银纳米阵列直径对SERS增强效果的影响

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。     

罗丹明6G在银纳米线阵列上的SERS光谱研究

制备出有序、均匀的活性衬底一直足表面增强拉曼散射(SERS)研究中的关键.阳极氧化法制备的多孔氧化铝膜的结构有序、均匀,为纳米金属SERS基底的制备提供了模板.以沉积了银的多孔氧化铝组装体为衬底,研究了罗丹明6G(Rh6G)分子的表面增强拉曼散射光谱.结果表明,沉积了银的多孔氧化铝模板是很好的SERS衬底,Rh6G分子在此衬底上的SERS谱强度与银纳米线在表面的显露高度有关,而其拉曼频移未受表面状态的影响,而PO43-离子的存在使SERS强度得到很大提高.     

绿色合成银纳米粒子及其在SERS中的应用

采用无毒、绿色的酪氨酸作为还原剂和稳定剂,在碱性条件下还原硝酸银,经60 ℃恒温水浴处理20 min,成功地合成了银纳米粒子。混合溶液颜色由淡黄色变为棕黄色直观地呈现了银纳米粒子的生成。利用紫外可见吸收光谱(UV-Vis)和透射电子显微镜(TEM)对制备样品进行分析和表征。粒子的UV-Vis吸收在412 nm附近。TEM图像显示,银纳米粒子的形状近似球形,粒子直径在15～25 nm。分别以结晶紫(CV)和叶酸(FA)为探测分子,进一步研究了该银纳米粒子的表面增强拉曼散射(SERS)效应。实验结果表明,该合成方法不仅方便、快速、绿色环保,而且合成的银纳米粒子对CV和FA分子有很好的SERS效应。     

银纳米粒子修饰三维碳纳米管阵列SERS实验

为了使表面增强拉曼散射(SERS)基底的三维聚焦体积内包含更多的“热点”,能吸附更多探针分子和金属纳米颗粒,以便获得更强的拉曼光谱信号,提出了银纳米粒子修饰垂直排列的碳纳米管阵列三维复合结构作为SERS基底,并对其进行了实验研究。利用化学气相沉积(CVD)方法制备了垂直排列的碳纳米管阵列;采用磁控溅射镀膜方法先在碳纳米管阵列上形成一层银膜,再通过设置不同的高温退火温度,使不同粒径的银纳米粒子沉积在垂直有序排列碳纳米管阵列的表面和外壁。SEM结果表明：在有序碳纳米管阵列的表面和外壁都均匀地负载了大量银纳米粒子,并且银纳米颗粒的粒径、形貌及颗粒间的间距随退火温度的不同而不同。采用罗丹明6G(R6G)分子作为探针分子,拉曼实验结果表明：R6G浓度越高,拉曼强度越强,但是R6G浓度的增加与拉曼强度增强并不呈线性变化;退火温度为450 ℃,银纳米颗粒平均粒径在100～120 nm左右,退火温度为400 ℃,银纳米颗粒平均粒径在70 nm左右,退火温度为450 ℃的拉曼信号强度优于退火温度400和350 ℃。     

核壳结构CdS/ZnS纳米微粒的制备与光学特性

用微乳液法制备CdS纳米微粒 ,以ZnS对其进行表面修饰 ,得到具有核壳结构的CdS/ZnS纳米微粒 .采用X射线衍射 (XRD)、透射电镜 (TEM )表征其结构、粒度和形貌 ,紫外 可见吸收光谱 (UV)、光致发光光谱(PL)表征其光学特性 .制得的CdS近似呈球形 ,直径为 3.3nm ;以XRD和UV证实了CdS/ZnS核壳结构的实现 .研究了不同ZnS壳层厚度对CdS纳米微粒光学性能的影响 ,UV谱表明随着壳层厚度的增加纳米微粒的吸收带边有轻微的红移 ,同时短波吸收增强 ;PL谱表明壳层ZnS的包覆可减少CdS纳米微粒的表面缺陷 ,带边直接复合发光的几率增大 ,具有合适的壳层厚度时发光效率大大提高 .     

银纳米立方体的合成及其SERS活性研究

用乙二醇还原硝酸银,以聚乙烯吡咯烷酮作表面活性剂合成了银纳米立方体晶粒,并以吡啶和SCN-作为探针分子初步研究了银纳米立方体晶粒组装体系的SERS活性。当探针分子吸附于银纳米立方体晶粒上时,吡啶和SCN-的谱峰强度明显增强,表明银纳米立方体晶粒可望作为SERS活性基底。通过研究探针分子的SERS强度与粒子尺度关系,也有望用于表征银纳米立方体晶粒的光学性质。     

有机溶剂热生长技术制备纳米CdS及其与聚苯胺复合膜的光学性能

以溶剂热生长技术(solvothermal technique)制备了半导体CdS的纳米微粒,并采用XRD、TEM、ED对其结构进行表征。在ITO导电玻璃上,采用电化学方法合成聚苯胺薄膜,以提拉的方法将CdS的纳米颗粒涂布其上,自组装得纳米CdS／PANI膜,并以荧光光谱(PL)及非线性Z-扫描法研究其光学特性。实验结果显示：经CdS修饰后,CdS／PANI膜的荧光发射峰强度增强,位置较单一PANI膜移至420nm处,同时经修饰后的复合物膜的非线性光学特性也有显著的提高。     

激光刻蚀银胶的制备及其SERS应用

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。     

用于SERS基底的Au-Pd核壳纳米颗粒和银纳米立方颗粒的制备及表征(英文)

本文研究了尺寸可控的Au -Pd核壳纳米粒子和银纳米立方颗粒的表面增强拉曼散射(SERS)活性。发现Au-Pd核壳纳米粒子的增强能力要比粗糙的钯电极强;银纳米立方颗粒的增强能力和粗糙的银电极相当。更为重要的是,银纳米立方颗粒既具有原子级平整的小单晶面又处于纳米尺度,因而它们可以作为粗糙表面和结构确定的单晶表面之间的桥梁,对其SERS效应的研究可以加深人们对SERS机理的认识。     

表面增强拉曼散射(SERS)衬底的研究及应用

表面增强拉曼散射(surface enhanced Raman scattering,SERS)是通过吸附在粗糙金属表面或金属纳米结构上的分子与金属表面发生的等离子共振(SPR)相互作用而引起的拉曼散射增强现象,是一种高灵敏的探测界面特性和分子间相互作用的光谱手段。文章归纳总结了近年来常用的SERS衬底的制备方法(溶液中的金属溶胶(MNPs in suspension)、 金属纳米粒子的自组装(self-assembly)、 模板法(Template method)和纳米光刻法(Nanolithographic)等;综述了这些衬底的表面增强拉曼特性;着重介绍了SERS增强在环境监测和生物医学应用上的最新国内外研究动态。目前已经能够实现增强因子高、 可靠性好、 重现性强的SERS衬底的可控制备,表明SERS可以作为一种高性能的分析探测工具,充分实现其潜在应用价值。     

Electrical field analysis of metal‐surface plasmon resonance using a biaxially strained Si substrate

Electrical field components of metal‐surface plasmon resonance were analyzed in detail. Both longitudinal optical (LO) and transverse optical (TO) phonon modes of a biaxially strained Si layer can be excited by surface‐enhanced Raman spectroscopy (SERS). The z to y polarization ratio in SERS measurements was calculated to be 0.78 using the intensity ratio of TO to LO phonon modes. The electrical field components of SERS were also calculated by the finite‐difference time‐domain method. Copyright © 2014 John Wiley & Sons, Ltd.     

Silver nanorods used to promote SERS as a quantitative analytical tool

We have fabricated silver nanorod arrays by electrodepositing the nanorods evenly in the shallow pores of porous anodic aluminum oxide (AAO) templates. The diameter and length were 28 and 44 nm, respectively. The maxima of the transverse and longitudinal modes of the surface plasmon were near 417 and 511 nm, respectively. A good surface‐enhanced Raman scattering (SERS) spectrum was observed by excitation with the 514.5‐nm laser line. The SERS intensity increased almost linearly upon malachite green isothiocyanate adsorption on the tips of the silver nanorods as the concentration of the mother solutions increased. Our results show that silver nanorods fabricated on AAO templates could be used as an SERS substrate for quantitative analyses. Copyright © 2009 John Wiley & Sons, Ltd.     

Optical characterization of CdS semiconductor nanoparticles capped with starch

Starch capped cadmium sulfide (CdS) nanoparticles were synthesized by aqueous solution precipitation. Starch added during the synthesis of nanoparticles resulted in cadmium-rich nanoparticles forming a stable complex with starch. The size of the CdS quantum dots was measured using high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). The average diameter (d) of nanoparticles spanned the range 4.8 ± 0.4 to 5.7 ± 0.2 nm when the pH of the solution was varied within the range 10-14. The main Raman phonon of CdS, the longitudinal optical mode located around 300 cm⁻¹, softens as diameter decreases, in accordance with theoretical predictions. In addition, the largest Raman response of starch, near 478 cm⁻¹, related with the important skeletal vibration modes of the starch pyranose ring, dominates the spectra of the CdS capped nanoparticles and also softens as the size decreases. This fact indicates a strain variation on CdS as a function of d which increases as the pH increases.     

Application of calixarene to high active surface‐enhanced Raman scattering (SERS) substrates suitable for in situ detection of polycyclic aromatic hydrocarbons (PAHs) in seawater

The characteristics of the sol–gel matrix embedding Ag nanoparticles functionalized with 25,27‐dimercaptoacetic acid‐26,28‐dihydroxy‐4‐tert‐butylcalix[4]arene (DMCX) suitable for the in situ detection of polycyclic aromatic hydrocarbons (PAHs) in seawater is presented. The DMCX‐functionalized silver nanoparticles were produced by the thermal reduction method in xerogel film. The silver colloid blocks were formed in the sol–gel matrix, with a diameter ranging from 50 to 120 nm. DMCX forming the monolayer on the silver nanoparticle surface contributes to the surface‐enhanced Raman scattering (SERS) activity due to the aggregation of silver nanoparticles and the preconcentration of PAH molecules within the zone of electromagnetic enhancement. When selected, PAH molecules e.g. pyrene and naphthalene were adsorbed onto the SERS substrate; Raman band positions of PAH were slightly shifted. A calibration procedure reveals that this type of SERS substrate has a limit of detection of 3 × 10⁻¹⁰ mol/l for pyrene and 13 × 10⁻⁹ mol/l for naphthalene in artificial seawater. The Raman signal response on a pyrene concentration change in artificial seawater was evaluated using a 671‐nm Raman setup with a flow‐through cell. This type of SERS substrate will be suitable for the in situ trace detection of pollutant chemicals in seawater. Copyright © 2012 John Wiley & Sons, Ltd.     

785 nm激光诱导银纳米三角片聚集表面增强拉曼散射效应

为实现表面增强拉曼散射（SERS）光谱的强信号快速检测分析,报道了通过785 nm激光诱导银纳米三角片（AgNPRs）聚集的方法。采用配体辅助化学还原法制备了AgNPRs,其边长约为80 nm,表面等离子体吸收峰出现在约774 nm处,对785 nm光产生有效吸收。在785 nm光辐照下,AgNPRs逐渐聚集,对巯基苯甲酸的SERS信号逐渐增强,其源于AgNPRs吸收的光转化为热而引起的AgNPRs聚集。其增强因子高达10⁹。为快速获得强SERS信号,激发光功率需大于250 mW。     

Size‐dependent Raman and infrared studies of PbSe nanoparticles

Micro‐probe Raman and far‐infrared absorption spectroscopies were used to prove the existence of optical phonon modes of PbSe nanoparticles prepared by colloidal chemistry and preliminarily characterized by transmission electron microscopy. To the best of our knowledge, this is the first time that evidence of the surface phonon (SP) mode by Raman spectroscopy has been experimentally observed. The wavenumber of the SP mode is consistent with its prediction by a dielectric continuum model. While for different PbSe nanoparticle sizes the observed SP mode does not show any obvious change in its position, there is a clear shift by approximately 4 cm⁻¹ toward higher wavenumber in the appearance of the LO(Γ) in the Raman spectra from the 3 nm to the 7 nm PbSe nanoparticles. Far‐infrared measurements demonstrate the presence of the transverse optical TO(Γ) and of the coupled phonon modes. Copyright © 2008 John Wiley & Sons, Ltd.     

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。     

Surface‐enhanced Raman scattering and density functional theory studies of bis(4‐aminophenyl)sulfone

Raman and surface‐enhanced Raman scattering (SERS) spectra of dapsone by using colloidal silver nanoparticles have been recorded. Density functional theory was used for the optimization of ground state geometries and simulation of the vibrational spectrum of this molecule. The SERS spectrum with a large silver cluster as a model metallic surface was simulated for the first time. Taking into account the experimental and calculated Raman as well as the SERS normal modes and the corresponding assignments, along with the modeling of the free dapsone and the one in the presence of the colloidal silver nanoparticles, the importance of the sulfone group on the SERS effect in dapsone was inferred. Copyright © 2009 John Wiley & Sons, Ltd.     

Amplification of raman scattering by localized plasmons in silver nanoparticles on the surface of zinc oxide nanorods

The magnetron sputtering of Ag nanoparticles onto ZnO nanorod arrays is studied. The lateral faces of the nanorods are coated with nanoparticles at a much lower density as compared to the flat faces at comparable sputtering times. The silver density is high on the edges of the lateral faces of the nanorods. The plasmon absorption in the synthesized arrays of nanorods coated with individual Ag nanoparticles is maximal at 450?C500 nm. The appearance of local plasmon excitations increases the intensity of the multiphonon processes with the participation of ZnO polar modes in Raman spectra. The cross section of resonance Raman scattering for A ₁(LO) phonon overtones increases with the equivalent Ag film thickness.