锌的表面增强喇曼散射效应

本文从莫育俊等人提出的天线共振子模型理论出发,计算了金属锌的SERS增强特性。天线共振子模型预言,在可见光区,锌的增强因子最大为10,而在红外则会达到很大的增强(10⁵以上).同时,我们通过实验分析了金属锌的SERS增强特性,得到了在可见光区锌的增强因子约为230.在考虑化学增强的情况下,理论计算结果同实验基本一致。     

钴钯铂的表面增强喇曼散射效应研究

利用天线共振子模型对钴钯铂的表面增强喇曼散射特性进行了计算和分析, 计算结果表明钴钯铂的增强分别为1、≤4、2～4, 实验测量的最大增强分别为≤5、105和140, 在考虑化学增强的情况下, 理论同实验是一致的; 在经氧化还原过程处理的钴钯铂片上做了核酸碱基胞嘧啶的SERS谱, 结果反映三种衬底上的SERS谱强弱不同, 以铂最大, 钴最小, 而且, 三种衬底对于胞嘧啶各振动模式的增强基本一致.     

金纳米颗粒阵列基底的化学置换制备及其表面增强拉曼散射特性研究

表面增强拉曼(SERS)作为一种分析手段,具有高灵敏度、高选择性、高重复性、非破坏性等优点,在过去的几十年中,被广泛应用在成分检测、环境科学、生物医药及传感器等领域。其中以金、银等贵金属纳米颗粒薄膜在表面增强拉曼(SERS)活性基底方面得到了更为广泛的应用。SERS技术一个关键的因素是如何制设计并备具有大面积、高增强能力及高重复性、可循环使用的SERS基底。通常,贵金属纳米颗粒规则阵列结构的单元颗粒电磁增强特性及其颗粒间的电磁耦合增强特性的综合作用可大力提升SERS基底的探测性能。然而,利用传统微纳米加工方法如光刻、电子束光刻等方法制备得到的贵金属纳米阵列结构的表面粗糙度不够理想。结合光刻与化学置换方法制备金纳米颗粒四方点阵列孔洞结构,并研究其作为SERS基底的电磁增强特性。具体研究利用光刻法在硅衬底上制备了规则排列的四方点阵列孔洞结构,用磁控溅射在其表面镀上金属铁膜;接着在衬底上旋涂浓度为1.893 8 mol·L-1的氯金酸液膜,在孔洞内铁和氯金酸发生置换反应,进而孔洞生成金纳米颗粒,最终得到金纳米颗粒四方点阵SERS活性基底。采用罗丹明6G(R6G)分子作为探测分子测试不同金纳米颗粒阵列结构基底的SERS谱。实验结果表明,随着化学置换反应时间的延长,金纳米颗粒排列更加紧凑有序,SERS谱增强性能更好。     

AAO模板法制备CdS纳米微粒的SERS光谱研究

在自制的孔径约15nm多孔氧化铝模板上沉积银纳米粒子,然后用电化学方法在此衬底上沉积CdS纳米微粒。研究了CdS纳米阵列在457.5nm波长激光激发下的表面增强拉曼散射(SERS)性质。实验结果显示CdS的SERS信号有三个振动模式,分别对应1LO、2LO和3LO纵光学声子模,它们的强度随着作为SERS衬底的银纳米粒子高度的增加而增强,当银纳米粒子的长/径比(长度与直径的比值)达到4时,这种增强趋近饱和。最后对CdS纳米微粒光学声子模的增强机理进行了分析和讨论。     

浸镀法制备SERS活性金衬底研究

研究了一种新的表面增强拉曼性金衬底的制备方法.该方法使用AuCl3水溶液，在金属铝表面浸镀金镀层从而制得金衬底.通过扫描电子显微镜观察到铝基底表面的金镀层呈岛状分布，且其平均粒径约为80 nm.分别检测到吡啶和聚乙烯吡咯烷酮（PVP）两种探针分子在金衬底上的SERS谱.通过计算可知,该SERS活性金衬底的增强因子大于105.这种衬底在空气中放置一段时间后仍能保持较好的增强效果，说明它在空气中比较稳定.     

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。     

银片上茜素的表面增强共振喇曼散射效应及模式标识

本文对吸附在经连续的氧化 还原循环(ORC)过程处理的银片衬底上的茜素的表面增强共振喇曼散射(SERRS)特性进行了研究,并对茜素SERRS谱中的振动模式做了标识.结果表明,吸附在经氧化.还原循环(ORC)处理的银片衬底上的茜素分子,其表面增强喇曼散射的强度,主要是由于最靠近银片的一层分子的增强,而第一层以外的分子贡献很小.也就是说,表面增强喇曼散射具有单层饱和效应.茜素在经ORC处理的银片上和在银镜上所显示的SERRS特征基本一致,其中有些振动模式存在小的频移,这与银片、银镜各自的表面特性有关.     

树枝状银微米材料的制备及其表面增强拉曼光谱研究

为使表面增量拉曼散射(SERS)衬底的制备方法简单快速且提高的基底增强效果,采用置换反应的制备方法,用锌片和硝酸银反应制备出微米银结构SERS活性基底,其具有稳定性好,易保存,制备方法简单,过程快速等特点。用扫描电子显微镜观察得银微米材料表面形貌呈均匀对称的树枝状结构。实验中控制置换反应的时间分别为40,50,60 s时,得到的树枝状银微米材料的长度分别为3,5,10 μm左右,分支分别为700 nm,2 μm,3 μm,发现随着置换反应的时间的增长,微米银树枝及分枝的长度越长,且树枝分枝上逐渐长出纳米级“树叶”结构, 使得微米级银树枝表面具有纳米结构。并且将微米银材料置于硅片上作为SERS衬底,并以罗丹明6G为探针分子,用激发波长为1 064 nm的傅里叶变换拉曼光谱仪检测,研究其在表面增强拉曼光谱中的应用,结果表明树枝状银微米材料有很好的SERS特性,其中置换反应时间为40 s时制备的微米银树枝的增强效果最佳,其增强因子可达到103左右,并且采用用表面活性剂PVP处理硅片的方法后,保持其他条件不变,微米银衬底的SERS增强效果得到进一步加强,增强因子达到104左右。此外,将树枝状银微米材料用水可封存数月,且实验结果的重复性较好。     

有机半导体-纳米银复合基底的制备及其在表面增强拉曼光谱中的应用

工业染料的大规模生产和广泛应用给地球生态带来了相当大的影响，对水环境污染非常严重，而传统色谱和光谱工具难以检测到微弱的光谱和化学信息，因此开发便携快速的检测技术至关重要。表面增强拉曼光谱(SERS)是一种与纳米技术相结合的新型分析技术，可以实现单分子量级化学物质的检测，但潜力容易受到SERS基底的增强能力、稳定性等普适性问题限制。研究提出了一种简单而通用的策略，制备了一种基于疏水性有机半导体双(二氰基亚甲基)-封端-二噻吩并[2,3-d; 2’,3’-d]苯并[2,1-b; 3,4-b’]-二噻吩(4CN-DTmBDT)薄膜为衬底的新型SERS复合基底。首先通过旋涂法制备有机半导体衬底，该π共轭有机半导体具有分子结构可控、生物相容性、光电特性可微调、成膜形态参数可控等优势，衬底表面具有疏水性使纳米银粒子(AgNPs)在其表面形成紧密咖啡环，制备有机半导体-纳米银SERS复合基底，探究基底拉曼信号的增强效果。同时提出了一种该有机半导体与纳米银粒子的协同增强机制，并对增强能力与增强机理进行了相关研究。结果表明，紧密咖啡环的形成减小了银纳米颗粒之间的空间，检测时通过浓缩分析物，从而增强了热点...     

卤酸根离子的近红外表面增强Raman散射

用近红外激光激发研究了卤酸根离子在银胶中的表面增强Raman散射（SERS）．实验结果表明，ClO^－₃和BrO^－₃离子在银胶颗粒表面只有单个的SERS带，分别位于226和158cm^-1处，而IO^－₃离子却在334和750cm^－1处出现两个SERS峰．这些结果表明ClO^－₃和BrO     

Silver-coated Si nanograss as highly sensitive surface-enhanced Raman spectroscopy substrates

We created novel surface-enhanced Raman spectroscopy (SERS) substrates by metalization (Ag) of Si nanograss prepared by a Bosch process which involves deep reactive ion etching of single crystalline silicon. No template or lithography was needed for making the Si nanograss, thus providing a simple and inexpensive method to achieve highly sensitive large-area SERS substrates. The dependence of the SERS effect on the thickness of the metal deposition and on the surface morphology and topology of the substrate prior to metal deposition was studied in order to optimize the SERS signals. We observed that the Ag-coated Si nanograss can achieve uniform SERS enhancement over large area (∼1 cm ×1 cm) with an average EF (enhancement factor) of 4.2×10⁸ for 4-mercaptophenol probe molecules. Electronic Supplementary Material  The online version of this article () contains supplementary material, which is available to authorized users.     

Silver macro‐texture substrates fabricated by plasma selective etching for surface‐enhanced Raman scattering

We have demonstrated a novel method to generate the nanostructured substrate that shows a large enhancement with a spatially uniform enhancement factor of approximately 10⁶ in surface enhanced Raman scattering (SERS). The substrates are fabricated using plasma selective etching. First, the Al₂O₃–TiC template which contains mixed Al₂O₃ and TiC grains with the diameters of ~400 nm is selected as a base plate. The Al₂O₃ and TiC grains have different physical properties, such as hardness, which corresponds to different etching rate in a plasma gas. Then, the Al₂O₃–TiC substrate is selectively etched to generate a random macro‐texture (MT) with different depths using the plasma of mixed gas of Ar and C₂H₄. Third, the MT substrate is deposited with a silver film (Ag). We further demonstrate that by varying the thickness of Ag layer, the EF is different which is confirmed by the plasmonic localized electric fields calculations using finite difference time domain. Finally, we combine this novel Ag MT substrate with ultrathin dielectric film, and the prepared substrates are coated with a 10 Å ta‐C film. The 10 Å ta‐C film can protect the oxygen‐free Ag in air and prevent Ag ionizing in aqueous solutions. More importantly, the ultrathin ta‐C can release the strongest plasmonic electric field to the outside of ta‐C layer and get a higher electric field than the uncoated Ag substrate. We expect that this method has more potential applications in analytic assays using SERS technology. Copyright © 2012 John Wiley & Sons, Ltd.     

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.     

Controlling SERS intensity by tuning the size and height of a silver nanoparticle array

It is demonstrated that the surface-enhanced Raman scattering (SERS) intensity of R6G molecules adsorbed on a Ag nanoparticle array can be controlled by tuning the size and height of the nanoparticles. A firm Ag nanoparticle array was fabricated on glass substrate by using nanosphere lithography (NSL) combined with reactive ion etching (RIE). Different sizes of Ag nanoparticles were fabricated with seed polystyrene nanospheres ranging from 430 nm to 820 nm in diameter. By depositing different thicknesses of Ag film and lifting off nanospheres from the surface of the substrate, the height of the Ag nanoparticles can be tuned. It is observed that the SERS enhancement factor will increase when the size of the Ag nanoparticles decreases and the deposition thickness of the Ag film increases. An enhancement factor as high as 2×10⁶ can be achieved when the size of the polystyrene nanospheres is 430 nm in diameter and the height of the Ag nanoparticles is 96 nm. By using a confocal Raman mapping technique, we also demonstrate that the intensity of Raman scattering is enhanced due to the local surface plasmon resonance (LSPR) occurring in the Ag nanoparticle array.     

Surface‐enhanced Raman scattering‐based approach for DNA detection at low concentrations via polyvinyl alcohol‐protected silver grasslike patterns

A simple method is demonstrated to detect DNA at low concentrations on the basis of surface‐enhanced Raman scattering (SERS) via polyvinyl alcohol‐protected silver grasslike patterns (PVA‐Ag GPs) grown on the surface of the common Al substrate. By the SERS measurements of sodium citrate and thymine, the PVA‐Ag GPs are shown to be an excellent SERS substrate with good activity, stability and reproducibility. With the use of the tested molecule of thymine, the enhancement factor of the PVA‐Ag GPs is up to ~1.4 × 10⁸. The PVA‐Ag GPs are also shown to be an excellent SERS substrate with good biocompatibility for DNA detection, and the detection limit is down to ~10⁻⁵ mg/g. Meanwhile, the assignations of the Raman bands and the adsorption behaviors of the DNA molecules are also analyzed. In this work, the geometry optimization and the wavenumber analysis of adenine–Ag and guanine–Ag complexes for the ground states are performed using density functional theory, B3LYP functional and the LanL2DZ basis set. The transition energies and the oscillator strengths of adenine–Ag and guanine–Ag for the lowest six singlet excited states were calculated by using the time‐dependent density functional theory method with the same functional and basis set. The results show that the charge transfer in the adenine–Ag and guanine–Ag complexes should be the chemical factor for the SERS of the DNA molecules. Lastly, this method may be employed in large‐scale preparation of substrates that have been widely applied in the Raman analysis of DNA because the fabrication process is simple and inexpensive. Copyright © 2011 John Wiley & Sons, Ltd.     

A facile method for the synthesis of large‐size Ag nanoparticles as efficient SERS substrates

Silver nanoparticles (Ag NPs) enjoy a reputation as an ultrasensitive substrate for surface‐enhanced Raman spectroscopy (SERS). However, large‐scale synthesis of Ag NPs in a controlled manner is a challenging task for a long period of time. Here, we reported a simple seed‐mediated method to synthesize Ag NPs with controllable sizes from 50 to 300 nm, which were characterized by scanning electron microscopy (SEM) and UV–Vis spectroscopy. SERS spectra of Rhodamine 6G (R6G) from the as‐prepared Ag NPs substrates indicate that the enhancement capability of Ag NPs varies with different excitation wavelengths. The Ag NPs with average sizes of ~150, ~175, and ~225 nm show the highest SERS activities for 532, 633, and 785‐nm excitation, respectively. Significantly, 150‐nm Ag NPs exhibit an enhancement factor exceeding 10⁸ for pyridine (Py) molecules in electrochemical SERS (EC‐SERS) measurements. Furthermore, finite‐difference time‐domain (FDTD) calculation is employed to explain the size‐dependent SERS activity. Finally, the potential of the as‐prepared SERS substrates is demonstrated with the detection of malachite green. Copyright © 2016 John Wiley & Sons, Ltd.     

Experimental parameters for the SERS of nitrate ion for label‐free semi‐quantitative detection of proteins and mechanism for proteins to form SERS hot sites: a SERS study

We have explored the effects of the experimental parameters on the surface‐enhanced Raman scattering (SERS) intensities of NO₃⁻ and proteins observed by a heat‐induced SERS method developed by our group. The results have shown that a strong SERS signal can be obtained at pH 4.0, using an Ag colloid prepared with the reduction time of 15 min (the average size of Ag nanoparticle is 56.5 nm) dilution prepared Ag colloid by a factor of 2 by use of a 5 mM citrate buffer, using 6 mM NaNO₃ and drying the sample at 100 °C, respectively. Based on the results, two possible mechanisms for proteins to form SERS hot sites during the sample preparations are proposed. A semi‐quantitative SERS detection of ribonuclease B has been investigated. Also, NaNO₂, Mg (NO₃)₂, MgSO₄ and Na₂SO₄ have been found to be suitable for the heat‐induced SERS method. Importantly, samples prepared by the heat‐induced SERS method are so stable that these samples can be used as a standard and transferred to different laboratories for direct comparison. Namely, it can overcome uncontrollable aggregation of Ag colloids in a solution sample. All these advantages and the simplicity of experimental setup have demonstrated that the heat‐induced SERS method using NaNO₃ as an electrolyte is very promising for label‐free routine and quantitative detection of proteins. Copyright © 2011 John Wiley & Sons, Ltd.     

Self-assembled Ag nanoparticles for surface enhanced Raman scattering

Uniform and reproducible substrates for surface enhanced Raman scattering (SERS) are fabricated by self-assembly of Ag nanoparticles (NPs) on 3-aminopropyltrimethoxysilane (APTES) modified glass. Experimental results indicate that the Ag NPs with a narrow size distribution were assembled as a sub-monolayer which exhibits an excellent SERSactivity. The SERS enhancement factor is estimated to be 7.5 × 10⁶ and the detection limit for crystal violet (CV) solution is about ～10^?11 M. The uniformity and reproducibility of the SERS signals are tested by point-to-point and batch-to-batch measurements. It is confirmed that the self-assembled Ag NPs substrates has a high SERS reproducibility and a low standard deviation with respect to the Ag NPs on non-functionalized glass substrates. The self-assembled Ag NPs substrates can be widely used for the application of chemical and biochemical sensing.     

Diamine-linked array of metal (Au,Ag) nanoparticles on glass substrates for reliable surface-enhanced Raman scattering (SERS) measurements

Metal (Au, Ag) nanoparticles (M NPs) (ca. 30–40 nm) prepared by citrate reduction method were arrayed on amine-terminated glass substrates using diamine linkers with different chain lengths. 1,4-diaminobutane (C-4 diamine) produced the uniform and densely-packed array of M NPs on glass substrates at appropriate concentration ranges, whereas diamine linkers with longer chain lengths (C-8 and C-12 diamines) produced more heterogeneous and aggregated array of M NPs. When compared to Ag NPs, Au NPs demonstrated more controllable and higher packing density due to their mono-dispersed size and higher affinity to diamine linkers. Uniformly arrayed M NPs (Au, Ag) on glass substrates exhibited high enhancement factors in SERS measurements of o-chlorothiophenol probes. Au NPs arrayed substrates exhibited an approximate power-law linearity of Raman intensity with probe concentrations (from 10⁻⁷ M to 10⁻⁴ M), demonstrating more reliable SERS substrates than Ag arrayed substrates with higher SERS activity.     

Clean and reproducible SERS substrates for high sensitive detection by solid phase synthesis and fabrication of Ag‐coated Fe3O4 microspheres

The solid‐phase synthesis of Ag‐coated Fe₃O₄ microsphere was elaborated under argon atmosphere. This straightforward process utilized neither reducing agents nor electric current and involved the dry mixing of a precursor of CH₃COOAg with Fe₃O₄ microspheres followed by heating in an inert atmosphere. Ag nanoparticles with diameters of 30–50 nm were well‐decorated on the surfaces of Fe₃O₄ microspheres. The as‐synthesized Ag‐coated Fe₃O₄ microspheres were assembled into a surface‐enhanced Raman scattering (SERS) substrate holding clean and reproducible properties under an externally exerted magnetic force. Using these nanoprobes, analyte molecules can be easily captured, magnetically concentrated, and analyzed by SERS. This clean SERS substrate was used to detect 4‐aminothiophenol, even at a concentration as low as1.0 × 10^–12 M. In particular, the Ag‐coated Fe₃O₄ microspheres, acting as reproducible SERS substrates, were applied to detect methyl‐parathion and 4‐mercaptopyridine. Strong SERS signals were obtained with the analytes at a concentration of 1.0 × 10^–6 M. The unique, clean, and reproducible properties indicate a new route in eliminating the single‐use problem of traditional SERS substrates and show promising applications for detecting other organic pollutants. Similarly, this work may provide a new model system to a series of metal–Fe₃O₄ decorating reactions for a reproducible utilization. Copyright © 2012 John Wiley & Sons, Ltd.