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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 总被引:1,自引:0,他引:1
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AgBr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分子在胶体粒子表面的吸附导致卟啉大环的非平面化,使vs振动(M-N键伸缩振动)向高波数方向移动近10 cm-1.632.8 nm激发下的表面喇曼谱以化学增强为主,而488.0 nm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. 相似文献
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铜表面缓饰的喇曼光谱电化学研究 总被引:1,自引:0,他引:1
近年来,随着国民经济的发展,金属缓蚀研究越来越受到人们的重视,在金属缓蚀机理研究中最常用的手段就是电化学方法和现场光谱技术,特别是表面增强喇曼散射光谱技术(SERS);由于它极大的增强效应,可以用其研究金属表面微量物质的吸附行为.它不需要其它现场光谱技术所必需的高真空、高温等技术,即可得到吸附在金属表面物质的结构信息.本文对两种缓蚀剂[‘],2一氨基苯并咪吐和6一硝基苯并咪娃在铜表面的吸附行为进行了喇曼光谱电化学研究,通过改变铜电极电位对两种缓蚀剂的各主要喇曼振动谱带进行了观察,对它们在银表面的吸附… 相似文献
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利用种子介导的软模板生长方法制备了金纳米线(Au NWs)阵列, 通过调节生长温度控制Au NWs阵列的形貌, 最后在经硼氢化钠(NaBH4)清洗过的Au NWs阵列上化学沉积银纳米颗粒(Ag NPs), 制得银/金纳米线(Ag/Au NWs)阵列作为表面增强拉曼散射(SERS)基底. 选用罗丹明6G(R6G)作为拉曼探针分子测定了Ag/Au NWs阵列的SERS性能. 结果表明, Ag/Au NWs阵列作为SERS基底具有高灵敏度、 优异的信号均匀性和良好的稳定性. 使用Ag/Au NWs阵列对孔雀石绿(MG)检测的检出限可低至1×10-8 mol/L, 线性范围为 1×10-8~1×10-4 mol/L. NaBH4可以在不影响SERS性能的情况下去除Ag/Au NWs阵列上吸附的分子, 使得 SERS基底可以重复使用. 使用Ag/Au NWs阵列对湖水中的MG进行检测, 得到了可靠的回收率, 证明Ag/Au NWs 阵列在检测环境水体中的孔雀石绿上具有应用潜力. 相似文献
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研究了2-氨基苯并咪唑(BIMNH_2)、LiCl、NaOEt对Ag/EtOH溶胶吸收光谱和表面增强Raman散射(SERS)光谱的影响。结果表明,少量的吸附分子BIMNH_2、LiCl、NaOEt均能改变溶胶聚集状态,从而影响其吸收光谱和SERS效应。此外,Cl~-还可与Ag、BIMNH_2形成表面络合物而增强SERS效应。对Ag溶胶体系SERS光谱的溶剂效应也作了初步研究。 相似文献
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采用自组装技术在硅基底上进行金银纳米粒子的混合组装, 通过控制组装溶液中金银溶胶的体积比而控制基底上金银纳米粒子的密度. SEM结果显示金银呈亚单层均匀分布, 以吡啶为探针分子, 在不同波长的激发光下研究了纯金、银以及混合组装时的SERS效应. 利用金银在不同激发线下增强效应的不同以及探针分子吸附在金银纳米粒子表面主要谱峰相对强度差别的特点, 通过一系列校正以及差谱方法研究了金银共存时SERS效应的变化, 并分离出混合体系中金的增强行为, 结果表明在金银同时组装时吡啶的SERS谱峰特征主要表现为银纳米粒子的行为, 分离出的金SERS光谱特征接近银的行为, 说明金银纳米粒子之间产生了一定的耦合作用. 相似文献
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四苯基卟吩化合物的表面增强喇曼散射 总被引:3,自引:0,他引:3
自首次发现表面增强喇曼散射(SERS)并计算了其增强倍数后,现已发展成为一个十分活跃的研究领域,并先后采取金属电极、真空镀膜、银溶胶等方法达到增强的目的.本文采用化学还原镀银法研究了四苯基卟吩(简称TPP)系列化合物在银表面的SERS。TPP类化合物尽管边缘取代物有很大差别,但其中心核相似.某些TPP类化合物的共振喇曼谱和红外光谱已有过报导。本文讨论了TPP金属络合物与自由碱基TPP化合物在SERS中存在差别的原因,提出了TPP化合物在银表面的吸附态,探讨了SERS的增强机理。 相似文献
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以制备的MOF@TiN-Ag/银溶胶复合基底为表面增强拉曼光谱(SERS)活性基底,对茶碱进行SERS检测,探讨了基于该复合基底的表面增强拉曼技术在药物检测方面的应用。首先,利用电化学阳极氧化结合氨气还原氮化法制备了氮化钛纳米管阵列,随后通过电化学沉积法制备TiN-Ag复合基底,并在其表面原位生长金属有机框架(MOF)包覆层得到MOF@TiN-Ag复合基底,将茶碱与银溶胶混合后滴加在该复合基底上进行表面增强拉曼光谱检测。结果表明,MOF@TiN-Ag/银溶胶复合基底中存在面心立方晶型TiN、金属单质Ag和MOF钴基3种物相;扫描电镜结果显示,TiN纳米管排列整齐,Ag纳米结构呈树枝状均匀分散在其表面;作为隔绝层的MOF粒子形状规整,覆盖在TiN-Ag表面;银溶胶纳米粒子呈圆球状分布在MOF@TiN-Ag复合基底表面。由于银纳米粒子与TiN-Ag复合基底可发生协同增强作用,加之MOF的富集特性,使得该复合基底具有优异的SERS性能,其对茶碱溶液的SERS检出限为1×10-5 mol/L,检测性能良好。所制备的MOF@TiNAg/银溶胶复合基底拓宽了SERS在药物检测... 相似文献
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Abdelsalam ME Mahajan S Bartlett PN Baumberg JJ Russell AE 《Journal of the American Chemical Society》2007,129(23):7399-7406
Palladium and platinum are important catalytic metals, and it would be highly advantageous to be able to use surface enhanced Raman spectroscopy (SERS) to study reactive species and intermediates on their surfaces. In this paper we describe the use of templated electrodeposition through colloidal templates to produce thin (<1 microm) films of palladium and platinum containing close packed hexagonal arrays of uniform sphere segment voids. We show that, even though these films are not rough, when the appropriate film thickness and sphere diameter are employed these surfaces give stable, reproducible surface enhancements for Raman scattering from molecules adsorbed at the metal surface. We report SERS spectra for benzenethiol adsorbed on the structured palladium and platinum surfaces of different thicknesses and void diameters and show that, for 633 nm radiation, enhancements of 1800 and 550 can be obtained for palladium and platinum, respectively. 相似文献
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Li X Xu W Zhang J Jia H Yang B Zhao B Li B Ozaki Y 《Langmuir : the ACS journal of surfaces and colloids》2004,20(4):1298-1304
In this paper, we propose two new approaches for preparing active substrates for surface-enhanced Raman scattering (SERS). In the first approach (method 1), one transfers AgI nanoparticles capped by negatively charged mercaptoacetic acid from a AgI colloid solution onto a quartz slide and then deoxidizes AgI to Ag nanoparticles on the substrate. The second approach (method 2) deoxidizes AgI to Ag nanoparticles in a colloid solution and then transfers the Ag nanoparticles capped by negatively charged mercaptoacetic acid onto a quartz slide. By transfer of the AgI/Ag nanoparticles from the colloid solutions to the solid substrates, the problem of instability of the colloid solutions can largely be overcome. The films thus prepared by both approaches retain the merits of metal colloid solutions while they discharge their shortcomings. Accordingly, the obtained Ag particle films are very suitable as SERS active substrates. SERS active substrates with different coverages can be formed in a layer-by-layer electrostatic assembly by exposing positively charged surfaces to the colloid solutions containing oppositely charged AgI/Ag nanoparticles. The SERS active substrates fabricated by the two novel methods have been characterized by means of atomic force microscopy (AFM) and ultraviolet-visible (UV-vis) spectroscopy. The results of AFM and UV-vis spectroscopy show that the Ag nanoparticles grow with the increase in the number of coverage and that most of them remain isolated even at high coverages. Consequently, the surface optical properties are dominated by the absorption due to the isolated Ag nanoparticles. The relationship between SERS intensity and surface morphology of the new active substrates has been investigated for Rhodamine 6G (R6G) adsorbed on them. It has been found that the SERS enhancement depends on the size and aggregation of the Ag particles on the substrates. Especially, we can obtain a stronger SERS signal from the substrate prepared by method 1, implying that for the metal nanoparticles capped with stabilizer molecules such as mercaptoacetic acid, the in situ deoxidization in the film is of great use in preparing SERS active substrates. Furthermore, we have found that the addition of Cl- into the AgI colloid solution changes the surface morphology of the SERS active substrates and favors stronger SERS enhancement. 相似文献
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Surface-enhanced Raman scattering (SERS) spectroscopy and surface-enhanced infrared absorption (SEIRA) spectroscopy are analytical tools suitable for the detection of small amounts of various analytes adsorbed on metal surfaces. During recent years, these two spectroscopic methods have become increasingly important in the investigation of adsorption of biomolecules and pharmaceuticals on nanostructured metal surfaces. In this work, the adsorption of B-group vitamins pyridoxine, nicotinic acid, folic acid and riboflavin at electrochemically prepared gold and silver substrates was investigated using Fourier transform SERS spectroscopy at an excitation wavelength of 1,064 nm. Gold and silver substrates were prepared by cathodic reduction on massive platinum targets. In the case of gold substrates, oxidation–reduction cycles were applied to increase the enhancement factor of the gold surface. The SERS spectra of riboflavin, nicotinic acid, folic acid and pyridoxine adsorbed on silver substrates differ significantly from SERS spectra of these B-group vitamins adsorbed on gold substrates. The analysis of near-infrared-excited SERS spectra reveals that each of B-group vitamin investigated interacts with the gold surface via a different mechanism of adsorption to that with the silver surface. In the case of riboflavin adsorbed on silver substrate, the interpretation of surface-enhanced infrared absorption (SEIRA) spectra was also helpful in investigation of the adsorption mechanism. 相似文献
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D. Alberts V. Vega R. Pereiro N. Bordel V. M. Prida A. Bengtson A. Sanz-Medel 《Analytical and bioanalytical chemistry》2010,396(8):2833-2840
The development of highly ordered and self-assembled magnetic nanostructures such as arrays of Fe or Ni nanowires and their
alloys is arousing increasing interest due to the peculiar magnetic properties of such materials at the nanoscale. These nanostructures
can be fabricated using nanoporous anodic alumina membranes or self-assembled nanotubular titanium dioxide as templates. The
chemical characterization of the nanostructured layers is of great importance to assist the optimization of the filling procedure
or to determine their manufacturing quality. Radiofrequency glow discharge (RF-GD) coupled to optical emission spectrometry
(OES) is a powerful tool for the direct analysis of either conducting or insulating materials and to carry out depth profile
analysis of thin layers by multi-matrix calibration procedures. Thus, the capability of RF-GD-OES is investigated here for
the in-depth quantitative analysis of self-aligned titania nanotubes and self-ordered nanoporous alumina filled with arrays
of metallic and magnetic nanowires obtained using the template-assisted filling method. The samples analysed in this work
consisted of arrays of Ni nanowires with different lengths (from 1.2 up to 5 μm) and multilayer nanowires of alternating layers
with different thicknesses (of 1–2 μm) of Ni and Au, or Au and FeNi alloy, deposited inside the alumina and titania membranes.
Results, compared with other techniques such as scanning electron microscopy and energy-dispersive X-ray spectroscopy, show
that the RF-GD-OES surface analysis technique proves to be adequate and promising for this challenging application. 相似文献
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Palladium is an important catalytic metal, and it is desirable to develop a surface-enhanced Raman scattering (SERS) technique to investigate the reagent and product species adsorbed on its surface. Unfortunately, Pt-group metals, e.g., Pt and Pd, have been commonly considered as non- or weak-SERS-active substrates. In this work, Ag and Pd thin films were deposited very efficiently and evenly onto the surface of glass substrates by using only corresponding metal nitrate salts (AgNO3 and Pd(NO3)2) with butylamine in ethanolic solutions. In this process, pure ethanol was used for Ag deposition, while an ethanol–water (8:2) mixture was used for Pd deposition. The as-prepared Ag and Pd films exhibited SERS activity over a large area. The surface-induced photoconversion capabilities of these Ag and Pd films were then tested on 4-nitrobenzenethiol by means of SERS. It was found that at least under visible laser irradiation, the surface-catalyzed photoreaction occurs more readily on a Ag film than on a Pd film for the conversion of 4-nitrobenzenethiol to 4-aminobenzenethiol, even though Pd is known to be an important transition metal with high catalytic activity. 相似文献
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Tunable Surface‐Enhanced Raman Scattering from High‐Density Gold Semishell Arrays with Controllable Dimensions 下载免费PDF全文
Xianzhong Lang Dr. Jiaqi Li Xiaoguang Luo Yan Zhang Yin Yin Prof. Teng Qiu 《Chemphyschem》2014,15(2):337-343
A convenient reproducible technique is reported for the fabrication of large‐area gold semishell arrays by mechanically pressing porous anodic alumina (PAA) stamps into gold/polymer bilayer structures that serve as robust and cost‐efficient surface‐enhanced Raman‐scattering (SERS) substrates. The surface structure can be tuned further to optimize the enhancement factor according to optional PAA fabrication parameters and imprinting pressures. Finite‐difference time‐domain calculations indicate that the structure may possess excellent SERS characteristics due to the high density and abundance of hot spots. 相似文献
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One dimensional (1D) nanostructures have many possible applications in electronic, optical, and sensing devices associated with their nanosized lateral dimensions. In this regard, a general and bottom-up strategy to synthesize 1D nanoparticle arrays and conductive nanowires with a facile structural/compositional control is highly desired. We herein report a protein-sheathed single walled carbon nanotube (SWNT) that satisfies the criteria for an ideal template to assemble micron-long gold nanoparticle (AuNP) linear arrays with high structural rigidity. The resulting AuNP array has minimized inter-particle gaps, which is especially useful to template the overgrowth of Ag, Pd, and Pd/Ag metals into continuous nanowires (Au@M, M=Ag, Pd, Ag/ Pd). Our method successfully overcomes the incompatibility between carbon and metal materials, and the resulting superstructured metal nanowires have a tunable diameter below 100 nm and a shape closely replicating a SWNT. The Ag nanowires are composed of coalesced Au@Ag coreshell nanoparticles, while the Pd and Pd/Ag nanowires are made of very fine Pd nanocrystallites around the AuNP cores. These unique structural features are pivotal to various applications including surface enhanced Raman scattering (SERS), electrocatalysis, and gas sensors. 相似文献