SnO2纳米粒子作为SERS基底的研究

采用溶胶-水热法制备了不同尺寸的SnO2纳米粒子, 并将其作为表面增强拉曼散射(Surface-enhanced Raman scattering, SERS)活性基底, 重点探讨了表面缺陷能级与SERS性能的关系. 观察到4-巯基苯甲酸(4-MBA)吸附在150 ℃水热合成的SnO2纳米粒子上的SERS 信号最强, 随着在空气中煅烧温度的升高, SERS信号逐渐减弱. 分别用透射电子显微镜、 紫外-可见光谱、 荧光光谱、 X射线衍射和X射线光电子能谱对SnO2纳米粒子进行了表征. 结果表明, SnO2纳米粒子的表面氧空位和缺陷等表面性质在增强拉曼散射性能中发挥着重要的作用, 表面氧空位和缺陷等含量越高其SERS信号就越强.     

纳米TiO2的光致发光性能与SERS效应的关系

以采用溶胶-水热法制备的纯TiO₂及Zn掺杂的TiO₂纳米粒子作为SERS活性基底, 研究了其光致发光机制及其与表面增强拉曼散射(SERS)性能的关系. 结果表明, TiO₂纳米粒子的表面缺陷和氧空位等表面性质在其光致发光和增强拉曼散射性能中发挥着重要的作用. 在表面缺陷和氧空位含量较低时, TiO₂纳米粒子的光致发光光谱(PL)信号越强, 其SERS性能就越高; 当TiO₂纳米粒子的表面缺陷和氧空位含量达到一定程度时, TiO₂纳米粒子的PL信号越弱, 其SERS性能越高.     

A new surface-enhanced Raman scattering system for carbon nanotubes

A new surface-enhanced Raman scattering (SERS) system of carbon nanotubes (CNTs) is reported for the first time. According to the remarkable mechanical property, CNTs were grinded on a sheet of silver directly. Thus rough silver surface was obtained, at the same time, the CNTs attached to the rough silver surface. High quality SERS spectra were obtained from CNTs attached to the rough silver surface. Because there were no solvents affecting the SERS of CNTs, the dependability of the result is improved. The theory and experiment results indicate that this is an accurate and practicable method for SERS study of CNTs.     

A new substrate for surface enhanced Raman scattering of dye Sudan molecules

A new SERS substrate was prepared using electro-polishing aluminum foils. Based on these high active SERS systems, surface enhanced Raman scattering (SERS) of Azo Dye Sudan were performed and carefully studied based on this highly active SERS substrate. High quality SERS spectra were obtained, which indicates that this kind of coarse aluminum foils is an active SERS substrate. Numbers of additional modes were presented, as well as some split peaks, which may be a consequence of symmetry lowering.     

Porous GaN as a template to produce surface-enhanced Raman scattering-active surfaces

Surface-enhanced Raman spectroscopy (SERS) substrates have been prepared by depositing Au or Ag on porous GaN (PGaN). The PGaN used as the template for the metal deposition in these studies was generated by a Pt-assisted electroless etching technique. PGaN was chosen as a potential SERS template due to its nanostructured surface and high surface area, two characteristics that are important for SERS substrates. Metal films were deposited either by solution-based electroless deposition or by thermal vacuum evaporation. SERS spectra were recorded at lambda = 752.5 nm for Au films and at lambda = 514.5 nm for Ag films deposited on PGaN. The SERS signal strength across the metal coated PGaN substrates was uniform and was not plagued by "hot" or "cold" spots on the surface, a common problem with other SERS surfaces. The Ag film deposited by electroless deposition had the highest overall SERS response, with an enhancement factor (EF) relative to normal Raman spectroscopy of 10(8). A portion of the increase in EF relative to typical SERS-active substrates can be assigned to the large surface area characteristic of the PGaN-Ag structures, but some of the enhancement is intrinsic and is likely related to the specific morphology of the metal-nanopore composite structure.     

金银合金纳米粒子表面处理及其表面增强拉曼光谱研究

采用水合肼还原的方法制备了金银比例为1∶1的金银合金纳米粒子, 紫外可见吸收光谱显示合成的溶胶只有一个介于金和银之间的吸收峰, 证明了合金结构的形成. 通过氨基耦联方法将合金纳米粒子组装到硅片表面, 利用氯金酸与合金中银的反应对基底上合金纳米粒子表面进行了改性处理. 以吡啶为探针分子, 研究了表面处理前后基底的SERS效应的差别, 结果表明随着浸泡时间延长, 信号强度先逐渐增强后降低至不变, 这与合金纳米粒子表面结构的变化有关, 氯金酸与表面银的反应经历了两个过程, 即粒子表面形成小的孔洞(去合金过程)和AgCl(s)在粒子表面的沉积, 前者有利于SERS效应的提高, 而后者导致SERS效应快速衰减.     

Extreme red shifted SERS nanotags

Surfaced enhanced Raman scattering (SERS) nanotags operating with 1280 nm excitation were constructed from reporter molecules selected from a library of 14 chalcogenopyrylium dyes containing phenyl, 2-thienyl, and 2-selenophenyl substituents and a surface of hollow gold nanoshells (HGNs). These 1280 SERS nanotags are unique as they have multiple chalcogen atoms available which allow them to adsorb strongly onto the gold surface of the HGN thus producing exceptional SERS signals at this long excitation wavelength. Picomolar limits of detection (LOD) were observed and individual reporters of the library were identified by principal component analysis and classified according to their unique structure and SERS spectra.     

Optimization of the preparation of glass-coated, dye-tagged metal nanoparticles as SERS substrates

Dye-tagged metal nanoparticles are of significant interest in SERS-based sensitive detection applications. Coating these particles in glass results in an inert spectral tag that can be used in applications such as flow cytometry with significant multiplexing potential. Maximizing the SERS signal obtainable from these particles requires care in partitioning available nanoparticle surface area (binding sites) between the SERS dyes and the functionalized silanes necessary for anchoring the glass coating. In this article, we use the metal-mediated fluorescence quenching of SERS dyes to measure surface areas occupied by both dyes and silanes and thus examine SERS intensities as a function of both dye and silane loading. Notably, we find that increased surface occupation by silane increases the aggregative power of added dye but that decreasing the silane coverage allows a greater surface concentration of dye. Both effects increase the SERS intensity, but obtaining the optimum SERS intensity will require balancing aggregation against surface dye concentration.     

吡啶在几种金属纳米线阵列上的表面增强喇曼光谱

近20多年来利用表面增强喇曼光谱（SERS）的研究还仅限于Ag,Au,Cu这三种具有强SERS效应的金属,最近,田中群等利用合适的表面处理方法和共焦曼光谱技术成功地获得了许多无机离子和有机小分子吸附在一系列的过渡金属（如Pt,Ni,Fe,Pd,Rh,Co,Ru等）上的SERS光谱,拓宽了SERS的应用范围,但这些表面处理方法对基底进行处理时存在着较大的随机性,从而导致对所得SERS信号的解释困难。近年来通过自组装膜、模板合成等技术可得比较有序具有强SERS效应的或表面,例如Nie等最近发现尺寸分布狭窄的Ag溶胶粒子（约80－100nm）能诱导出巨大的SERS增强;Freeman和C tffumj m jf rbutb uqf At A 体微粒组装在聚合物基底上,制得高活性的SERS基底,以上工作都表明制备有序纳米级金属颗粒表面将推动SERS的应用和机理研究,迄今,3半导体纳米线阵列上的喇曼光谱已有报道,而利用金属纳米线阵列作为SERS基底除半于样模合成法制备的Ag纳米线阵列上的SERS之外,尚未见其它相关报道,本文主要研究样模合成法制备金属纳米线的过程,并以此为基底研究吡啶吸附的SERS光谱。     

Clean and modified substrates for direct detection of living cells by surface-enhanced Raman spectroscopy

Iodide adsorption and electrochemical negative potential desorption were proposed and compared to obtain clean SERS substrates. The two methods can effectively eliminate the interference of surface impurities in the SERS detection. SERS signals of membranes of living cells with a good reproducibility have been obtained.     

等离激元激励表面增强拉曼光谱检测技术与仪器

本文总结了近年来基于传播型表面等离激元（Propagafingsurfaceplasmons,PSPs）参与的表面增强拉曼（Surface—enhancedRamanscattering,SERS）技术和仪器方面的研究进展．内容主要包括3部分：（1）基于PSPs激励拉曼散射的装置和技术,包括在消逝场下激发PSPs共振增强拉曼的原理与装置、与表面等离子体共振（Surfaceplasmonresonance,SPR）传感技术的联用及新型结构的长程等离激元激励拉曼技术的研究进展;（2）通过引入局域型表面等离激元（Localizedsurfaceplasmons,LSPs）进一步增强SERS,进而实现PSPs-LSPs共同增强拉曼的超灵敏检测技术,包括在消逝场激发的PSPs基础上,增加纳米粒子实现的PSPs与LSPs共同增强拉曼的原理、装置,以及用该方法进行生物体系的免疫识别检测,此外,还在微纳周期结构上实现了PSPs与LSPs共同激励拉曼;（3）基于PSPs耦合的定向SERS技术,包括在消逝场结构和周期结构上实现SERS定向耦合发射以达到高激发和高收集效率的新技术．     

Role of O2 in inducing intensive fluctuations of surface-enhanced Raman scattering spectra

Confocal Raman microscopic measurements were performed on silver electrodes covered with hydrogenated amorphous carbon (a-C:H). When short accumulation time was used, the subsequently measured surface-enhanced Raman scattering (SERS) spectra exhibited fluctuations. As previously reported for other systems, the intensity of fluctuations of SERS spectra significantly decreases if O2 was removed from the ambient medium. In this contribution we show that intensive SERS fluctuations can be also observed for a-C:H/Ag samples immersed in the deoxygenated electrolyte after applying a negative potential pulse to the silver electrode. It means that the O2-mediated Burstein mechanism of SERS fluctuations, which has been previously proposed to explain the SERS O2 effect, is not adequate for these results. We suggest that oxygen chemisorbed on the silver surface decreases the average strength of the interaction between a-C:H clusters and the metal surface (and hence the speed of movement of a-C:H clusters across the metal surface) and that the SERS O2 effect should be rather explained using the "classical" model of SERS fluctuations, in which fluctuations are interpreted as a result of the thermally activated diffusion of carbon segments in and out of the SERS "hot spots". A numerical algorithm for modeling of the fluctuations of SERS intensity has been proposed, and some example simulations of SERS fluctuations have been carried out. For the first time, strongly fluctuating bands due to the stretching vibrations of significantly weakened C-H bonds have been identified.     

银电极表面异亮氨酸单分子膜结构和表面性质的表面增强拉曼光谱研究

利用表面增强拉曼光谱(SERS)技术研究了在粗糙化银电极表面吸附的异亮氨酸自组装单层膜结构及其表面性质随溶液酸碱性和电极电位改变的特征.研究结果表明溶液pH值的变化并没有显著改变异亮氨酸分子在银电极表面以去质子化羧基吸附为主的特征.借助于高氯酸根离子这一SERS光谱探针,对异亮氨酸单分子膜的表面酸碱性质进行了表征和分析.而就电位改变对该单分子膜结构的影响而言,在所研究的电位范围内,单分子膜中的异亮氨酸分子是通过去质子化羧基与氨基两个位点而吸附的,且吸附作用随电位负移而呈现有规律的变化.     

Effect of silver nanowires on the surface-enhanced Raman spectra (SERS) of the RNA bases

RNA bases have a great importance in the biological and genetics applications. The surface-enhanced Raman scattering (SERS) was used to study the orientation and adsorption structure of RNA bases adsorbed on the surface of silver nanowires (Ag NWs). The Ag NWs were prepared and its UV-vis spectra were recorded. The RNA bases oriented perpendicularly on the surface of Ag NWs, as the coverage area decreases. Consequently, the in-plane bands were enhanced according to the SERS selection rule. Many bands were red shifted due to the chemisorption of RNA bases on the Ag NWs surface. New bands corresponding to the base-surface bond were appeared in the SERS spectra.     

单粒子表面增强拉曼光谱的二维成像研究

以单个椭球形Fe₂O₃@Au核壳粒子作为SERS活性基底, 苯硫酚(TP)作为探针分子, 研究了椭球形粒子表面SERS效应的分布, 对比了粒子尖端以及中间SERS效应的差别. 为了得到单个粒子表面不同部分对SERS强度的贡献差别, 通过数学模拟和解析了探针分子SERS的二维成像(2D-mapping)信号, 获得了粒子边缘不同点的SERS效应. 模拟分析结果表明, 当xy平面内粒子在垂直入射(z轴)平面波作用下, 单个椭球形Fe₂O₃@Au核壳粒子表面单位面积上的SERS强度相差极大, 粒子长轴方向端点附近单位面积上的SERS效应最大, 而其它表面部分较弱, 其中与短轴平行方向的表面附近为最弱, 差异可达到约2~3个数量级. 若考虑SERS增强主要为电磁场增强的尖端效应, 则单个椭球形粒子尖端的局域感应电磁场为垂直方向的5倍.     

Effects of underpotentially deposited TI and Pb submonolayers on the surface-enhanced Raman scattering (SERS) from pyridine at Ag electrodes

SERS from pyridine on an Ag electrode is almost completely quenched by underpotential deposition of TI to a surface coverage of ≈ 3%. Removal of TI by anodic stripping does not restore the original SERS intensity. These results suggest that only a small fraction of adsorbed pyridine molecules is SERS active, and TI is specifically deposited on such a SERS active site, which then undergoes irreversible destruction. Pb appears to be non-specifically deposited on the Ag surface, but exhibits a similar irreversible quenching of SERS.     

电化学表面增强拉曼光谱—现状和展望

许多和能源、生命相关的过程都强烈依赖于电化学荷电界面的结构和性能.自从表面增强拉曼光谱效应发现后,就很快地被应用于电化学界面的原位研究,即从分子水平上深入表征各种表面(或界面)的结构和过程,如鉴别物种在表面的键合、构型和取向等.最近十年,纳米科技的飞速发展为SERS技术提供了丰富的基底以及检测和表征方法,从而推动了与纳米科学密切相关的电化学SERS领域令人瞩目的发展.本文系统介绍Au和Ag的SERS、过渡金属薄层SERS、纯过渡金属SERS、核壳结构SERS和已经可以应用于单晶表面研究的gap-modeSERS、TERS和SHINERS,其中穿插着介绍电化学SERS的历史发展、现状和存在的问题及其展望,为电化学SERS研究提供较为全面的详细的参考.     

表面增强拉曼散射活性基底

表面增强拉曼散射(SERS)是人们将激光拉曼光谱应用到表面科学研究中所发现的异常表面光学现象。它可以将吸附在材料表面的分子的拉曼信号放大106到1014倍,这使其在探测器的应用和单分子检测方面有着巨大的发展潜力。由于分子所吸附的基底表面形态是SERS效应能否发生和SERS信号强弱的重要影响因素,所以分子的承载基体是很关键的,因而SERS活性基底的研究一直是该领域的研究热点之一。本文总结了形态各异的表面增强拉曼散射活性基底,分析了最新发展并对其未来作一展望。     

Distance‐dependent Enhancement in Raman Spectroscopy Probed by Conjugated Molecules with Different Molecular Lengths

In this study, the distance‐dependent enhancement effect in surface‐enhanced Raman scattering (SERS) was explored with molecules bearing different lengths of conjugated double bonds. These conjugated molecules were synthesized utilizing the diazotization‐coupling reaction allowing a thio group on one end and a nitro group on the other end. The thiol group allows the probed molecule to chemisorb on the surface of silver nanoparticles (AgNPs). The opposite end of each molecule contains a nitro group, which gives an intense SERS signal to show a fair and accurate comparison of the effect of chain length. The obtained SERS intensities were correlated with the chain lengths of these synthesized molecules, which ranged from 0.6 to 2.0 nm between the nitro and thiol groups. Based on these results, the electromagnetic field effect was mainly responsible for the signal enhancements in SERS measurements. Also, the obtained signals were exponentially decayed due to the distances of the surface of AgNPs. Based on the SERS intensities of the conjugated molecules, the contribution of CT effect to SERS for these examined molecules were limited.     

Detection of volatile organic compounds using surface enhanced Raman spectroscopy substrates mounted on a thermoelectric cooler

Preliminary results for a volatile organic compound (VOC) sensor based on surface enhanced Raman spectroscopy (SERS) are described. The sensor is comprised of a SERS substrate mounted on a thermoelectric cooler (TEC). The SERS substrate is chemically modified with a thiol coating that prevents oxidation of the roughened silver surface and attracts the analyte of interest to the SERS surface. Using this sensor, detection of chlorinated solvents, aromatic compounds, and methyl t-butyl ether (MTBE) is demonstrated.