with unaided eyes. With the development of corrosion process, the size of fluorescence quenching spots increases. Active corrosion areas on the sample surface were found under the fluorescence quenching spots by optical microscope. The corrosion areas can be observed more clearly by SEM, and many pits are found. This suggests that the fluorescence quenching spots are the sites of produced Al^3＋ by the anodic reaction of the local attack of the coated Al alloy substrate in the chloride solution and the corrosion process of the coated AI alloy can be monitored on-line by the sensing coating. The sensitivity of this coating system for detection of anodic reaction associated with corrosion was determined by applying constant charge current and measuring the charge, at which fluorescence quenching is detected in the coating with unaided eyes. Visual observation of coated samples can detect fluorescence change resulting from a charge corresponding to an equivalent hemispherical pit with approximate depth of 50 μn.     

Photoluminescence and time-resolved luminescence spectroscopy of novel NaBa4(BO3)3:Tb phosphor

This paper reports the photoluminescence (PL) properties of Tb³⁺ in NaBa₄(BO₃)₃, as well as the time-resolved luminescence properties. The PL excitation spectrum exhibits intense f → f transition absorption; the PL emission spectrum shows the strongest ⁵D₄ → ⁷F₅ emission at 540 nm. The relative intensity of ⁵D₃ emission is much weaker than that of ⁵D₄ emission even in the samples with lower Tb³⁺ concentration. The ⁵D₃ → ⁵D₄ cross-relaxation produces a marked increase in the ⁵D₃ decay rate with increasing Tb³⁺ concentrations and introduces a non-exponential component into the initial part of the decay. The dipole-dipole interaction is found to be responsible for the cross-relaxation. The decay curves of ⁵D₄ → ⁷F₅ transition exhibit an initial rise phenomenon. The two exponential fitting indicates that the initial slow rise is attributed to the ⁵D₃ → ⁵D₄ cross-relaxation process.     

Changes of fluorescent spectral features after successive rare earth doping of gadolinium oxide powders

We present a complex fluorescence study of a series of gadolinium oxide polycrystalline powders singly, doubly and triply doped with trivalent rare earth ions (Er³⁺, Tb³⁺, and Dy³⁺), to explore a possibility of their use as materials for white light emitting diodes. The excitation and luminescence spectra along with the decay kinetics were measured in the temperature range from 6 to 300 K. The luminescence efficiency was studied within the visible spectral range, i.e. −400 nm to 750 nm under excitation by 355 nm third harmonic Nd:YAG laser pulses. Singly doped Er³⁺ sample gave stronger luminescence signals, but others showed significantly larger decay lifetimes. The successive rare earths doping leads to substantial changes of the spectral positions due to the up-conversion processes. In the singly (Er³⁺) doped sample, following the time resolved spectrum and decay curves, there are two different types of emissions: at 660 nm and at shorter wavelengths (below 640 nm) the red emission's lifetime is ten times longer than at shorter wavelengths. The singly doped sample shows unclear temperature-dependence of luminescence with lifetime at 550 nm (the longest at 100 K, similarly at 6 K and 300 K) and achieved luminous efficacy 73.5 lm/W.     

Optical properties of Yb-doped phosphate laser glasses

Ytterbium-doped phosphate glasses have been prepared and studied their spectroscopic properties through absorption, emission and Fourier transform infrared (FTIR) spectral studies and time-resolved luminescence decay curves. The absorption cross-section has been found to vary with the variation of Yb₂O₃ concentration. The results of the FTIR spectra show that the OH⁻ content is increasing with increase of the Yb₂O₃ concentration in these glasses. The decay curves of the ²F_5/2 level of Yb³⁺ ions exhibit a single exponential nature for all the concentrations. The lifetimes of the ²F_5/2 level of Yb³⁺ ions decreases from 1.04 to 0.27 ms when the Yb₂O₃ concentration is increased from 0.1 to 6.0 mol%. The quenching of lifetimes has been found to vary directly with the inter-ionic distance between the Yb³⁺ ions. The concentration quenching of the lifetime has been analyzed using different energy transfer processes and no evidence of cooperative luminescence of Yb³⁺ ions has been found in these glasses, which reveals that the present glasses are useful for photonic device applications. The laser performance properties have also been evaluated for these glasses and compared with those of other reported Yb³⁺-doped glass systems.     

Spectroscopic properties of Yb in NaYbP2O7 diphosphate single crystals

Yb³⁺ absorption and fluorescent emissions were investigated for NaYbP₂O₇ diphosphate single crystals. The interpretation of electronic energy level positions has been done by using the comparison of absorption and emission spectra with those of vibronic sideband energy positions from Raman and IR absorption spectroscopies. The Yb³⁺ energy levels scheme in this host was drawn. The decay time for infrared Yb³⁺ (⁵F_5/2 excited state) fluorescence was in the range of 1–2 ms. The interest feature is leading to broad emission band at room temperature from 940 nm to 1100 nm, which seems of high interest for ultra-short laser pulse production.     

Thermophysical properties of refractory W-50.4%Re and Mo-39.5%Re thin alloy layers deposited on silicon and silica substrates

The examined samples were W-Re and Mo-Re thin alloy layers with high content of Rhenium, applied in industry as protective coatings. The 550 nm of W-50.4%Re and 580 nm of Mo-39.5%Re alloys were deposited on crystalline silicon and amorphous silica substrates by magnetron sputtering method. For thermal characterization of investigated layers the scanning thermal microscopy (SThM) and high frequency photothermal radiometry (HF-PTR) measurements were carried out. The thermal methods were supported by the microstructural studies performed by the atomic force microscopy (AFM) and X-ray diffraction (XRD). The SThM method allowed determining the thermal conductivity (κ) of the alloy layers. From the HF-PTR the effective thermal conductivity (κ_eff) was determined directly. Estimation of the thermal boundary resistance (R_th) between particular alloy layer and its substrate enabled determination of the real κ of the layer with its thermal diffusivity (α) and effusivity (ε) from the HF-PTR fitting. The results showed, that W-Re and Mo-Re layers deposited on Si are characterized by higher κ, α, and ε values, and lower R_th in comparison to those deposited on SiO₂. The κ values for W-Re and Mo-Re layers deposited on Si and SiO₂ substrates were estimated in the range from 7 W·m⁻¹ K⁻¹ to 12 W·m⁻¹ K⁻¹, and 1.6 W·m⁻¹ K⁻¹ to 4 W·m⁻¹ K⁻¹, respectively. The correlation between the alloy layer structure, it's thermophysical properties and substrate structure was observed. The AFM and XRD measurements confirmed the short range order formation in Mo-Re layers deposited on Si.