维生素C在不同pH值下的拉曼光谱和表面增强拉曼光谱

报道了维生素C(VC)的FT-拉曼光谱和在银胶基底上的表面增强拉曼光谱(SERS),并对它的拉曼特征谱带进行了初步的指认和归属.结合pH值的变化探讨了吸附作用的特点和规律.实验结果表明,1748、1651、1372、1256、562、446cm-1、和149cm-1处都能看到表面增强,VC的内酯环是以倾斜的方向吸附于银胶表面,并且VC分子是通过O-H键吸附在银胶表面上的,并在吸附过程中与银发生了电荷转移而形成负离子自由基,碳氧双键打开.     

基于密度泛函的伪麻黄碱拉曼光谱性质研究

研究伪麻黄碱的拉曼光谱和吸附在纳米银基底上的表面增强拉曼光谱(SERS),利用密度泛函理论B3LYP/6-311G++(d, p)方法对伪麻黄碱分子进行了计算，得到了分子构型信息和理论拉曼光谱，用Gaussview软件对分子振动模式进行了全面的归属，在伪麻黄碱的表面增强拉曼光谱中，采用了自组装方法获得了团簇银纳米表面增强基底，实现了很好的增强效应.实验结果表明：伪麻黄碱的拉曼光谱计算结果和实验结果基本一致，理论计算为伪麻黄碱分子振动峰位的归属提供了重要的依据，伪麻黄碱分子与银纳米表面化学吸附，苯环垂直于纳米基底表面，研究结果为伪麻黄碱的拉曼光谱检验分析提供了理论依据，也为苯丙胺类毒品的光谱分析研究提供了参考.     

六氢吡啶的表面增强拉曼散射研究

表面增强拉曼光谱在化学、生物及表面科学等领域都有广泛应用, 因此六氢吡啶的表面增强拉曼光谱的研究具有重要意义。实验用法国JOBIN YVON公司的光谱仪测定了六氢吡啶的正常拉曼光谱及其在银溶胶、银膜表面的表面增强拉曼光谱(SERS), 确保了实验结果的可靠性。利用表面增强拉曼散射技术研究了六氢吡啶的拉曼谱, 对它的拉曼峰进行了指认, 并得出了在银表面的吸附方式。同时分析了六氢吡啶在银溶胶及银膜表面拉曼散射光强增强程度不同的原因。     

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。     

浓度对活性艳红染料在粗糙银表面上吸附的影响

利用化学还原的方法制备了银溶胶，通过测定活性艳红浓度从10^-4－10^-8mol/L在粗糙的银表面上的表面增强拉曼光谱的变化，地活性艳红浓度与表面增强拉曼强度的关系及活性艳红在银溶胶表面的吸附取向。结果表明，活性艳红在10^-5mol/L时，表面增强拉曼信号最强，说明在此浓度时，活性艳红在银溶胶上的吸附量达到饱和；而大于此浓度后，过量的活性艳红分子在银溶胶上发生叠加，拉曼信号减弱，这种现象符合“稀溶液效应”。     

氯化亚锡吸附与配位作用下L-肌肽的表面增强拉曼光谱

利用在电极表面强化学吸附的氯化亚锡与被测有机/生物分子之间的相互作用,不仅可以有效消除被测分子的碳化和氧化现象,还可以获得特别的增强信号,可应用于反应活性强的有机/生物分子的表面增强拉曼光谱分析。还报道了肌肽的电化学表面增强拉曼散射(SERS)光谱的研究结果,重点考察了加入氯化亚锡前后和改变电极电势对肌肽吸附SERS光谱的影响。无氯化亚锡时,肌肽的SERS光谱存在严重的碳化信号的干扰;氯化亚锡存在下,调控电极电势可引起吸附的氯化亚锡与肌肽在电极表面发生配位作用,借助这种表面相互作用,可将肌肽固载于基底表面,从而获得L-肌肽的高质量表面增强拉曼光谱,完全消除碳化现象的干扰。     

腺嘌呤、嘌呤和四并苯的表面增强拉曼光谱随温度的可逆变化

用硝酸腐蚀法处理得到了具有表面增强拉曼光谱 (SERS)活性的银表面。在表面温度于 - 1 90℃～30℃变化时 (上升和下降 ) ,分别测定了吸附在银表面上的腺嘌呤、嘌呤和四并苯的表面增强拉曼光谱 ,观察到一系列有关拉曼峰频率和强度的可逆变化。结果表明 ,温度降低 ,吸附分子SERS中受电磁增强机制作用的振动的拉曼位移发生蓝移 ,同时峰强度也有变化 ;而受化学增强机制作用的振动的拉曼位移则不受温度的影响。温度的变化导致分子平面可弯曲分子在金属表面的取向发生变化 ,如腺嘌呤和嘌呤在高温下取直立态 ,而平面的对称分子 (如四并苯 )在表面上的取向则不受温度的影响。     

针尖增强拉曼光谱中物理与化学效应的实验研究

针尖增强拉曼光谱(Tip-Enhanced Raman Spectroscopy,TERS)的增强机制中物理和化学效应的影响是一个非常重要的研究课题。通过采用基于原子力显微镜平台的针尖增强拉曼光谱系统,深入研究了金纳米光栅表面苯硫酚的针尖增强拉曼效应。通过与相同样品在表面增强拉曼光谱系统中不同模式的增强因子对比,发现在TERS中物理效应和化学效应对其拉曼信号的增强均有贡献,同时TERS技术会带来更大的化学增强效应,尽管在针尖加载的过程中并未改变苯硫酚与金光栅基底之间的化学环境。这种现象可以归因于苯硫酚分子在垂直金属表面方向上的各向异性及其与针尖表面电荷和外加光电场之间相互作用的影响。本文的研究促进人们对TERS机理的理解,为进一步完善TERS增强理论奠定基础。     

基于“热点”效应的表面增强拉曼散射光谱研究

本文利用罗丹明6G在银胶体粒子聚集点上的表面增强拉曼光谱的强度变化,采用逐点扫描获得拉曼光谱的"Mapping"方法,获得了不同的银胶体粒子聚集点对吸附的R6G表面增强拉曼光谱强度的影响。分析了"热点"对拉曼散射的增强的作用,表明"热点"的增强强度和纳米粒子的聚集程度有关。     

亚乙基硫脲的表面增强拉曼极化率研究：电磁和电荷转移机制

测量了吸附在银电极表面的亚乙基硫脲分子在不同电位下的表面增强拉曼光谱，对光谱强度变化进行了分析.从拉曼光谱强度计算出分子的键极化率数值，分析极化率大小和变化情况，提出了分子在不同电位下表面增强效应的增强机制. 关键词： 亚乙基硫脲 表面增强拉曼极化率 电磁增强 电荷转移增强     

碳纳米管拉曼光谱研究新进展

本文介绍碳纳米管拉曼光谱研究的最新进展。重点介绍金属性和半导体性碳纳米管的共振拉曼效应、表面增强拉曼效应和偏振拉曼效应。同时也介绍了碳纳米管的温度效应、压力效应和杨氏模量的拉曼光谱研究     

Raman sum rule and the relation to the infrared sum rule in La2-xSrxCuO4

Electronic Raman scattering has no sum rule in no and weak correlation, but the existence of sum rule has been proposed in strong correlation. The present Raman scattering disclosed that the first moment of the Raman susceptibility is proportional to the generalized moment of the optical conductivity in the metallic phase. The present experiment disclosed that a large amount of electronic states are incoherent states. The incoherent states are the relevant states for the superconductivity, because the gap opens in the incoherent states as well as the coherent states.     

New features in the anti‐Stokes and Stokes Raman spectra of single‐walled carbon nanotubes that are highly separated into their semiconducting and metallic nanotube components

Surface‐enhanced Raman scattering studies were performed using nonresonant (514.5 nm) and resonant (676.4 nm) optical excitations on single‐walled carbon nanotubes thoroughly separated into semiconducting (pure 99%) and metallic (pure 98%) components. Regardless of the support (Au or Ag), the metallic nanotubes do not present an anomalous anti‐Stokes Raman emission. Regardless of whether an on‐resonant or off‐resonant optical excitation is used, only the semiconducting nanotubes produce an abnormal anti‐Stokes Raman emission that grows when increasing the excitation light intensity or temperature. The Raman studies under light polarized relative to the main nanotube axis demonstrate that only semiconducting nanotubes are sensitive toward changes in the polarization of the excitation light. Copyright © 2014 John Wiley & Sons, Ltd.     

High-energy phonon branches of an individual metallic carbon nanotube

We present excitation-energy dependent Raman measurements between 2.05 and 2.41 eV on the same individual carbon nanotube. We find a change in the Raman frequencies of both the D mode (63 cm(-1)/eV) and the high-energy modes. The observed frequencies of the modes at approximately 1600 cm(-1) as a function of laser-energy map the phonon dispersion relation of a metallic tube near the Gamma point of the Brillouin zone. Our results prove the entire first-order Raman spectrum in single-wall carbon nanotubes to originate from double-resonant scattering. Moreover, we confirm experimentally the phonon softening in metallic tubes by a Peierls-like mechanism.     

单壁碳纳米管-聚合物复合材料的拉曼光谱表征(英文)

本文在粗糙金属表面上制作了单壁碳纳米管—聚乙烯醇复合材料,并利用表面增强拉曼散射讨论了碳纳米管与聚乙烯醇之间的相互作用     

Three-dimensional optical trapping of partially silvered silica microparticles

We demonstrate three-dimensional trapping of micrometer-diameter silica particles, partially coated with silver, within conventional optical tweezers. Although metallic particles are usually repelled from the beam focus by the scattering force, we show that transparent spheres partially coated with silver can be trapped with efficiencies comparable with dielectric particles. The trapping characteristics of these particles are examined as a function of metallic coverage, and the application of these particles to surface-enhanced resonance Raman scattering is investigated.     

Effects of in-plane oxygens on the magnetic response in cuprates

A brief analysis of ARPES, Raman, and neutron data is used to show the importance of the oxygen degree of freedom for the metallic phase of cuprate high-T_c superconductors. It is based on published results and a number of new calculations, relevant to Raman and neutron scattering in the metallic underdoped and optimally doped regime. They are placed in the context of a recently developed theoretical understanding of the microscopic interplay between metallicity and local valence-bond fluctuations in the cuprates. It is argued that the oxygen degree of freedom is dominantly responsible for the metallicity in the normal state. The coexistence of metallic oxygen-dominated states with localized copper-dominated states is a key experimental constraint on the microscopic understanding of the normal-state pseudogap proposed here, especially of its strong k-dependence.     

Highly ordered periodic array of metallic nanodots fabricated through template‐assisted nanopatterning and its use for surface‐enhanced Raman scattering spectroscopy of flexible crystalline‐silicon nanomembranes

We report on the fabrication of highly uniform periodic arrays of metallic nanodots formed on glass substrates through a facile anodic aluminum oxide template‐assisted process and their use in selective surface‐enhanced Raman scattering spectroscopy to probe the structural properties of flexible crystalline‐silicon nanomembranes deposited on polymer substrates. A 14‐fold enhancement in Raman scattering was observed from the thin flexible silicon membranes deposited on polyethylene terephthalate substrates, which were used to probe the internal strains in the silicon nanomembrane as a function of the bending radius. Copyright © 2011 John Wiley & Sons, Ltd.     

Evidence of the Fano resonance in a temperature dependent Raman study of CaCu3Ti4O12 and SrCu3Ti4O12

Phononic excitations have been investigated using Raman scattering studies on CaCu(3)Ti(4)O(12) and SrCu(3)Ti(4)O(12) compounds as a function of temperature down to 10 K. Evidence of the Fano resonance effect is found in the A(g)(1) mode with an asymmetric phonon line shape that occurs because of composite electron-phonon scattering due to the onset of metallic fractions in the system. The evolution of the Fano line shape with temperature affirms the existence of nanoscale phase separation and the prominence of orbitally disrupted metallic regions above 100 K. Anomalies in the evolution of the line width of the A(g)(1) Raman mode with temperature are observed around 100 K where these compounds show an orbital order/disorder transition. These anomalies manifest mutual coupling of orbital degrees of freedom to lattice degrees of freedom.     

热分解羧酸银形成银膜技术的发展对表面增强拉曼光谱学的贡献(英文)

pacc:7830,7300Noblemetallicnanostructuresexhibitaphe nomenonknownassurface-enhancedRaman scattering(SERS)inwhichthescatteringcross sectionsaredramaticallyenhancedformolecules adsorbedthereon.TouseSERSinroutine,on-linestudiesforanalyticalpurposes,thesubstr…