基于激光诱导荧光法的同轴射流火焰中羟基自由基、甲醛、发热率与一氧化氮的二维可视化测量

对现有单一组分羟基自由基(OH)平面激光诱导荧光系统(PLIF)装置进行功能扩展研发,在不增加激光器和探测器的情况下,拓展了甲醛(CH2 O)、发热率(heat release rate,HRR)和一氧化氮(NO)三个参量的PLIF成像测试模块.同时,利用所研制的同轴射流火焰装置开展了所建立的多参量PLIF测量技术的实...     

OH在火焰中浓度分布图像及与温度关系的PLIF和CARS研究

用平面激光诱光（ＰＬＩＦ）技术了平面火焰炉、狭缝缝火焰的单脉冲激光诱导ＯＨ荧炙。由平面荧光图可得到氢氧基相对浓度分布和它的宽度。对扩散火焰,高温区在ＯＨ带内侧;ＯＨ带的外侧则是火焰的边界,相干反斯托克斯拉斯拉曼光谱（ＣＡＲＳ）的测量结果对比提出了有力的佐证。湍流火焰的ＰＬＩＦ图则清晰地显示出火焰面的不规则性,氢氧基的ＰＬＩＦ图像是研究火焰结构和流场的有力工具。     

激光诱导荧光光谱分析进展

本文对激光诱导荧光光谱分析的研究现状和发展趋势进行了综述。着重介绍了激光诱导原子荧光光谱、激光诱导分子荧光光谱、激光低温光谱,时间分辨光谱和激光诱导荧光光谱与其它分析技术的联用研究。     

C_(60)-苯并噻吩吡咯烷的合成及非线性光学性质的研究

设计合成了一种C60-苯并噻吩吡咯烷衍生物(2),以1HNMR、13CNMR、FTIR、UV-Vis和FAB-MS进行了结构表征。由其在甲苯溶液中的紫外光谱和荧光发射光谱测得,在最大发射波长下的荧光寿命为5.34ns。Z-扫描技术测得其分子三阶非线性极化率γ(3)为1.82×10-33esu,大于C60的文献报道值7.5×10-34esu,表明在激光激发下苯并噻吩与C60之间发生了分子内能量转移和电荷传递。理论计算结果进一步佐证了电荷转移的发生。     

Eu3+,Tb3+混配配合物的激光诱导荧光

利用激光诱导荧光技术研究了两种三价稀土金属离子的β－二酮与有机配体混配络合物中金属离子的寿命及其能级结构，得到了Ｅｕ＾３＋的能级常数。     

激光诱导荧光辅助激光诱导击穿光谱检测有源发光玻璃中的微量元素

在有源发光玻璃的制备过程中,通常需要掺杂微量元素,用于改善玻璃的发光性能,因此在生产过程中进行快速检测非常重要.本实验针对激光诱导击穿光谱技术(LIBS)分析玻璃中微量元素灵敏度不足的问题,利用激光诱导荧光辅助激光诱导击穿光谱技术(LIBS-LIF)检测了玻璃中3种微量元素Yb,Al和P.使用波长可调谐激光激发等离子体中的Yb+离子、Al原子和P原子,并对这3种粒子在激光诱导荧光中的跃迁过程进行了分析.结果表明,通过激光诱导荧光辅助激光诱导击穿光谱技术,Yb+离子、Al原子和P原子的光谱强度分别增强了23,50和8倍,大幅度提高了LIBS分析的灵敏度.     

维生素C纳米脂质体的制备及抗氧化作用的研究

本论文以自行提取的蛋黄卵磷脂为原料,采用薄膜-超声法制备了包含有抗氧化物质Vc的脂质体微囊。以鸡蛋外膜模拟皮肤角质层结构,利用Fenton试剂引入羟基自由基诱导其表面损伤,利用扫描电镜SEM研究了包囊维生素C脂质体对鸡蛋外膜的抗氧化作用效果。以Pyrene为荧光探针,利用荧光探针技术从分子水平上研究了Vc脂质体对羟基自由基的捕获作用。     

微流控芯片荧光检测系统研究进展

评述了1996～2010年以来微流控芯片荧光检测系统的研究进展,主要介绍微流控芯片中荧光检测系统,包括激光诱导荧光（LIF）、发光二极管（LED）诱导荧光和其他荧光检测装置的原理、光路结构及其应用（引用文献60篇）。     

由激光诱导荧光方法探测光碎片分子取向的理论研究

采用密度矩阵方法,推导了从激光诱导荧光(LIF)强度中抽出光碎片取向参数的表达式.光碎片的取向由分子态多极矩描述.用于解离母分子和激发碎片分子的激光均为线偏振光,而探测荧光为非偏振光.激光诱导荧光强度是光碎片分子初始态多极矩、线强度因子和解离-激发几何因子的函数.光碎片的取向参数可以由测量荧光偏振比和计算动力学因子而获得.     

高效毛细管电泳-激光诱导荧光技术在荧光标记DNA分析中的研究进展

激光诱导荧光检测器是目前最灵敏的检测器之一,已广泛用于毛细管电泳DNA分析中.该文对毛细管电泳-激光诱导荧光技术在DNA分析中3种主要的DNA荧光标记方式:荧光基团共价标记、PCR后标记、内插荧光染料标记进行了综述,并对其发展前景进行了展望.引用了78篇文献.     

Laser induced double-resonance ionic fluorescence in an inductively coupled plasma

Two pulsed dye lasers pumped by an excimer laser are simultaneously directed into the analytical zone of an inductively coupled argon plasma. When the two beams are tuned to the appropriate ionic transitions, highly excited ionic levels can be efficiently populated in saturated conditions, the resulting fluorescence being then spectrally isolated with a monochromator and measured. A theoretical outline of this technique, variously called double-resonance fluorescence or two-step fluorescence, is given. The experimental results obtained with the alkaline-earth metals Ca, Sr, Ba and Mg show that the technique does provide excellent sensitivity, freedom from scattering problems and unprecedented spectral selectivity. The laser characteristics, the time overlap between the pulses and the spectral characteristics of the transitions used are discussed. Finally, ionic fluorescence in the plasma is the most suitable analytical application of such double-resonance technique since its use in flame atomic fluorescence suffers from the strong depletion of the excited levels due to collisionally assisted ionization.     

Laser-induced fluorescence of formaldehyde in combustion using third harmonic Nd:YAG laser excitation

Formaldehyde (CH2O) is an important intermediate species in combustion processes and it can through laser-induced fluorescence measurements be used for instantaneous flame front detection. The present study has focussed on the use of the third harmonic of a Nd:YAG laser at 355 nm as excitation wavelength for formaldehyde, and different dimethyl ether (C2H6O) flames were used as sources of formaldehyde in the experiments. The investigations included studies of the overlap between the laser profile and the absorption lines of formaldehyde, saturation effects and the potential occurrence of laser-induced photochemistry. The technique was applied for detection of formaldehyde in an internal combustion engine operated both as a spark ignition engine and as a homogenous charge compression ignition engine.     

Laser excited atomic fluorescence of some transition elements in the nitrons oxide-acetylene flame

A pulsed, tunable dye laser, pumped with a nitrogen laser is used to excite the atomic fluorescence of Sc, V, Hf, Nb, Os, Zr, W, Rh and Ru. Except in the case of Rh, the nitrous oxide-acetylene flame has been used. The results obtained for Zr and W are due to scattering of the laser radiation from unvaporized particles in the flame. Since, for most elements, several fluorescence lines of comparable intensity have been observed after the primary excitation process, the usefulness of observing non-resonance fluorescence is stressed, particularly with regard to the possibility of minimizing spectral interferences. The experimental results demonstrate that the limits of detection obtained with the dye laser source are comparable or better than the best atomic absorption limits only when the same primary absorption line used for the atomic absorption measurements can be used for exciting the fluorescence.     

Two dimensional laser induced fluorescence spectroscopy: a powerful technique for elucidating rovibronic structure in electronic transitions of polyatomic molecules

We demonstrate the power of high resolution, two dimensional laser induced fluorescence (2D-LIF) spectroscopy for observing rovibronic transitions of polyatomic molecules. The technique involves scanning a tunable laser over absorption features in the electronic spectrum while monitoring a segment, in our case 100 cm(-1) wide, of the dispersed fluorescence spectrum. 2D-LIF images separate features that overlap in the usual laser induced fluorescence spectrum. The technique is illustrated by application to the S(1)-S(0) transition in fluorobenzene. Images of room temperature samples show that overlap of rotational contours by sequence band structure is minimized with 2D-LIF allowing a much larger range of rotational transitions to be observed and high precision rotational constants to be extracted. A significant advantage of 2D-LIF imaging is that the rotational contours separate into their constituent branches and these can be targeted to determine the three rotational constants individually. The rotational constants determined are an order of magnitude more precise than those extracted from the analysis of the rotational contour and we find the previously determined values to be in error by as much as 5% [G. H. Kirby, Mol. Phys. 19, 289 (1970)]. Comparison with earlier ab initio calculations of the S(0) and S(1) geometries [I. Pugliesi, N. M. Tonge, and M. C. R. Cockett, J. Chem. Phys. 129, 104303 (2008)] reveals that the CCSD∕6-311G?? and RI-CC2∕def2-TZVPP levels of theory predict the rotational constants, and hence geometries, with comparable accuracy. Two ground state Fermi resonances were identified by the distinctive patterns that such resonances produce in the images. 2D-LIF imaging is demonstrated to be a sensitive method capable of detecting weak spectral features, particularly those that are otherwise hidden beneath stronger bands. The sensitivity is demonstrated by observation of the three isotopomers of fluorobenzene-d(1) in natural abundance in an image taken for a supersonically cooled sample. The ability to separate some of the (13)C isotopomers in natural abundance is also demonstrated. The equipment required to perform 2D-LIF imaging with sufficient resolution to resolve the rotational features of large polyatomics is available from commercial suppliers.     

Two‐Dimensional Spatial Resolution of Concentration Profiles in Catalytic Reactors by Planar Laser‐Induced Fluorescence: NO Reduction over Diesel Oxidation Catalysts

Planar laser‐induced fluorescence (PLIF) enables noninvasive in situ investigations of catalytic flow reactors. The method is based on the selective detection of two‐dimensional absolute concentration maps of conversion‐relevant species in the surrounding gas phase inside a catalytic channel. Exemplarily, the catalytic reduction of NO with hydrogen (2 NO+5 H₂→2 H₂O+2 NH₃) is investigated over a Pt/Al₂O₃ coated diesel oxidation catalyst by NO PLIF inside an optically accessible channel reactor. Quenching‐corrected 2D concentration maps of the NO fluorescence above the catalytic surface are obtained under both, nonreactive and reactive conditions. The impact of varying feed concentration, temperature, and flow velocities on NO concentration profiles are investigated in steady state. The technique presented has a high potential for a better understanding of interactions of mass transfer and surface kinetics in heterogeneously catalyzed gas‐phase reactions.     

Spatially and Temporally Resolved Measurements of NO Adsorption/Desorption over NOx-Storage Catalyst

The two-dimensional (2D) temporal evolution of the NO-concentration over a NOx-storage catalyst is investigated in situ with planar laser-induced fluorescence (PLIF) in an optically accessible parallel wall channel reactor. Signal accumulated phase-correlated 2D-recordings of repetitive adsorption/desorption cycles are obtained by synchronizing the switching of the NO gas flow (on/off) with the laser and detection system, thereby significantly increasing the signal-to-noise ratio. The gas compositions at the reactor outlet are additionally monitored by ex-situ analytics. The impacts of varying feed concentration, temperature and flow velocities are investigated in an unsteady state. Transient kinetics and the mass transfer limitations can be interpreted in terms of the NO concentration gradient changes. The technique presented here is a very useful tool to investigate the interaction between surface kinetics and the surrounding gas flow, especially for transient catalytic processes.     

Development of Laser Ionization Mass Spectrometer for detection of unstable species in flames

Results are presented here on the detection of unstable species formed in flames using a novel Laser Ionization Mass Spectrometry (LIMS) system. The chemical species generated in atmospheric pressure flames were directly introduced into a mass spectrometer operated at high vacuum conditions using a newly developed interface, in which the ionization was induced by laser irradiation. Optimum conditions for the experimental conditions were investigated in order to obtain mass spectra with adequate signal to noise (S/N) ratios. In addition, the distribution profiles of various species in the flame was measured and visualized. The distribution of OH profiles was also measured under the same conditions using Planer Laser Induced Fluorescence (PLIF) diagnostics. The results showed that the profiles of OH distribution by LIMS were in good agreement with those obtained using PLIF diagnostics.     

双燃料发动机缸内分层激光诱导荧光实验及化学动力学模拟研究

双燃料压燃（RCCI）是一种很有前景的发动机新型燃烧方式,能在小负荷到中高负荷范围内实现发动机高效清洁燃烧,为了将RCCI拓展到更高负荷,需要对其缸内燃油分层和燃烧过程开展更深入研究。本文在一台双燃料光学发动机上采用燃油-示踪剂平面激光诱导荧光法（PLIF）,对RCCI着火前缸内燃油分层进行定量测量,选用甲苯作为示踪剂,利用266 nm脉冲激光激发甲苯荧光,发动机转速1200 r·min^-1,平均指示压力6.9×10⁵ Pa,气道喷射异辛烷,缸内在上止点前10°喷射正庚烷。采用燃油-气体绝热混合假设,对PLIF测量结果进行温度不均匀性修正,以上止点后5°曲轴转角下的测量结果为例,不修正相比修正测试区域内的最大当量比高估15%。根据实验结果,利用Chemkin软件分析了活性、浓度和温度分层对燃烧滞燃期的影响,结果显示燃料活性分层和浓度分层共同决定RCCI的着火滞燃期,其中活性分层影响要大于浓度分层,而温度分层对着火滞燃期影响很小。RCCI燃烧过程自发光的高速成像结果表明,着火过程首先出现在燃烧室边缘的高活性区域,随后火焰向燃烧室中心处的低活性区域发展,碳烟辐射光图像显示碳烟主要形成于燃烧室边缘的高活性区域。