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1.
张星  郝艳玲  方炎 《光散射学报》2013,25(3):250-254
研究了温度对皮考酸(2-吡啶羧酸)分子在银胶体系中表面增强拉曼散射(SERS)谱的影响。变温范围在22℃~80℃时,皮考酸吸附在银纳米颗粒表面的SERS谱是可逆的,说明银胶体系在此温度范围内是一种稳定的SERS活性基底。银胶与皮考酸的混合液在持续加热的过程中,SERS谱的整体强度增强,但各谱峰的相对强度变化不大,分析认为在22℃~80℃范围内,皮考酸分子在银纳米颗粒表面的吸附方式基本不变,一直以羧基和N原子上的孤对电子共同作用侧立吸附在银纳米颗粒表面,文中还解释了SERS强度整体增强的原因。  相似文献   

2.
表面增强拉曼散射(SERS)很大程度的弥补了拉曼散射强度弱的缺点,迅速成为科研工作者们的研究热点,在食品安全、环境污染、毒品以及爆炸物检测等领域应用广泛。纳米技术的发展使得目前对于SERS的研究主要集中于金属纳米颗粒基底的制备,金属纳米粒子的种类、尺寸及形貌对SERS增强和吸收峰峰位均有影响,要获得好的增强效果,需要对金属纳米结构进行工艺优化。特别是,需要结合金属纳米粒子的结构和激励光波长,以期获得更好的增强效果。为了研究SERS增强和吸收峰之间的关系,开展了具有双共振吸收峰的金属纳米粒子的研究。首先利用FDTD Solutions仿真建模,主要针对金纳米颗粒直径、金纳米棒长径比及分布状态对共振吸收峰进行仿真,得到金纳米球理论直径在50 nm左右,金纳米棒理论长径比在3.5~4.5左右时,吸收峰分别分布在532及785 nm附近,符合多波段激励光拉曼增强条件;对于激励光偏振方向,其沿金纳米棒长轴方向偏振时吸收峰位于785 nm附近,沿金纳米球短轴方向偏振时吸收峰位于532 nm附近。然后采用种子生长法,制备了可用于多种波长激励光的双吸收峰表面增强拉曼散射基底。通过改变硝酸银用量(5,10,20,30和40 μL)、盐酸用量(0.1和0.2 mL)以及其生长时间(15,17,21和23 h)等多种工艺参数来控制金纳米棒含量,得到了同时含有金纳米球及金纳米棒的双吸收共振峰金纳米粒子。最后用该样品作为基底,罗丹明6G(R6G)作为探针分子,分别测试其在532,633和785 nm激励光入射时的SERS表征,对分析物R6G最低检测浓度均达到了10-7 mol·L-1,增强因子达到了~105,满足了多波段SERS检测的需要。  相似文献   

3.
将一定量的十六烷基三甲基溴化铵溶于500mL去离子水中作为电解液,用直径为1.0cm、长为10.0cm银棒分别作为阴及阳电极,加上7V直流电压,通电3h,用电解方法得到了乳白色的纳米溴化银溶胶。用吸收光谱、对该进行研究。其吸收峰为292.5nm,透射式电镜表明纳米溴化银粒径分布在一个较大的范围,既有大小不一的球形粒子,也有大小不一的椭球形粒子,部分粒子产生了凝聚。为测试该纳米溴化银溶胶是否具有表面增强拉曼散射(SERS)活性,选用了阳离子型分子甲基橙(Methylorange)、中性分子苏丹红(Sudanred)及吡啶(Pyridine)作为测试分子,用二次去离子水配成适当浓度后,与纳米溴化银溶胶按1∶1的比例混合后,置入毛细管样品池中用Renishaw2000测定,激发波长514.5nm。结果发现电解法制备的纳米溴化银对这三种分子都具有较强的SERS活性,甲基橙中明显增强的峰是1123,1146,1392,1448,1594cm-1;苏丹红中明显增强的峰是1141,1179,1433,1590cm-1;吡啶中明显增强的峰是1003,1034,1121cm-1。值得注意的是在该方法制备的纳米溴化银上,得到了在常规方法制备的黄银胶、灰银胶上得不到的甲基橙分子的SERS谱,对可能的原因进行了讨论。  相似文献   

4.
以柠檬酸钠同时还原制备的Ag-Au合金纳米粒子为种子,用盐酸羟胺进一步使其生长得到粒径为40~60nm的新型Ag-Au合金纳米粒子,采用UV-Vis光谱和TEM对纳米种子和再生长后的纳米粒子分别进行表征.两种粒子的UV-Vis光谱均只观察到一个等离子体共振峰,其频率随金的摩尔分数(XAu)增加而红移,且TEM图像表明这两种粒子的颜色均一,因此判断这两种粒子均为合金结构.以苯硫酚为探针分子,研究了该新型合金纳米粒子的表面增强拉曼光谱(SERS),结果表明吸附了苯硫酚的合金纳米粒子的紫外最大吸收峰红移,并在近红外区出现聚集体的吸收峰.在632.8 nm波长激发下,由于表面等离子体共振效应Au上的SERS信号最强,而合金纳米粒子上的SERS信号随XAu增大而增强.  相似文献   

5.
以多孔阳极氧化铝(porous anodic alumina,PAA)膜为模板,采用真空电子束蒸镀技术,分别在PAA多孔层以及阻挡层表面形成了银纳米孔和银纳米帽有序阵列表面增强拉曼散射(surface-enhancedRaman scattering,SERS)活性基底,并以膀胱肿瘤细胞作为分子探针,测试和分析了这两种SERS活性基底的表面增强拉曼光谱的特性。结果表明,两种SERS活性基底对膀胱肿瘤细胞的拉曼散射信号均有很好的增强作用。银纳米帽有序阵列SERS活性基底不仅具有较高的SERS增强和荧光猝灭效应,而且不存在与PAA膜中草酸根杂质相关的干扰峰,可获得膀胱肿瘤细胞拉曼散射光谱的更多细节信息。  相似文献   

6.
激光刻蚀银胶的制备及其SERS应用   总被引:5,自引:4,他引:1  
激光刻蚀技术制备金属胶体是一种新兴的表面增强拉曼散射(SERS)活性衬底制备方法,本文利用激光刻蚀技术制备了'化学纯'银胶,并通过透射电镜、吸收光谱、表面增强拉曼散射光谱等手段对其进行研究,结果表明:银胶的等离子体共振吸收峰位于396nm;银粒子分布比较均匀,多数为球形颗粒,颗粒大小在20nm左右,并且有很好的分散性;吡啶的SERS谱分析显示此银胶具有很好的增强效果。  相似文献   

7.
具有"热点"结构的有序纳米图案由于其高灵敏度和高重复性可以作为表面增强拉曼散射(SERS)基底。基于多级周期阳极氧化铝模板独特的三维孔道,以聚合物复制其多级结构,得到具有一定长径比的纳米棒阵列,并蒸镀贵金属银获得SERS活性。通过精确调控多级周期纳米棒阵列周期内和周期间纳米棒的间距,使纳米棒在等离子体驱动过程中以周期为单位转变为"闭合"状态,从而实现动态响应过程并获得高效SERS活性位点。该动态响应基底有望进一步发展为智能等离激元器件。  相似文献   

8.
将硝酸银和聚乙烯醇加入去离子水中混合后作为电解液,以紫外光激发,用银棒电解得到纳米银膜。用扫描电镜观测纳米银的形貌,发现银膜上的颗粒是紧靠在一起的。以该纳米银膜为基底,用便携式拉曼光谱仪对4个正常人和7个白血病人的血红细胞样品进行了表面增强拉曼散射(SERS)光谱的检测。实验中发现,该纳米银膜对人血红细胞的拉曼散射光谱具有较好的增强的效果和较好的重复性。比较正常人与白血病人血红细胞的SERS谱,存在明显的差别,7个白血病人血红细胞样品在1385 cm-1(吡咯四分之一环伸缩振动)处SERS峰消失,在1425 cm-1处的谱线(CαCm的对称伸缩振动)变宽和变强,对可能的原因进行了分析。  相似文献   

9.
报道了一种新的制备SERS基底的方法。通过对全息干版进行曝光、显影和定影,获得了具有良好稳定性的固体银膜。用紫外-可见光谱测量其表面等离子体共振吸收,发现其吸收谱线在420nm处存在银粒子的特征吸收峰,且吸收峰具有较窄的半峰宽,这表明采用该方法制备的银膜表面分布着大小均一的银粒子。用扫描电子显微镜对其表面粒子形貌进行表征,发现银粒子分布均匀且平均粒径为100nm左右。同时以结晶紫为探针分子测量了该银膜的表面增强拉曼光谱,结果表明该银膜具有良好的表面增强拉曼散射活性。采用这种方法制备的银膜稳定性好且易于保存,在常温下空气中放置数月,仍能保持原有的表面增强拉曼散射活性。  相似文献   

10.
采用电化学沉积法分别在不同孔径的阳极氧化铝(AAO)模板上沉积一系列直径不同,排列规则的银纳米阵列。以对氨基苯甲酸(PABA)和三聚氰胺两种分子分别作为探针分子, 研究了银纳米阵列的直径大小对其表面增强拉曼散射(SERS)效果的影响。结果表明, 在波长为514.5 nm的激光激发下, 探针分子的SERS信号强度随银纳米阵列直径的改变而明显变化, 并在银纳米阵列直径约为53 nm时, SERS强度达到最大。利用电磁增强机制对此实验结果进行了分析和解释。  相似文献   

11.
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.  相似文献   

12.
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.  相似文献   

13.
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.  相似文献   

14.
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.  相似文献   

15.
16.
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.  相似文献   

17.
A transient suppression method for piezoelectric ceramic transducer is presented. By adding some special pedestal pulses to the original transmitted signal, the transient effects in the output of the transducer can be just precisely transmission by use of a narrowband transducer. canceled, thereby achieving the broadband The experimental results show that the transient responses of the sinusoid pulses and coded signals are suppressed successfully and the acoustic waveforms radiated into the surrounding water are improved significantly.  相似文献   

18.
We experimentally demonstrate amplitude squeezed soliton utilizing intensity-dependent self-phase modulation in an asymmetric Sagnac interferometer.The system.whose components are connected via ferrule connector/physical connection(FC/PC)fiber connectors,constitutes all-fiber configuration to generate squeezed soliton.Soliton amplitude reduction measured by homodyne detection is near 4.0 dB below the shot-noise level.Optimal squeezing fields in both simple and compact all-fiber configuration are obtained.  相似文献   

19.
The(2 1)-dimensional nonlinear Schr(o)dinger(NLS)equation with spatially inhomogeneous nonlinearities is investigated,which describes propagation of light in(2 1)-dimensional nonlinear optical media with inhomogeneous nonlinearities.New types of optical modes and nonlinear effects in optical media are presented numerically.The results reveal that the regular split of beam can be obtained in (2 1)-dimensional nonlinear optical media with inhomogeneous nonlinearities,by adjusting the guiding parameter.Furthermore,the stability of beam regular split is discussed numerically,and the results reveal that the beam regular split is stable to the finite initial perturbations.  相似文献   

20.
In the real-world application of face recognition system, owing to the difficulties of collecting samples or storage space of systems, only one sample image per person is stored in the system, which is so-called one sample per person problem. Moreover, pose and illumination have impact on recognition performance. We propose a novel pose and illumination robust algorithm for face recognition with a single training image per person to solve the above limitations. Experimental results show that the proposed algorithm is an efficient and practical approach for face recognition.  相似文献   

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