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。     

拉曼散射技术在光合作用研究中的应用

本文阐述拉曼光谱技术在光合系统各个研究领域中的应用。包括以下几个方面:(1)估测二氢叶酚型电子载体的分子结构;(2)测定与蛋白相结合的类胡萝卜素分子的构象;(3)强光破坏前后PdOECC的SERS光谱的研究。研究结果表明拉曼光谱是研究光合作用体系结构的有力工具。     

基于SERS研究光动力治疗中的癌细胞损伤

光动力治疗(PDT)是一种涉及光及光敏剂(光敏药物)与分子氧结合用于诱导细胞损伤或死亡的光化学治疗方法~([1]),因对正常细胞器官损伤轻微而被广泛应用。其过程是用特定波长光照射癌变部位,使选择性聚集在癌变部位的光敏药物活化,从而引发光化学反应破坏癌细胞。表面增强拉曼光谱(SERS)作为分子振动光谱技术,具有灵敏度高、检测速度快、无损及免标记等优点。基于此,本研究设计构筑一种基于靶向细胞器的等离激元探针,用于选择性获得特定细胞器的SERS光谱,通过SERS对光动力治疗过程中的细胞损伤进行分析,为光动力治疗机制提供评价依据。     

溶液酸碱性对金纳米粒子在端基功能化单分子膜表面组装影响的SERS光谱研究

在4,4’-二硫联吡啶在Au表面形成自组装单分子层膜的基础上,采用表面增强拉曼散射光谱(SERS)研究了在不同pH值条件下金纳米粒子在4,4’-二硫联吡啶自组装单分子膜/Au体系表面的组装。研究结果表明,由于处于单分子膜表面的吡啶环中氮原子的质子化程度随溶液环境中pH值的变化而变化,使得金纳米粒子与单分子膜表面间的结合作用程度不同,由此会引起金纳米粒子在单分子膜表面的覆盖度存在差异,并最终导致所观测到的4-巯基吡啶自组装单分子膜的SERS光谱强度存在明显的差异。而且,令人感兴趣的是,所观测到的SERS谱峰强度随金纳米粒子组装时pH值的变化呈现出明显的规律性。结合分子结构特征的分析,初步阐明了SERS谱峰强度随pH值这一组装条件的改变而发生规律性变化的内在原因。     

在酸、碱条件下甘氨酸酐在正电性纳米银上的SERS研究

测定了甘氨酸酐的Raman谱以及甘氨酸酐在酸、碱环境条件下在正电性纳米银上的表面增强拉曼散射光谱(SERS),用B3LYP/6-31g(d)计算了甘氨酸酐的Raman光谱,借助理论计算的结果对实验得出的Raman光谱及酸性环境条件下的SERS进行了指认,得知在此条件下分子物理吸附在纳米银上;碱性环境条件下的甘氨酸酐的SERS与酸性环境条件下的甘氨酸酐的SERS谱及甘氨酸酐的Raman谱相比有了较大的变化,经过分析, 可以认为甘氨酸酐可能在银表面发生水解反应成了为甘氨酸二肽。     

甲氧苄氨嘧啶的表面增强拉曼光谱研究

利用表面增强拉曼光谱 (SERS)和高效薄层色谱 (TLC)分离技术的结合 ,获得了研究甲氧苄氨嘧啶光谱的新方法。SERS结果表明 ,在TLC原位 6μg就可获得该分子的主要振动谱带 ,在银微粒作用下 ,嘧啶环伸缩获得明显增强 ,可以较可靠地反映出分子结构信息。     

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。     

维生素K3的表面增强拉曼光谱研究

首次报道了维生素K3 (VK3 )分子的常规拉曼光谱 (NRS)及该分子在活性衬底银镜上的表面增强拉曼散射 (SERS) ,并对它的拉曼特征谱带进行了初步的指认和归属。通过对比VK3 的常规拉曼光谱和SERS谱 ,发现VK3 分子吸附在银表面后拉曼散射强度被大大增强了。另外 ,VK3 的羰基与银粒子发生电荷转移后形成负离子自由基 ,碳氧双键打开。受VK3 分子吸附在银镜表面的影响 ,萘环结构发生了很大的扰动 ,导致一些拉曼特征峰产生位移 ,环变形振动对应的拉曼散射强度得到了增强。这些研究结果为SERS技术今后对VK3进行药物检测以及痕量分析方面的应用提供了依据。     

钩藤中异钩藤碱在TLC原位的FT-SERS研究

本文报道了将薄层色谱（TLC）与傅里叶变换表面增强拉曼散射（FT－SERS）联用，获得了中草药钩藤中的异钩藤碱光谱研究的新方法。研究表明，在薄层原位，2.5μg钩藤总碱可将异钩藤碱等8种生物碱完全分离。应用薄层原位的薄层色谱傅里叶变换表面增强拉曼散射（TLC－FT－SERS）技术，获得异钩藤碱分子的特征振动谱带，进而阐述了样品分子在银胶表面的吸附模式，异钩藤碱以分子中氧化吲哚基团上N原子的孤子电子对和吲哚环π电子共同吸附于银晶体微粒表面,1.615cm^-1与芳环骨架振动和氧化吲哚N－H变形振动相关的峰获得最大增强。说明TLC－FT－SERS对中草药化学成分进行高灵敏度示踪指纹检测的可靠性和优越性。     

小檗碱在TLC原位的FT-SERS研究

应用表面增强技术将薄层色谱与近红外傅里叶变换拉曼光谱联用，获得了中成药三黄片中主要有效成分小檗碱在薄层原位的傅里叶变换表面增强拉曼光谱（FT－SERS）。研究表明，在薄层原位约2.5μm样品的FT－SERS与纯固体样品的FT－Raman光谱的主要特征峰波数基本一致，相对强度有一定变化，出现特别增强的拉曼峰是波数为727nm的芳香环上CH键面内变形振动峰。小檗碱分子以异喹啉环共轭体系的π电子与表面增强活性物质银晶体微粒相互作用，呈平面吸附样式。获得了中成药三黄片中主要有效成分小檗碱分离与高灵敏度指纹检测的可靠的新方法。     

Visible light response of silver 4‐aminobenzenethiolate and silver 4‐dimethylaminobenzenethiolate probed by Raman scattering spectroscopy

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.     

Vibrational spectroscopic studies and computational study of methyl(2‐methyl‐4,6–dinitrophenylsulfanyl)ethanoate

FT‐IR and FT‐Raman spectra of methyl(2‐methyl‐4,6–dinitrophenylsulfanyl)ethanoate (MDIE) were recorded and analyzed. Surface‐enhanced Raman scattering (SERS) spectra were recorded in silver colloid and silver electrode. The vibrational wavenumbers were computed using HF/6‐31G* and B3LYP/6‐31G* basis. The data obtained from vibrational wavenumber calculations are used to assign vibrational bands obtained in infrared and Raman spectroscopies as well as in SERS of the studied molecule. The first hyperpolarizability and infrared intensities are reported. The geometrical parameters of the title compound are in agreement with the reported similar derivatives. The presence of new bands at 1045 and 948 cm⁻¹ in the SERS spectrum in silver electrode is related to the change in orientation of the molecule with respect to the metal surface. In silver colloid SERS spectrum, the methyl group attached to the methoxy carbonyl group is close to the metal surface, whereas on silver electrode the methyl group attached to the phenyl ring is close to the metal surface. Copyright © 2009 John Wiley & Sons, Ltd.     

温度变化对金属Ag膜反射镜偏振特性的影响研究

空间遥感应用中的光学有效载荷对系统偏振控制提出了越来越高的要求,作为常用的宽光谱反射镜,金属银(Ag)膜反射镜的偏振特性随着环境温度的改变而变化。本文设计并制备了低偏振灵敏度的Ag膜反射镜,研究了反射镜在45°和60°入射角下,从室温25℃升温到150℃时的偏振特性变化和反射光谱变化情况。随着温度的升高,Ag膜的折射率在350~1 200 nm波长范围内有所增加;Ag膜反射镜的反射光中s和p光的相位差Δ在350~600 nm波长范围内减小,在600~650 nm波长范围内基本稳定,在650~1 200 nm波长范围内增大。温度上升到125℃时,Ag膜和反射镜表面形貌发生改变,增加了表面散射和吸收,导致350~900 nm波段反射率降低,在波长350 nm附近的降低约25%。     

Surface‐enhanced Raman scattering on colloid gels originated from low molecular weight gelator

Surface‐enhanced Raman scattering (SERS) on silver and gold colloid gels formed by a low molecular weight organic gelator, bis‐(S‐phenylalanine) oxalyl amide, was obtained. Strong Raman signals dominate in the SERS spectra of hydrogels containing silver nanoparticles prepared by citrate and borohydride reduction methods, whereas broad bands of low intensity are detected in the spectra of gold colloid gels. Resemblance between Raman spectrum of the crystalline substance and the SERS spectra of the silver nanoparticle–hydrogel composites implies the electromagnetic nature of the signal enhancement. A change in Raman intensity of the benzene and amide II bands caused by an increase in temperature and concentration indicates that the gelling molecules are strongly attached through the benzene moieties to the metal nanoparticles while participating in gel formation by intermolecular hydrogen bonding between the adjacent oxalyl amide groups. Transmission electron microscopy reveals a dense gel structure in the close vicinity of the enhancing metal particles for both silver colloid gels. Copyright © 2008 John Wiley & Sons, Ltd.     

半胱氨酸作为耦联剂制备的纳米银膜上的SERS研究

在直流10V电压下电解聚乙烯醇和硝酸银的混合液3h制备纳米银胶,将经过半胱氨酸修饰后的载玻片浸入银胶24h制得纳米银膜。用紫外可见分光光度计对银胶进行了观测,由于其吸收峰半高宽较窄可知银胶中纳米银颗粒粒径分布较为均匀。同时,使用扫描电镜对银膜进行了表征。通过对半胱氨酸分子SERS信号的分析得出了纳米银粒子在玻璃表面上可能的组装方式。以结晶紫(Crystal Violet)和孔雀石绿(Malachite Green)作为探测分子,采用便携式拉曼光谱仪测得两种分子不同浓度下的SERS谱。发现该方法所制得的纳米银膜有很好的表面增强效果。最后分析了半胱氨酸分子SERS信号对探针分子光谱的影响。     

Surface Enhanced Raman Scattering on Self-assembled Nano Silver Film Prepared by Electrolysis Method

用一种廉价的电解方法制备了纳米银膜,并详细研究了在这种银膜上的表面增强拉曼散射效果．结晶紫为本实验的检测性分子．通过实验发现,这种银膜用便携式拉曼光谱仪测试并计算出的表面增强拉曼散射的增强因子为603,并对结晶紫的最小检出限为0.1 nmol/L     

Fluorescence and surface-enhanced vibrational spectroscopies of lawsone and plumbagin

The natural dyes lawsone and plumbagin (1,4-naphthoquinones) were studied by using fluorescence, Raman, infrared (IR), surface-enhanced Raman scattering (SERS), and surface-enhanced IR absorption. From the absorption spectrum, it was possible to infer that the enol-lawsone tautomer concentration decreases in silver colloidal solution. Plumbagin dimers, both in water and in silver colloidal solution, were identified from the fluorescence band profile and surface-SERS spectrum. The SERS spectrum of lawsone was obtained by using silver colloidal solution after 12-hour settle; the keto and enol lawsone silver colloid interaction occurs. The assignment of Raman and IR bands of both dyes was calculated with density functional theory calculations. Only a monomeric structure of lawsone interacting with a silver cluster model was predicted. The monomer adopts a nearly coplanar orientation onto the silver surface; the shortest distance is 3.2 Å, suggesting an electrostatic interaction.     

The detection by SERS of resonantly excited desorption of pyridine from silver island films by IR laser absorption

We have shown that when a very thin film of pyridine about two or three monolayers thick on a silver island film is exposed to a pulsed CO₂ laser line whose frequency corresponds to that of a pyridine vibrational mode the physisorbed molecules within the pyridine film can be desorbed even at liquid He temperatures. It is interesting that this observation was first made using surface enhanced Raman scattering. Experimental results are presented from which it is concluded that the phenomenon can be described as resonantly excited desorption. The absorbed IR energy seems to be localized within the pyridine film and the silver film and thermallized to some degree causing some of the physisorbed molecules to desorb. Analysis of the SERS spectra before and after the resonantly excited desorption has enabled us to separate out the SERS spectra due to the physisorbed pyridine and the chemisorbed pyridine.