银胶溶液pH值对结晶紫的表面增强拉曼光谱增强效果的影响

通过NaBH4还原AgNO3制得银溶胶, 分析了结晶紫溶液表面增强拉曼光谱随银胶溶液pH值减小而逐渐减弱的机理。其原因是当加入酸改变银胶溶液pH值时, 在静电力作用下H+聚集在粗糙且存在偶电层(Ag+─负吸附质)的银胶表面, 使胶体中存在的表面等离子体共振吸附态的光吸收源随着H+浓度的增加逐渐减弱。并且H+与结晶紫的竞争作用又使结晶紫与银颗粒之间的吸附数量减少, 最终使结晶紫SERS强度随着pH值减小而逐渐减弱。我们测得银胶溶液的紫外──可见吸收光谱吸收峰强度随着pH值减小而逐渐减弱, 证明了分析的正确性。     

银胶体系中皮考酸的原位变温表面增强拉曼散射研究

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。     

草原毛虫核型多角体病毒包涵体在Ag胶中的表面增强拉曼光谱研究

本文获得了草原毛虫核型多角体病毒包涵体外膜蛋白在Ag胶中的表面增强拉曼光谱(SERS)。包涵体通过膜蛋白的COO~-和NH_2基团吸附在Ag表面上,其增强作用具有短程特性。低波数(～230cm~(-1))峰的出现表明包涵体和Ag胶粒子产生了化学吸附。包涵体在不同pH下的SERS谱很不同,说明此时它在Ag表面上的吸附状态有变化。     

胞嘧啶在沉积激光烧蚀Ag纳米颗粒电极上的SERS分析

用Nd:YAG激光器在二次去离子水中烧蚀银片,制备出了尺度分布均匀、并且具有很好的稳定性的"化学纯净"的Ag胶体系,并在电化学体系中将这种银胶沉积在粗糙的银电极表面,研究了胞嘧啶分子吸附在沉积Ag纳米颗粒电极表面随电极电位改变的表面增强拉曼光谱(SERS)。分析表明:(1)沉积银纳米颗粒的电极将金属电极与金属溶胶体系各自的优势很好的结合起来,形成了一种高效的SERS活性基底。(2)胞嘧啶在沉积银颗粒的电极表面以N3位竖直吸附,并且随着电位的负移,大多数SERS峰的位置发生了红移,表明胞嘧啶在电极表面吸附作用减弱。     

基于银胶纳米颗粒的痕量三硝基甲苯的表面增强拉曼光谱的实验研究

近年来对作为典型的硝基苯环类炸药的三硝基甲苯(TNT)的痕量检测受到越来越多的关注。将银胶纳米颗粒作为表面增强拉曼散射(SERS)基底,研究了10-6 mol.L-1的TNT的表面增强拉曼光谱的优化实验条件,重点研究了氯化钠溶液(NaCl)的含量以及碱性水解对TNT的表面增强拉曼光谱的影响。实验发现SERS样品中如果没有加入NaCl溶液,将观察不到TNT的SERS谱。加入的NaCl的含量必须在某一个范围之内才能观察到TNT的SERS谱,而且在这个范围之内,随着NaCl含量的增加,TNT的1 392cm-1处的拉曼峰出现先增大后减小的现象。对NaCl在TNT的SERS中的作用给予了理论解释。研究还发现TNT分子经过碱性水解后,与银纳米颗粒之间的吸附作用增强,其SERS谱的强度明显优于未经碱性水解的SERS结果。     

苯甲酸的羟基取代物在银纳米颗粒表面的吸附行为的研究

分别以覆银滤纸和银胶溶液中的银纳米颗粒为基底,对苯甲酸的三种羟基取代物(n-HBA,n=P,M,O)进行了表面增强拉曼散射(SERS),发现PHBA分子在覆银滤纸上的SERS光谱和银胶中的SERS光谱明显不同,而MHBA分子和OHBA分子在两种基底上的SERS光谱却很相近。分析表明这些变化都来源于分子在银纳米颗粒表面吸附行为的变化,基底的表面特性和分子的表面构型对分子在基底表面的吸附行为会产生很大的影响。     

菜粉蝶颗粒体病毒包涵体在银胶中的表面增强拉曼光谱研究

本文讨论了菜粉蝶(preris rtpae)颗粒体病毒(简称 PrGV )包涵体在银胶中的表面增强拉曼光谱。PrGV 包涵体的 SERS 谱与其 RS 谱之间存在一定对应关系。PrGV 包涵体蛋白分子通过羧基和氨基基团吸附于银粒子表面,并构成阴离子形式(NU_2RCOO~-)存在于溶液中。PrGV 在银胶中的表面增强的增强机制属于短程作用。PrGV 包涵体与银胶表面的吸附主要是化学吸附。     

胆红素络合物的表面增强拉曼光谱研究

本文通过对近红外激发傅里叶变换拉曼光谱(NIR-FT-Raman)与表面增强拉曼散射(Surface Enhanced Raman Scattering,SERS)技术的联用,测得胆红素及其络合物Na2BR,CaBR与CuBR在银溶胶中的SERS光谱.结果表明,这一类与胆结石密切相关的生物分子络合物具有不同的配位方式,且在银胶表面采取不同的吸附取向,并从配位化学角度初步解释了黑色结石的黑色成因.     

氯离子对固定银纳米颗粒SERS活性的影响

通过在硅片上修饰聚乙烯吡咯烷酮(PVP)对银纳米粒子进行组装,得到均一的表面增强拉曼光谱(SERS)基底。借助于此基底,在水溶液环境中,以异烟酸(INA)和罗丹明6g(R6g)作为探测分子,研究了氯离子(Cl-)对SERS增强的影响。结果表明,对于不同的探针分子,Cl-对银颗粒SERS活性的影响存在选择性。对于INA分子,在溶液中没有Cl-的情况下,分子通过羧基以锐角吸附在银颗粒表面,具有良好的SERS谱。在加入Cl-后,由于竞争吸附,INA分子脱附,SERS信号消失。R6g分子在银颗粒表面没有特异吸附,Cl-的加入并没有影响其与银颗粒的作用状态,在加入Cl-后SERS光谱没有发生显著变化。     

噻虫啉的表面增强拉曼光谱密度泛函理论研究

依据DFT理论的B3LYP方法下,在6-31G(d,p)(C,H,N,S,Cl)/Lanl2dz(Ag)基组,计算得到噻虫啉及其银配合物的稳定结构和表面增强拉曼光谱(SERS)。并进一步探究SERS与Ag4银簇吸附的位置,分子分别以单端(吡啶氮/氰基)和双端(吡啶氮和氰基)与Ag4银簇吸附。通过比较,TPD在双端吸附银簇下比单端(吡啶氮/氰基)吸附下的SERS(频率)更符合实验值。     

Multifunctional human serum albumin in the surface‐enhanced Raman spectroscopy of porphyrin: demetalation promoter,molecular spacer and stabilizer

Human serum albumin (HSA), a model protein, was introduced to the surface‐enhanced Raman spectroscopy (SERS) of cationic porphyrin 5,10,15,20‐tetrakis(1‐methyl‐4‐pyridyl)‐21H,23H‐porphine (H₂TMPyP4). HSA was found to have a great influence not only on Ag nanoparticle aggregation state but also on the interaction between Ag nanoparticle and H₂TMPyP4 molecules. In the (H₂TMPyP4‐Ag colloid)/HSA system, addition of H₂TMPyP4 to Ag colloid led to a quick Ag colloid aggregation, and subsequent HSA addition could stabilize this system. The SERS spectrum was dominated by a combination of Ag(II)TMPyP4 and free base H₂TMPyP4. More interestingly, a photoinduced demetalation of Ag(II)TMPyP4 to free base H₂TMPyP4 was observed in the (H₂TMPyP4‐Ag colloid)/HSA system. This demetalation process was partially reversible when the laser was turned off or the laser power was reduced. In this case, HSA acts as both a stabilizer and a demetalation promoter. In the (HSA‐H₂TMPyP4)/Ag colloid system, when H₂TMPyP4 was premixed with HSA prior to the Ag colloid addition, no obvious Ag colloid aggregation appeared, and the SERS spectrum was just characteristic of free base H₂TMPyP4. In this case, HSA is proposed to function as both a stabilizer and a molecular spacer. Copyright © 2010 John Wiley & Sons, Ltd.     

Distinguishable behavior of multiple and individual rhodamine‐6G molecules on spherical Ag nanoparticles examined via time dependence of the SERS spectra

We report a surface‐enhanced Raman spectroscopy (SERS) investigation to probe the adsorption and dynamic behavior of rhodamine 6 G (Rh6G) molecules on spherical Ag nanoparticles which were produced via laser ablation in liquid. Assembly of the colloidal Ag nanoparticles on a cover glass was used to work as SERS substrates on which high‐quality SERS spectra of Rh6G were obtained with interesting time dependence when using low and ultralow concentrations, respectively. The variation of SERS spectra over time was identified with the adsorption behavior of multiple and individual molecules on the Ag nanoparticles. Analysis indicates that the adsorbed Rh6G molecules can desorb away from the initial locations on the substrate under continuous laser excitation; simultaneously, some individual molecules can move and become trapped in the gap between the aggregated Ag nanoparticles. These investigations help to clarify the origins of forming ‘hot‐spots’ which host probe molecules and hence improve the understanding of mechanisms for single‐molecule SERS spectroscopy. Copyright © 2012 John Wiley & Sons, Ltd.     

四苯基卟啉及其金属配合物在溴化银胶体上的表面增强喇曼光谱研究

研究了四苯基卟啉（H2TPP）及其金属配合物（AgTPP和MgTPP）在AgBr胶体上的表面增强喇曼光谱（SERS）。SERS光谱表明,吸附在ArBr胶体粒子表面的MgTPP和H2TPP分子分别发生银离子交换和银配位反应生成AgTPP,这种表面反应可能与激光照射有关。AgTPP分子在胶体粒表面的吸附导致卟啉大环的非平面化,使v8振动（M－N键伸缩振动）向高波数方向移动近10cm^-1。632.8nm激发下的表面喇曼谱以化学增强为主,而488.0nm激发下表面喇曼谱除化学增强效应外,还存在共振增强效应。     

Surface-enhanced Raman scattering (SERS) spectra of Methyl Orange in Ag colloids prepared by electrolysis method

Polyvinyl alcohol (PVA)-protected Ag colloids were prepared by an electrolysis method. The surface-enhanced Raman scattering (SERS) spectra of Methyl Orange (MO), one of the Azo-dye molecules, in Ag colloids were successfully recorded with good concordance comparing to the theoretical results calculated by the Gaussian’98 program. The MO was adsorbed on the surface of Ag nanoparticles by trans-form which plays an important role for the SERS effect. However, the SERS spectra of MO in Ag colloids prepared by chemical reduction method did not appear which may be because of the competition of the borate or citrate ions with the MO. In order to test the applicability of these colloids, the SERS spectra of Sudan red (III) (SR), another of Azo-dye molecules, were measured and the result was good.     

Surface enhanced Raman scattering (SERS) of chemisorbed species on various kinds of metals and semiconductors

SERS spectra of pyridine adsorbed on various kinds of vacuum evaporated (10^?5 Torr) metals (Ag, Au, Ni, Pd, Pt, Ti and Co) and on single crystals of semiconductors (NiO and TiO₂) were obtained at room temperature. The peak frequencies as shifted from those of free pyridine are assigned to the bands of N-bonded pyridine (chemisorbed pyridine). The λ₀ dependence varied remarkably from metal to metal. The peak frequency and the λ₀ dependence for the pyridine adsorbed on NiO or TiO₂ are in good agreement with those on Ni or Ti, respectively, showing the chemical bonding between the N atom and the Ni or Ti atom. The effects of background and of polarization on the SERS spectra were examined in detail, thus revealing the orientation of the adsorbed molecules. Carbon monoxide chemisorbed on Ag was measured by infrared specular reflection as well as by SERS. The results indicate that chemisorbed species on the same substrate do not always give SERS. The SERS spectra obtained are well interpreted as being due to the mechanism of resonance Raman scattering via charge transfer excitation of the adsorbent-adsorbate interaction.     

在银、金和铂基底上银纳米粒子诱导的单层有机分子的表面增强拉曼散射(英文)

Noble metallic nanostructures exhibit a phenomenon known as surface-enhanced Raman scattering （SERS） in which the scattering cross sections are dramatically enhanced for molecules adsorbed thereon. Thanks to the enormously large enhancement factor on the order of 106～1015, one can readily acquire thevibrational spectra from adsorbates on roughened surfaces of Ag, Au, and Cu. However, SERS has not developed to be as powerful a surface technique as many people had hoped initially because of two specific obstacles.     

KCl和HCl对结晶紫分子NIR-SERS作用机制的比较研究

本文研究了ＫＣｌ与ＨＣｌ对结晶紫分子近红外表面增强拉曼光谱（ＮＩＲ－ＳＥＲＳ）的影响。表明在以离子作为其ＳＥＲＳ信号的额外增强剂的过程中，更多地注意到对分子结构的选择性对于获得理想的ＳＥＲＳ结构非常必要。     

运用表面增强拉曼散射(SERS)和密度泛函数理论(DFT)模拟计算研究对硝基苯胺在金纳米颗粒表面吸附行为

在沉积金纳米颗粒的干燥滤纸上进行对硝基苯胺的表面增强拉曼散射(SERS)光谱研究,并与对硝基苯胺在金胶水溶液中的表面增强拉曼散射(SERS)光谱相比,分子拉曼光谱发生了很大变化。同时利用DFT理论计算对硝基苯胺在金胶颗粒上的吸附行为的拉曼光谱。DFT理论模拟计算和FI-Raman实验分析都表明这种变化源于对硝基苯胺的不同吸附方式。SERS和DFT结合研究分子的吸附是一种有效的技术。     

咖啡酸分子表面增强拉曼光谱的理论与实验研究

咖啡酸（CA）是一种具有很高的医学价值的药物成分，在抗菌抗病毒方面应用广泛，尤其是咖啡酸及其衍生物在抗肿瘤方面有着巨大作用，现在对咖啡酸的相关研究越来越多，但大部分都是关于咖啡酸医学性质的研究，所以对咖啡酸分子的微观结构研究是非常有必要的。目前关于CA在Ag表面上的表面增强拉曼散射（SERS）光谱的理论与实验结合的研究尚未见报道，而对其振动光谱及表面增强机理的研究可以为咖啡酸的各种药学机理的研究提供一种科学的物理解释，所以有必要将密度泛函理论（DFT）方法与表面增强拉曼散射技术相结合，对咖啡酸在Ag纳米颗粒上的吸附性质及表面增强机理进行全面的研究，这对推进它们在医药学等领域的相关研究有着重要的参考价值。采用SERS与DFT技术对CA分子在Ag纳米颗粒表面上的表面增强拉曼光谱进行了研究。在实验方面，利用热还原反应原理，使用柠檬酸三钠和硝酸银在加热搅拌情况下制备Ag纳米颗粒，并使用激光共聚焦显微拉曼光谱仪测量了CA分子的常规拉曼散射（NRS）光谱及其表面增强拉曼散射（SERS）光谱。在理论计算方面，采用DFT的B3LYP方法，以6-31+G**和LANL2DZ分别作为C，H，O和Ag的计算基组来优化咖啡酸的分子构型，羟基与Ag₄的吸附构型，羧基与Ag₄的吸附构型，羟基与羧基共同与Ag₄吸附的构型，并以此为基础分析计算了CA分子的NRS光谱以及三种可能吸附模型的SERS光谱，并结合实验结果进行比较。同时对CA分子的振动模式进行了详细指认。根据实验数据和理论结果分析，在452 cm-1处的谱峰归属为环面外弯曲振动和O-H面外弯曲振动的耦合，这说明CA分子上的酚羟基是与Ag纳米颗粒表面作用的，不过相互作用较弱，推测CA分子平面可能与Ag基底表面不垂直；出现在1 338 cm-1处的谱峰归属于COO-伸缩振动，则可以说明CA分子上的羧基可能与Ag纳米颗粒垂直吸附。结果表明，CA分子是以羧基和酚羟基为吸附位吸附在Ag纳米颗粒表面上的。同时对CA分子的振动模式进行了详细指认。该工作对推进咖啡酸在生物医药等领域进一步的应用将起到重要作用。