不同波长激发光对血清荧光光谱影响的实验研究

采用日本岛津荧光光度计RF5301,研究了血清的荧光光谱与激发光波长的关系。实验结果表明：在不同波长的紫外光激励下,血清产生的荧光光谱线型及峰值波长基本相同,与激励光波长无关,但荧光峰强度随激励光波长变化而变化。血清的荧光光谱有两个较强的荧光发射区,其中第一个发射区处于300～410 nm,第二个发射区处于410～530 nm。当激发光波长小于310 nm,荧光主要集中在第一发射区,荧光峰位于330和370 nm处,并产生竞争现象。当激发光波长大于250 nm时,只出现330 nm处的荧光峰,其最佳激励光波长为300 nm;当激发光波长大于320 nm,第一发射区的荧光变弱,在第二发射区的荧光变强,荧光峰位于452 nm。此研究为血液的光谱特性研究提供了实验依据,对光诱导荧光光谱诊断技术中激发光波长的选择具有一定的参考价值。     

激光波长对荧光激发谱分布影响研究

激光器是DNA测序仪中的重要部件,寻求合适波长的激光器可有效提高DNA测序仪性能。分析了DNA检测所用的四种荧光染料FAM、JOE、TAMRA和ROX的激发谱和发射谱,设计实验技术方案利用488nm、505nm和515nm三种不同波长的激光器分别对其进行激发。在相同的积分时间和相同的功率下,488nm激光器对于荧光染料ROX的激发强度太低,515nm激光器对于荧光染料FAM的激发强度太低,而505nm激光器对于四种荧光染料的激发强度均比较强。实验结果表明在三种不同波长中,505nm激光器对四种荧光染料的激发效果最佳,可以替代目前大多数DNA测序仪中的氩离子激光器。     

不同荧光波长的双光子共焦成像分析

研究了双光子共焦显微镜中不同荧光波长对成像特性的影响,导出了不同荧光波长的三维脉冲响应函数和三维光学传递函数并进行数值计算.研究结果表明：不同荧光波长对双光子共焦显微镜的三维光学传递函数、三维脉冲响应函数和空间截止频率产生明显的影响,随着荧光波长的增大,分辨率明显下降,但不会出现单光子共焦显微镜中的失锥现象,选取适当的荧光波长进行成像,有利于进一步改善图像分辨率和成像质量.     

不同溶剂中番茄红素的荧光光谱及其特性研究

用970CRT荧光光度计测定了番茄红素在正己烷、乙酸乙酯、四氢呋喃、氯仿、丙酮和苯等6种溶剂中的荧光光谱以及番茄红素在四氢呋喃溶液中不同浓度下的荧光光谱。对所测光谱分析得出:6种溶剂中荧光光谱的最大峰值波长(λmax)分别为542.5 nm5、48.2 nm5、55.0 nm、555.7 nm、556.4 nm和565.7 nm,由于溶剂效应,随溶剂极性由小到大,荧光光谱的最大峰值波长(λmax)逐渐红移,由这些峰值波长计算得出相应的番茄红素分子在6种溶剂中的跃迁能ET分别为220.5 kJ/mol2、18.2 kJ/mol2、15.6 kJ/mol2、15.3 kJ/mol2、14.9 kJ/mol和211.5 kJ/mol,可见跃迁能ET也随溶剂极性增大而降低;当番茄红素在四氢呋喃溶液中的质量浓度低于50μg/ml时,溶液的荧光强度随溶液浓度增加而增大,当质量浓度高于50μg/ml时,由于番茄红素的激发态分子与基态分子相互作用,荧光强度反而减小;在浓度低于80μg/ml的溶液中,番茄红素的荧光光谱除最大峰值外还有三个较小峰值,据此计算得出相应的番茄红素分子的跃迁能分别为E(T1)=278.2 kJ/mol、E(T2)=260.2 kJ/mol和E(T3)=239.3 kJ/mol。     

不同波长激发光诱导奶牛血液荧光光谱特性

实验样品取自正常奶牛静脉血液并用枸橼酸钠抗凝。实验结果表明:激发光波长不同,激发的荧光光谱线的强度和峰值不同;实验中用220～270nm波长的光激发荧光时,在317,367nm荧光主峰强度出现竞争现象;比较多种激发光激发的荧光光谱的实验结果知:用220,230,240,290,350,480,500nm波长的激发光激发下的荧光强度较强,而用其他波长的激发光激发下的荧光强度较弱,且在317,365,367,388,348,463,467,607,638nm波长附近出现比较强的峰值;合适波长的激发光对奶牛血液会有比较强的生物学效应。     

超高压下红宝石荧光R线的猝灭压力与入射激发线波长的关系

 分别使用固态氩和体积比为4∶1的甲醇-乙醇混合溶液做传压介质，测量红宝石在这两种介质中的荧光光谱随压力的变化。首先发现在超高压下红宝石荧光R线的压致猝灭与入射激发线波长以及高压样品室内的静水压程度有关。实验结果表明：入射激发线的波长越长，荧光R线的猝灭压力越低；对同一激发线波长，静水压程度差，猝灭压力高。这一现象归因于红宝石吸收谱中U带和Y带随压力的蓝移。     

基于指示克立格法的最佳激发波长和最佳发射波长的确定

激发波长和发射波长是分子荧光光谱测量的重要参数,它的选择影响分子荧光光谱的测量以及其后续研究的精确度。由于如HITACHI F-4500 荧光分光光度计等一些光谱仪器的测量精度达不到一些光谱分析技术的要求以及测量数据的有限,在实际工作中,利用已测量的光谱数据,通过插值生成所需要的光谱数据,就成为一种有效的解决方法。因此,文章使用指示克立格法对一定体积分数的乙醇溶液的最佳激发波长和最佳发射波长的确定进行了研究。基于指示克立格法求取的最佳激发波长和最佳发射波长分别是226.9和337.1 nm,经验证其值是准确的。此外,文章采用相对标准偏差对插值结果进行了评价。结果表明在分子荧光光谱测量中基于指示克立格法确定最佳激发波长和最佳发射波长是可行的,这为最佳激发波长和最佳发射波长的确定提供了一种新的方法。     

溶剂对石墨烯量子点荧光性质的影响

采用柠檬酸热解法制备了石墨烯量子点(GQDs),研究了非极性溶剂戊烷,极性溶剂乙醇、丙酮、乙二醇对GQDs荧光性质的影响。透射电子显微镜(TEM)和原子力显微镜(AFM)图像表明,制备的GQDs尺寸分布在2~12 nm(平均尺寸为4.9 nm),分散均匀,高度分布在0.5~2 nm。吸收光谱表明,GQDs具有明显的紫外吸收特性,吸收峰位于259 nm和274 nm。光致发光谱表明,GQDs的发光具有明显的溶剂依赖性。GQDs在极性溶剂乙醇、丙酮、乙二醇中,发光峰的位置依赖于激发波长,发射波长在可见光区。而在非极性溶剂戊烷中,GQDs表现出对激发波长不依赖的荧光性能,且发射波长在近紫外。     

荧光产生时间与荧光峰值波长关系的研究

用激光诱导荧光(LIF)方法对芳香族化合物蒽进行了时间分辨谱研究,介绍了所用测试系统的组成和测试方法,获得了蒽的荧光强度-波长-时间三维立体图、峰值荧光时间图、等高图,并对实验结果进行了分析。研究表明,荧光产生的时间与峰值波长有关系,长波早于短波。     

荧光波长对共焦显微镜成像特性的影响

导出了共焦显微镜中不同荧光波长情况下的荧光功率传输函数、三维脉冲响应函数（3D－PSF）和三维光学传递函数（3D－OTF）。结果表明，不同的荧光波长对共焦显微镜的空间截止频率、分辨率、光学传递函数存在明显的影响。当激发波长与荧光波长的比值下降到一定程度时，可以看到明显的失锥现象。     

Dependence of photoluminescence of CdSe/ZnS on excitation wavelength

We have found that the photoluminescence (PL) intensity of CdSe/ZnS nanocrystals placed on a thin film of insulator (GaAsOx/GaAs) depends on excitation wavelength through the interference effects of the excitation light. By employing the multi-reflection/interference calculation, the insulator thickness of the underlying non-uniform patterns can be evaluated by the simple observation of CdSe/ZnS PL with a couple of excitation wavelengths. Moreover, the differences observed for the temporal evolution of CdSe/ZnS PL (blue shifts and degradation) among the excitation wavelengths suggest that the photo-induced changes of chemical composition and surface ligands are responsible for blue shifts and degradation, respectively.     

Dependence of the annihilation pressure of ruby R-line fluorescence on the laser exciting wavelength

Abstract

Using solid argon as pressure medium, quasi-hydrostatic pressure was obtained at room temperature in the diamond cell up to 90 GPa. The mechanism of the disappearance of ruby R lines and the applicability of ruby pressure scale under quasi-hydrostatic pressure above 100 GPa was discussed. The deviation of every pressure measured at nine positions in the cell per mean pressure was less than 1.5% at pressure below 80 GPa.     

The strontium-vapor laser pumping efficiency under running-wave excitation

The effect of the design features of the gas-discharge tube on the processes proceeding in the discharge circuit of a metal-vapor laser has been investigated. The position of electrodes in the gas-discharge tube has been found to significantly affect the processes at work in the discharge circuit and the energy characteristics of the laser. For instance, gas-discharge tubes with electrodes placed in the hot region of the discharge channel are typified by high metastable-population rates at the leading edge of the excitation pulse, whereas with electrodes positioned in cold buffer regions, the leading edge of the voltage pulse across the resistive component of the tube impedance is seen to peak. Conditions for running-wave generation in the active media of lasers on self-terminated transitions of metal atoms and the running-wave use efficiency for laser pumping are discussed, considering a strontium-vapor laser as an illustration. It is shown that the running wave is generated as the result of the breakdown in the anode end of the gas-discharge tube and is maintained by the energy stored in the capacitive component of the impedance of the gas-discharge tube. The lasing pulse duration under running-wave excitation corresponds to the time it takes an ionization wave to propagate from the anode to the cathode of the gas-discharge tube, with pumping efficiency being ~6–8% for a strontium-vapor laser. The average lasing power varies within 10–15% depending on whether the totally reflecting cavity mirror is placed near the anode or the cathode of the tube. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 79–87, December, 2008.     

绿光LED激发荧光的研究

介绍了绿光LED作为荧光激发光源的可行性。使用波长为 5 30nm的超高亮度绿光LED对荧光物质四氯四溴荧光素 (C2 0 H2 Br4 Cl4 Na2 O5)的荧光发射进行了研究。设计了小巧的荧光液池 ,将四个LED分别安置于液池侧面 ,聚光后的光束交汇于液池中同一位置以提高激发光的强度 ;使用 1kHz方波调制LED ,运用分光光度计方法 ,接收到波长为 5 70nm的荧光信号     

Dependence of lasing threshold power on excitation wavelength in dye-doped cholesteric liquid crystals

Relationship between threshold power and excitation wavelength has been investigated in distributed feedback (DFB) lasers using dye-doped cholesteric liquid crystals (CLCs). We found that the threshold shows strong dependence on the excitation wavelength. The excitation wavelength was varied over the whole absorption band of a commercial DCM dye, resulting in almost one-order of magnitude lower threshold power by the excitation at the higher energy tail than at the lower energy tail of the absorption band. We confirmed the existence of an optimum wavelength giving the lowest threshold power due to the competition between this effect and decreasing absorption at the higer-energy tail of the absorption band using a different dye, pyromethene 580.     

Dependence of the properties of the dual luminescence of 3-hydroxyflavone on the excitation wavelength

The luminescence and luminescence excitation spectra of 3-hydroxyflavone in acetonitrile obtained at different excitation/recording wavelengths are studied. The dependences of the position of the normal luminescence band maximum and of the intensity ratio of the normal and proton-transfer bands, on the excitation wavelength are found and studied for the first time. It is found that the spectral contour of dual luminescence also depends on the excitation wavelength and the blue emission band is cut off at a sufficiently long-wavelength excitation in the region of 390 nm. In the luminescence excitation spectrum, an additional wide band is observed in the proton-transfer region at 200–260 nm. Excitation in the region of 380–440 nm allowed us to reveal a wide structureless band near 470 nm (with the maximum of its excitation near 420 nm) belonging to the anionic form of 3-hydroxyflavone. Addition of water at a concentration of ～2.2 M quenches this band almost completely.     

Excitation efficiency measurement in multimode solid-state lasers

Designing solid-state laser systems for various applications is an important subject in the laser industry. Excitation efficiency and the losses of such a laser are the main parameters sought. Both parameters can be measured using a method first published by Findlay and Clay, but measurements of efficiency and losses of several laser cavities showed that the applied technique may fail sometimes. In this note a detailed investigation is reported about the measuring technique for the losses and excitation efficiency of a solid-state laser. It is shown that limitations of the model mislead, and give false results under different experimental conditions, and it is described how to overcome the difficulties outlined here.