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卤化物对水扬酸分子表面增强喇曼信号的影响 总被引:2,自引:0,他引:2
研究了几种卤化物对水扬酸分子表面增强喇曼信号的影响,给出了表面增强喇曼谱(SERS)强度随卤离子浓度的变化及对时间的变化过程.并且对影响表面增强喇曼信号的机理进行了一定的分析. 相似文献
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<正> 一引言表面增强喇曼现象(SERS)是指在银、铜、金等粗糙电极上吸附的分子的喇曼散射截面比正常的喇曼散射截面大百万倍的现象.表面增强喇曼峰强的一个最大特点是谱峰的相对强度随电压的变化而变化.同时这谱峰的相对强度也和液态或水溶液中的不同.至目前为止,文献上有关 SERS 的报导,还大都只局限在谱峰位置的变化这个角度上,即研究谱峰的消失,出现以及移动等.我们知道谱峰的移动是由于化学键强的变 相似文献
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本文根据0.005mol/L 4,4′-联吡啶/0.010mol/L氯化钾体系的循环伏安曲线、SERS光谱及随外加电位的变化情况,研究4,4′-联吡啶吸附在银电极上的SERS光谱及随外加电位的变化,探讨它们在银电极表面的吸附方式。一、引言自从发现吡啶吸附在银电极表面上产生表面增强喇曼散射(SERS)效应后,这个领域的研究日益深入。1987年,张 相似文献
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采用热蒸镀的方法直接在多孔氧化铝(porous anodic alumina,PAA)模板上蒸镀几微米的银膜,然后在HCl溶液中溶解掉模板,得到表面具有纳米尺度规则结构的银膜作为表面增强拉曼散射(surface-en-hanced Raman spectra,SERS)基底,并在该基底上测量了吡啶溶液(0.01 mol.L-1)的增强拉曼光谱,发现平均增强因子大于105。与直接在载玻片上蒸镀的银膜相比,具有纳米尺度规则结构银膜的增强效果提高了30倍。改变激发光功率测量吡啶的拉曼光谱,和普通拉曼散射一样,增强拉曼光谱的峰值强度随激发光强度线性变化,并在该基底上测量了三聚氰胺的拉曼光谱,发现在1 mW的激发功率下对于三聚氰胺的检出限为2.5 mg.L-1。 相似文献
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文中从实验和计算两方面报道了在514.5 nm激发光下P-Thiocresol吸附在银胶表面系统的表面增强拉曼散射(SERS).文中分析了它的增强机制,发现增强主要来自于电磁场增强.如果考虑距离为2nm的两个银纳米粒子的耦舍效应,两粒子之间的SERS的电磁场增强为7.16 × 107.静态化学增强亦起到部分增强作用,它的增强倍数为6.所以,总的SERS增强,包括静态化学增强和电磁场增强,是Gtotal=Gsc ×GEM=4.4×108.我们也理论地研究了此系统的表面增强共振拉曼散射(SERRS).当激发光与P-Thiocresol-Ag3系统的激发态共振时,电荷转移机制(化学增强)也将起到重要作用,最强的增强可迭106.我们使用电荷密度将激发光下p-Thlocresol和Ag团簇问的电荷转移结果可视化,这是电荷转移的直接理论证据.对于SERRS增强,包括电荷转移和电磁场增强机制,能达到1013. 相似文献
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Lixin Xia Yi Jia Guangye Liu Zhilin Yang Xiaowei Chen Huili Zhang Mengtao Sun 《Journal of Raman spectroscopy : JRS》2010,41(4):398-405
Metal pellets of silver and copper for surface‐enhanced Raman scattering (SERS) spectroscopy were prepared by compression with different pressures. It was found that the SERS activity of the pellet could be controlled by pressure. Enhanced Raman scattering properties of the metal pellets in the presence of adsorbed 4‐mercaptobenzoic acid (4‐MBA) with excitation at 632.8 or 514 nm could be obtained by choosing proper pressure of pellatization. The SERS peak intensity of the band at ∼1584 cm−1 of 4‐MBA adsorbed on the metal pellets varies as a function of applied pressure, and which is about 1.2–32 times greater than when it is adsorbed on silver and copper particles. The calculated results of three‐dimensional finite‐difference time‐domain method (3D‐FDTD) are in good agreement with the experimental data. Moreover, no spurious peaks appear in the SERS spectra of the samples because no other chemicals are involved in the simple preparation process of the metal pellets, which will facilitate its use as an SERS‐active substrate for analytical purposes. In summary, SERS‐active metal pellets can be produced simply and cost effectively by the method reported here, and this method is expected to be utilized in the development of SERS‐based analytical devices. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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Kwan Kim Seung Hun Lee Kyung Lock Kim Kuan Soo Shin 《Journal of Raman spectroscopy : JRS》2013,44(4):518-524
Silver thiolate is a layered compound with a Raman spectrum that is known to change with time, becoming the same as the surface‐enhanced Raman scattering (SERS) spectrum of the parent thiol molecule adsorbed on Ag nanoparticles. On this basis, the Raman scattering characteristics of silver 4‐aminobenzenethiolate (Ag‐4ABT) compounds were investigated to determine whether certain peaks that are identifiable in the SERS spectrum of 4‐aminobenzenethiol (4‐ABT) but absent in its normal Raman spectrum were also apparent in the Ag salt spectrum. For comparative purposes, the Raman scattering characteristics of silver 4‐dimethylaminobenzenethiolate (Ag‐4MABT) were also examined. Raman spectra acquired while spinning the sample were typified by only a1‐type vibrational bands of Ag‐4ABT and Ag‐4MABT, whereas in the static condition, several non‐a1‐type bands were identified. The spectral patterns acquired in the static condition were similar to the intrinsic SERS spectra of 4‐ABT or 4‐dimethylaminobenzenethiol (4‐MABT) adsorbed on pure Ag nanoparticles. Notably, the CH3 group vibrational bands were observable for Ag‐4MABT irrespective of the sample rotation. In addition, no decrease in intensity during irradiation with a visible laser was observed for any of the bands, suggesting that no chemical conversion actually took place in either 4‐ABT or 4‐MABT. The preponderance of evidence led to the conclusion that the non‐a1‐type bands observable in the SERS spectra must be associated with the chemical enhancement mechanism acting on the Ag nanoparticles. The chemical enhancement effect was more profound at 514.5 nm than at 632.8 nm, and was more favorable for 4‐ABT than 4‐MABT at both wavelengths. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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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。 相似文献
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用1064nm激发的近红外傅里叶变换表面增强拉曼散射技术研究腺嘌呤系列胡凤霞方炎(首都师范大学综合技术研究所,北京100037)FourierTransformSurface-EnhancedRamanSpectroscopyofSeriesofAd... 相似文献
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电化学体系中吸附在金电极表面吡啶的紫外拉曼光谱研究 总被引:2,自引:1,他引:1
观察到波长为325nm的紫外光激发下吸附在金电极表面的吡啶的表面增强拉曼光谱(SERS)。结合其SERS谱随电位的变化关系,分析了其中的增强机制并表明随电位的负移吡啶的吸附方式发生改变。 相似文献
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A. C. Sant'Ana T. C. R. Rocha P. S. Santos D. Zanchet M. L. A. Temperini 《Journal of Raman spectroscopy : JRS》2009,40(2):183-190
Surface‐enhanced Raman scattering (SERS) spectra of 2‐amino‐5‐nitropyridine (ANP) adsorbed on colloidal silver triangular nanoplates were obtained using samples with different mean sizes and surface plasmon frequencies. The relative SERS enhancement factor for each sample was determined by the analysis of the normalized SERS excitation profiles of ANP vibrational modes for nanoplates in suspension, without aggregation. The SERS profiles are blue‐shifted in relation to the localized surface plasmon peak. The detailed characterization of both morphology and concentration of the samples in addition to a rigorous normalization of the SERS spectra allowed a quantitative correlation between the SERS profiles and the mean size of the nanoplates. This correlation indicated the existence of an optimum size of the nanoplates for maximum Raman enhancement. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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We report the observation of large surface‐enhanced Raman scattering (SERS) (106) for 4‐tert‐butylpyridine molecules adsorbed on a silver electrode surface in an electrochemical cell with electrode potential set at − 0.5 V. A decrease in electrode potential to − 0.3 V was accompanied by a decrease in relative intensities of the vibrational modes. However, there were no changes in vibrational wavenumbers. Comparison of both normal solution Raman and SERS spectra shows very large enhancement of the intensities of a1, a2, and b2 modes at laser excitation of 488 nm. Enhancement of the non‐totally symmetric modes indicates the presence of charge transfer as a contributor to the enhancement. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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G. V. Pavan Kumar 《Journal of Raman spectroscopy : JRS》2009,40(12):2069-2073
Surface‐enhanced Raman scattering from carbon nanotube bundles adsorbed with plasmon‐tunable Ag‐core Au‐shell nanoparticles (Ag@Au nps) was carried out for the first time. By utilizing nanoparticles whose plasmon resonance peak (541, 642 nm) closely matches the commonly used Raman excitation sources (532, 632.81 nm), we can observe a large enhancement in the Raman signatures of carbon nanotubes. We obtain greater enhancement in the Raman signal for the above case when compared to nanotubes adsorbed with conventional Ag, Au or other ‘off resonant’ Ag@Au nps. The power‐dependent SERS experiment on single‐walled nanotubes (SWNTs) with resonant Ag@Au nps reveals a linear behavior between the G‐band intensity and the photon flux density, which is in agreement with the vibrational pumping model of SERS. The observed enhancement by resonance matching is pronounced for carbon nanotubes and may lead to insights into understanding nanotube–nanoparticle interaction. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献