基于拉曼光谱的危险液体快速识别研究

快速准确识别不明危险液体在公共安全领域需求明显。拉曼光谱技术因具有快速、灵敏、可非接触式检测等优点,成为近年来此领域的研究热点。以沙林、梭曼、塔崩、维埃克斯、芥子气等化学毒剂,磷酸三甲酯、磷酸三乙酯、磷酸三丁酯、甲基膦酸二甲酯、甲基膦酸二异丙酯等化学毒剂模拟剂,亚磷酸二甲酯、亚磷酸三甲酯、亚磷酸三乙酯、甲基膦酰氯乙酯、甲基膦酰二氯、甲基膦酰二氟、氯沙林、二乙胺基磷酰氯、2-二乙胺基乙硫醇、硫二甘醇、异丙醇、频呐基醇、甲基膦酸、甲基膦酸异丙酯、甲基膦酸频呐基酯等化学毒剂前体、中间产物、水解产物以及有毒工业化学品如邻二甲苯、间二甲苯、苯甲醚、氯代苯、乙酸乙酯、乙酸乙烯酯、乙酸苄酯、甲醇、乙醇、乙腈、丙酮、1,1,1-三氯乙烷、正己烷、正丁醇、四氯化碳等和汽油、水等42种危险液体和常见溶剂为研究对象,使用配备785 nm激光器的便携式拉曼光谱仪,针对上述化合物建立了拉曼光谱检测方法,获得了高信噪比的散射光谱数据,对谱图特征进行了分析。采用线性判别分析（LDA）、二次判别分析（QDA）、k近邻（kNN）、朴素贝叶斯（NB）模型、分类决策树（CT）、支持向量机（SVM）6种模式识别算法对上述拉曼光谱数据进行识别归类。研究结果表明,支持向量机、线性判别分析模型具有100%的识别准确率,考虑到实际使用过程中非标准谱图、仪器条件以及外界环境改变等因素会对支持向量机识别结果产生影响,将线性判别分析模型确定为危险液体的快速识别方法。全部测试过程在1~2 min内即可完成且不损耗样品,成功实现水和危险品汽油与其他有毒液体的区分。该研究揭示了具有指纹谱特征的拉曼光谱结合模式识别算法可用于化合物的快速筛查,为及时发现通关夹带,保证物流安全以及化学恐怖事件应急处置等提供了技术支撑。     

银纳米粒子的SERS效应和SEF效应在微流控芯片光学检测中的应用

银纳米离子的SERS技术和SEF技术的信号检测灵敏度非常高,可以用在微流控芯片的定量分析中。为了提高微流控芯片光学检测技术的检测精度,提出一种在微通道中添加银纳米粒子来增强SYBR GreenⅠ拉曼和荧光信号的方法,并对该方法的原理和增强效果进行了研究。首先,利用准分子激光器在PMMA基板上直写刻蚀出宽200 μm、深68 μm的微通道,接着将制备的银前体溶液加入微通道,通过加热制备出表面增强拉曼（SERS）和表面增强荧光（SEF）基板,接下来对添加银纳米粒子前后的拉曼和荧光信号分别进行对比,进一步研究了微通道中不同浓度银纳米粒子对SYBR GREEN I的拉曼和荧光信号增强效果。添加银纳米粒子后,表面增强拉曼（SERS）实验的增强因子为3.5×10³,添加银纳米粒子的样品的荧光信号强度与不含银纳米粒子样品的荧光信号强度相比,约增加了1倍。结果表明,在微通道中检测SYBR Green I时通过增加银纳米粒子显著地增强了拉曼和荧光信号,这种方法可以用在以SYBR GreenⅠ做染料的微流控芯片检测技术中。     

维生素A酸在银溶胶液中的表面增强拉曼散射光谱

将水中不溶的药物维生素A酸(VAA)溶于氯仿中,然后与银溶胶液混合,振摇,取静置分层后的上层溶胶液测定表面增强拉曼光谱,氯仿在银溶胶中无表面增强效应,不干扰维生素A酸的测定。与固体粉末拉曼光谱相比较,对光谱峰归属进行了解释。通过分析CO伸缩振动带和ν(COO)振动峰明显增强的现象,讨论了维生素A酸分子在银颗粒表面可能的吸附取向,并推断维生素A酸在银表面的吸附发生在COO-基团。以维生素A酸表面增强拉曼光谱在1583cm-1处的峰强度对浓度进行线性回归,求得线性回归方程Y=10×108+95585,在10×10-6～50×10-5mol·L-1范围呈良好的线性关系,最小检测限为10×10-7mol·L-1。结果表明,维生素A酸表面增强拉曼光谱峰数量少,灵敏度高,是定量分析痕量维生素A酸的很好方法。     

TLC-SERS法快速检测改善睡眠类保健食品中四种化学成分

建立薄层色谱(TLC)与表面增强拉曼光谱(SERS)联用技术对改善睡眠类保健食品中四种非法添加化学成分(三唑仑、艾司唑仑、氯硝西泮及奥沙西泮)的快速检测新方法。以环己烷-乙酸乙酯-乙醇(5∶3.5∶2)为展开剂,利用 TLC 将添加成分与保健食品基质初步分离,在UV_{254 nm}下检测定位;以780 nm激光为激发波长,水相银溶胶为表面增强剂,采用SERS法对TLC上的微量添加成分定性检测。通过模拟阳性样品实验,考察保健食品基质对添加成分TLC-SERS的影响,并考察四种化学成分的检测限。建立了改善睡眠类保健品中非法添加四种化学成分的TLC-SERS检测方法。四种添加成分的TLC-SERS与相应对照品的拉曼光谱特征峰存在明显相关性;保健食品的基质对添加成分的检测几乎没有干扰;四种化学成分的检测限为1～4 μg。最后,对市售五种改善睡眠类保健食品进行检测,均不存在非法添加情况。该研究利用TLC与SERS相结合的方法应用于改善睡眠类保健食品中掺杂化学成分的快速检测,并获得了镇静安眠类共四种化药的TLC-SERS谱,建立了改善睡眠类保健食品中非法添加三唑仑等四种化药的检测方法;该法专属、灵敏、快速、简单,并且没有显著的检测时间限制,为改善睡眠类保健食品中掺杂化学成分的现场检测方法研究提供新的参考依据。     

表面增强拉曼光谱检测水中微量的芬太尼

通过化学法合成了具有表面增强拉曼散射(SERS)活性的银胶体,利用透射电子显微镜和紫外可见光谱仪分别对银胶体的形貌和光学性质进行了表征;采用这种衬底对水相中微量的芬太尼进行了SERS检测研究,并对芬太尼的SERS信号进行了归属,考察了各种实验条件对SERS检测的影响。实验结果表明,增大银胶体浓度有利于芬太尼SERS信号的检测;随着团聚剂氯化钠浓度增大芬太尼的SERS信号强度会先增大后减小,即团聚剂浓度存在一个最佳值;在优化的实验条件下芬太尼的检测限可以达到0.1ppm量级。     

胶带快速转移水油液液界面自组装纳米金制备透明柔性SERS基底

表面增强拉曼(SERS)是一种快速灵敏的表面分析检测技术。提出了一种简便快捷的制备高活性的透明柔性SERS基底,使用乙醇诱导Au NPs从水溶液中组装到水/油界面的形成致密的Au MLF后再用透明胶带转移即制备完成了SERS基底。UV-Vis和SEM测试结果显示纳米金被紧密的吸附在透明胶带上。通过调控Au溶胶的浓度以及加入乙醇与Au溶胶的体积比来控制Au纳米粒子在胶带的密度,发现加入的氯金酸体积0.4mL,乙醇与Au溶胶体积比10∶4时,制备完成的Au/Tape基底具有最佳的活性,以孔雀石绿分子为拉曼探针计算了Au/Tape基底的增强因子EF为1.8×107。此基底在非平整表面现场超灵敏快速检测具有潜力。     

Gd~(3+)离子在氨基多膦酸配合物溶液中的敏化发光研究

对 Gd3+离子与氨基多膦酸配体 (乙二胺四亚甲基膦酸和氨三亚甲基膦酸 )配合物溶液荧光的研究表明 ,在碱性溶液中 2种配体可使 Gd3+离子的荧光强度分别增强 9倍和 7.4倍 ,比氨基多羧酸的荧光敏化作用要强得多。其激发和发射峰分别在 2 74 nm和 310 nm,与 Gd3+水合离子相应谱峰的位置相同。表明这种荧光增强来源于氨基多膦酸配体对 Gd3+强烈的配位作用所引起的 f→ f跃迁的部分解禁。由于 Gd-氨基多膦酸配合物十分稳定 ,因此配合物溶液荧光强度基本不受其他共存阴阳离子的影响 ,在一定范围内受 p H值变化的影响也很小。     

表面增强拉曼光谱技术快速检测神经性化学毒剂模拟剂

神经性化学毒剂具有毒性高、挥发性好和作用快等特点,在浓度很低的情况下就可以造成很大的伤亡,因此成为现场快速检测的难点。而化学毒剂沙林（甲氟膦酸异丙酯,GB）是一种经常用的军事神经性毒剂,该毒剂可通过抑制乙酰胆碱酯酶来破坏神经系统的功能,同时该毒剂被吸入后在人体内的降解速度很慢。为了避免和降低该类毒剂的污染和对人员伤害,迫切需要发展一种灵敏度高、准确性好、响应时间短和可便携化的检测技术检测GB。表面增强拉曼光谱(SERS)检测方法具有灵敏度高、操作简单和响应速度快的特点,成为检测水中痕量化学毒剂的有效方法之一。将购买的Ag纳米溶胶进行离心,然后将其组装固定在硅基Au膜表面从而制备高SERS增强的基底来对化学毒剂模拟剂甲基磷酸二甲酯（DMMP）的快速检测方法进行研究。在实验中,通过优化团聚剂的离子强度、测试方法等来对检测条件进行优化筛选。通过对比不同的团聚剂HCl,KI,MgSO₄,NaCl和NaOH,最终得到最优的离子强度,从而确定1 mol·L-1的KI为团聚剂时具有最好的效果。分别对不同的检测方法来进行了相应的优化,通过对比芯片法和液态溶胶法,最终发现改进后的芯片法能够获得较好的检测效果。最终确定的检测方法为将1 mol·L-1的KI和待测溶液（DMMP）混匀,然后滴在事先准备的以Ag纳米溶胶为基质制得的SERS芯片上,用波长为785 nm激光的便携式拉曼光谱仪直接进行检测,最低可以测至10 μg·L-1。而在文献资料中报道美军短期（＜7 d）饮用水最大暴露安全指南规定对神经性化学毒剂最低检出限是10 μg·L-1,因此采用该SERS检测方法,满足了军队应对化学战或者恐怖袭击的行动的需要。实验结果表明该方法突破了便携拉曼光谱仪灵敏度低的局限,解决了痕量神经性毒剂现场快速检测难题,拓展了SERS技术在化学侦察领域的应用。     

高效液相色谱法测定4,4'-双(膦酸二甲酯)甲基联苯

建立了高效液相色谱法测定4,4’-双(膦酸二甲酯)甲基联苯(BPMB)含量的方法.采用Symmetry C18色谱柱(4.6mm×150mm,5μm),流动相为乙腈∶水(40∶60,V/V),流速1.0mL/min;柱温30℃;检测波长252nm.结果表明,BPMB在0.02-0.12mg/mL范围内线性关系良好,相关系数r=0.9996;平均回收率为98.43％;RSD为1.661％(n=6);检出限为4.0μg/L.方法简便、准确度高、重现性好,可用于BPMB含量的测定.     

苋菜红表面增强拉曼光谱的密度泛函理论研究

苋菜红(Amaranth)作为一种人工合成食品添加剂,常被添加于汽水、山楂和糖果等当中,但苋菜红是由煤焦油中分离出来的苯胺染料为原料制成,过量食用会导致基因突变甚至致癌,严重危害身体健康。因此,对其检测至关重要。表面增强拉曼光谱技术具有样品前处理简单、分析速度快和准确性高等优点,已在化学、生物和医学领域越来越显示出巨大的潜能。目前,用拉曼光谱技术对苋菜红检测的理论与实验研究还未见报道。而对拉曼光谱及表面增强理论机理的研究可以为在食品中检测及鉴定苋菜红提供可靠的科学依据。所以利用密度泛函理论全面探究苋菜红的表面增强拉曼机理并与实验结果进行对比,对食品中的苋菜红检测研究有很好的预测及指导意义。一方面,利用共聚焦显微拉曼光谱仪对苋菜红粉末进行拉曼光谱检测,得到其拉曼光谱;另一方面,搭建苋菜红分子结构,并基于密度泛函理论对分子结构进行优化处理,从前线轨道、静电势、极化率及自然键轨道布局分析四个角度进行计算分析,得出偶氮基团处(—N_(15)=N_(16)—)是苋菜红分子与Ag原子配位的最佳位置。在此基础上,使用B3LYP/6-31++G(d, p))基组(C, H, O, N, S, Na)和B3LYP/Sdd基组(Ag)对苋菜红分子与1个Ag原子及3个Ag原子团簇的复合物(Amaranth-Ag_1, Amaranth-Ag_3)进行结构优化和表面增强拉曼光谱计算。将苋菜红分子的实验与理论拉曼光谱进行比较,发现二者吻合较好,且在1 228, 1 329, 1 467和1 529 cm~(-1)处苋菜红分子的拉曼活性很明显。另外,苋菜红与Ag的复合物有明显的拉曼增强效应,增强效果随着Ag原子个数的增多而愈加明显,不仅拉曼光谱的峰值个数有增多,而且其对应光谱峰位强度也有增强。进一步通过振动模式的归属,得到鉴定和识别苋菜红的拉曼特征峰。该研究为利用表面增强拉曼光谱技术检测食品中的苋菜红提供了一定的实验参考和理论依据。     

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.     

Hybrid Wavelength and Code Division Multiple Access in Optical Networks

A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.     

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.     

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.     

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.     

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.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.