胞嘧啶核苷在纳米银膜上的NIR-SERS光谱检测

采用一种高活性的纳米银膜作为表面增强拉曼散射(SERS)基底,以近红外激光(785 nm)作为激发光源,对胞嘧啶核苷(胞苷)水溶液(10-2～10-8 mol·L-1)进行了近红外表面增强拉曼散射(NIR-SERS)光谱检测。实验结果表明,当胞苷水溶液浓度等于或低于10-7 mol · L-1时,可在300～2 000 cm-1范围内获得信噪比较好的NIR-SERS光谱。将胞苷水溶液(10-2～10-5 mol · L-1)分别滴在10片不同的纳米银薄膜上进行检测,结果表明该纳米银膜体现出了较好的光谱重现性。通过对纳米银膜表面形貌进行表征发现聚乙烯醇(PVA)包覆的纳米银颗粒在铝片表面形成“草状”结构。并通过对吸附了胞苷分子的纳米银膜进行紫外-可见光反射光谱检测,发现在800 nm处出现等离子共振峰。因此采用785 nm的近红外激光作为激发光时,该体系能够体现出强烈的表面等离子共振(surface plasmon resonance, SPR)特性。同时采用DFT-B3LYP/6-311G对胞苷分子进行了拉曼光谱计算,计算所采用入射光波长为785 nm,通过计算结果与实验测得的胞苷固体的拉曼光谱对比发现在300～2 000 cm-1范围内两者匹配得较好,进而对其振动进行了归属。最后通过比较胞苷的拉曼光谱和NIR-SERS光谱对胞苷分子在纳米银膜上的可能吸附方式进行了分析。分析结果表明胞苷分子主要为其核糖部分吸附纳米银颗粒上,同时该分子的17NH₂基团可能靠近局域电磁场增强区域。     

2-氨基苯硫酚NIR-SERS光谱及其在纳米银表面吸附行为分析

本文采用静电自组装的方法制备了二维纳米银膜。UV-vis吸收光谱显示其等离子体共振吸收带位于400+900nm的光谱范围,延伸到了近红外区,可以较好的匹配785nm的近红外激发光源。以该纳米银膜为基底,对2-氨基苯硫酚(2-ATP)分子进行了近红外表面增强拉曼散射(NIR-SERS)检测,获得了重复性良好的NIR-SERS光谱图。实验表明:以2-ATP为探针分子时,该纳米银膜的NIR-SERS增强因子达到2.19×109。同时,本文采用密度泛函理论(DFT),以B3LYP/6-31G为基函数,对2-ATP分子进行结构优化和普通拉曼光谱(NR)计算,发现理论值和实验值吻合较好。此外,对2-ATP的NIR-SERS谱带进行了归属分析,发现当2-ATP分子在纳米银表面吸附时,是以-SH基团吸附到银表面,且同时-SH基团会被纳米银氧化。     

恒温法制备纳米银胶及其NIR-SERS活性研究

在恒温条件下(80℃)加热硝酸银和柠檬酸三钠混合液制得纳米银胶。将混合液66mL分别加热60,90,120,150,180和210分钟制得六个不同时间的纳米银胶样本。用紫外-可见(UV-Vis)分光光度计对上述6个样品进行检测,通过UV-Vis吸收光谱分析了纳米银胶中纳米银颗粒的粒径和粒径分布变化情况。同时使用激发光波长为785nm的便携式拉曼光谱仪,以结晶紫(1×10~(-6) mol/L)作为探针分子对加热不同时间的纳米银胶进行近红外表面增强拉曼散射(NIR-SERS)活性研究。最后分析了激光功率和银粒子浓度对结晶紫NIR-SERS光谱的影响。     

基于新型NIR-SERS基底的肝癌血清NIR-SERS光谱研究

基于一种新型、高效、生物兼容性近红外表面增强拉曼散射(NIR-SERS)基底,采用便携式近红外拉曼光谱仪分别对健康人和肝癌病患者的血清进行了NIR-SERS光谱研究.实验发现,健康人与肝癌患者的血清NIR-SERS光谱存在显著差异:1)健康人血清NIR-SERS光谱中位于630、720、812和1578 cm-1附近的...     

巯基乙胺的表面增强拉曼光谱研究

拉曼光谱用于检测物质。但由于物质的普通拉曼信号较弱,因此在微量检测应用中受到限制。本文通过尝试获得了巯基乙胺(C_2H_7NS)粉末、巯基乙胺在纳米银溶胶中的表面增强,巯基乙胺与纳米银粒子在载玻片上自组装纳米银膜的表面增强等的拉曼光谱。应用紫外-可见吸收光谱仪、电子扫描显微镜、电子透射显微镜来对纳米银胶、纳米银膜进行形貌表征。应用Guassian03软件计算出巯基乙胺的拉曼峰,对实验得到的拉曼峰进行对比和归属。对实验得到的拉曼峰比较,巯基乙胺与纳米银粒子在载玻片上自组装纳米银膜获得的表面增强拉曼光谱较好。通过改变巯基乙胺与纳米银粒子在载玻片上自组装时间长短来对该方法进一步优化。     

以PAA为模板制备SERS基底及对三聚氰胺的检测

采用热蒸镀的方法直接在多孔氧化铝(porous anodic alumina,PAA)模板上蒸镀几微米的银膜,然后在HCl溶液中溶解掉模板,得到表面具有纳米尺度规则结构的银膜作为表面增强拉曼散射(surface-en-hanced Raman spectra,SERS)基底,并在该基底上测量了吡啶溶液(0.01 mol.L-1)的增强拉曼光谱,发现平均增强因子大于105。与直接在载玻片上蒸镀的银膜相比,具有纳米尺度规则结构银膜的增强效果提高了30倍。改变激发光功率测量吡啶的拉曼光谱,和普通拉曼散射一样,增强拉曼光谱的峰值强度随激发光强度线性变化,并在该基底上测量了三聚氰胺的拉曼光谱,发现在1 mW的激发功率下对于三聚氰胺的检出限为2.5 mg.L-1。     

D-核糖NIR-SERS光谱及其在金纳米棒表面吸附行为分析

本文采用种子生长法、利用双表面修饰剂制备了金纳米棒,其长径比为3.5:1。该金纳米棒的消光光谱显示:利用该方法制备的金纳米棒有两个表面等离子共振(SPR)峰,分别位于540nm和780nm处。其中780nm处的表面等离子共振峰靠近红外光谱区,可以与文中采用的激发光源(785nm激光)较好的匹配,从而有助于实现共振拉曼散射增强效应。本文以D-核糖(D-Ribose)为探测分子,基于金纳米棒进行了近红外表面拉曼散射(NIR-SERS)活性检测,从而获得了光谱重复性良好的NIR-SERS光谱图。同时,采用密度泛函理论(DFT),以B3LYP/6-31G和6-31G/LanL2DZ为基组函数,分别对D-核糖分子以及D-核糖分子与金原子形成的团簇进行结构优化和普通拉曼光谱(NR)计算,发现理论值和实验值符合较好。此外,文中对D-核糖的NIR-SERS谱带进行了分析和归属,发现当D-核糖分子吸附到金纳米粒棒上时,主要是以羟基上的氧原子(O9)吸附在金原子上而形成金属键。     

Surface Enhanced Raman Scattering on Self-assembled Nano Silver Film Prepared by Electrolysis Method

用一种廉价的电解方法制备了纳米银膜,并详细研究了在这种银膜上的表面增强拉曼散射效果．结晶紫为本实验的检测性分子．通过实验发现,这种银膜用便携式拉曼光谱仪测试并计算出的表面增强拉曼散射的增强因子为603,并对结晶紫的最小检出限为0.1 nmol/L     

以新型银胶为衬底的超低浓度R6G的拉曼光谱检测

利用柠檬酸钠还原硝酸银的原理,提出了一种微波加热制备银胶体粒子的新方法,得到了颗粒大小较均匀的灰色银胶体。以提纯后的银胶为表面增强拉曼散射衬底,研究了超低浓度染料大分子罗丹明6G分子的表面增强拉曼散射,得到浓度分别为10-12mol/L、10-13mol/L和10-14mol/L的罗丹明6G的表面增强拉曼散射光谱,初步实现了罗丹明6G的单分子检测,证明该新型银胶衬底有非常强的表面增强拉曼活性。同时根据表面增强拉曼散射“热点”的增强机理,分析了获得超低浓度R6G的表面增强拉曼光谱的原因。     

纳米银膜的制备及其表面增强拉曼光谱研究

纳米银膜是用硝酸银和聚乙烯醇加入去离子水中作为电解液, 以紫外光激发, 用银棒电解而得到的。扫描电镜被用来具体观测了纳米银的形貌, 发现银膜上的颗粒是紧靠在一起的。我们以结晶紫作为探针分子进行了表面增强拉曼散射效应的的测定, 所用设备为便携式拉曼光谱仪。结果表明光谱的检测限为10-10, 具有很好的增强效果, 这为研究表面增强效应提供了一种新的基底。     

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.     

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.     

A stereo matching algorithm using multi-peak candidate matches and geometric constraints

Gray cross correlation matching technique is adopted to extract candidate matches with gray cross correla- tion coefficients less than some certain range of maximal correlation coefficient called multi-peak candidate matches. Multi-peak candidates are extracted corresponding to three closest feature points at first. The corresponding multi-peak candidate matches are used to construct the model polygon. Correspondence is determined based on the local geometric relations between the three feature points and the multi-peak candidates. The disparity test and the global consistency checkout are applied to eliminate the remaining ambiguous matches that are not removed by the local geometric relational test. Experimental results show that the proposed algorithm is feasible and accurate.