用于电化学界面研究的共焦显微拉曼光谱技术(英文)

系统地介绍了将共焦显微拉曼光谱系统用于电化学界面研究的方法 ,包括铂电极的粗糙和电化学拉曼电解池的设计 .进行了铂上氢、氧和氯共吸附的拉曼光谱研究 .通过对甲醇氧化过程的现场跟踪 ,提出检测界面区溶液浓度变化和计算溶液 pH值的方法 .实验表明拉曼光谱技术可作为研究实际应用体系的重要工具 .     

Nanoscale Chemical Imaging of Interfacial Monolayers by Tip‐Enhanced Raman Spectroscopy

We report an investigation of interfacial fluorinated hydrocarbon (carboxylic‐fantrip) monolayers by nanoscale imaging using tip‐enhanced Raman spectroscopy (TERS) and density functional theory (DFT) calculations. By comparing TERS images of a sub‐monolayer prepared by spin‐coating and a π–π‐stacked monolayer on Au(111) in which the molecular orientation is confined, specific Raman peaks shift and line widths narrow in the transferred LB monolayer. Based on DFT calculations that take into account dispersion corrections and surface selection rules, these specific effects are proposed to originate from π–π stacking and molecular orientation restriction. TERS shows the possibility to distinguish between a random and locked orientation with a spatial resolution of less than 10 nm. This work combines experimental TERS imaging with theoretical DFT calculations and opens up the possibility of studying molecular orientations and intermolecular interaction at the nanoscale and molecular level.     

嵌段共聚物傅里叶变换拉曼光谱

用傅里叶变换拉曼光谱(FT-Paman)研究了聚环氧乙烷-聚环氧丙烷-聚环氧乙烷(PEO-PPO-PEO)嵌段共聚物的无水样品,发现某些谱带对PEO0-PPO-PEO嵌段共聚物的结构和构象变化敏感,其中某些峰的相对强度的PPO/PEO比率和共聚物的构象有关,研究表明PluronicF68和F88具有一些反式构象的螺旋结构,PluronicP103(P123)是无规则结构,其它的嵌段共聚物处于二者之间.     

Elucidating Peptide and Protein Structure and Dynamics: UV Resonance Raman Spectroscopy

UV resonance Raman spectroscopy (UVRR) is a powerful method that has the requisite selectivity and sensitivity to incisively monitor biomolecular structure and dynamics in solution. In this perspective, we highlight applications of UVRR for studying peptide and protein structure and the dynamics of protein and peptide folding. UVRR spectral monitors of protein secondary structure, such as the Amide III(3) band and the C(α)-H band frequencies and intensities can be used to determine Ramachandran Ψ angle distributions for peptide bonds. These incisive, quantitative glimpses into conformation can be combined with kinetic T-jump methodologies to monitor the dynamics of biomolecular conformational transitions. The resulting UVRR structural insight is impressive in that it allows differentiation of, for example, different α-helix-like states that enable differentiating π- and 3(10)- states from pure α-helices. These approaches can be used to determine the Gibbs free energy landscape of individual peptide bonds along the most important protein (un)folding coordinate. Future work will find spectral monitors that probe peptide bond activation barriers that control protein (un)folding mechanisms. In addition, UVRR studies of sidechain vibrations will probe the role of side chains in determining protein secondary, tertiary and quaternary structures.     

Chemical Applications of Raman Spectroscopy

Raman spectorscopy is—like infrared spectroscopy—a method for the study of vibrations of molecules and crystals. The two methods are complementary: if a vibration results in a change of the polarizability of a molecule, it is Raman active; if a change in the molecular dipole moment results, it is infrared active Vibrations of nonpolar groups and totally symmetrical vibrations of molecules are often only Raman active. IR and Raman spectra together give information about the symmetries and structures of molecules and crystals and about the properties of chemical bonds and intermolecular interactions. Until about 10 years ago Raman spectra could only be recorded on relatively large amounts of essentially colorless substances. After the advent of laser light sources the situation changed completely. The amount of sample substance required is now in the region of milli- and micrograms. Gases, liquids and solid samples, especially air-sensitive and reactive substances, single crystals, crystal needles and filaments as well as aqueous solutions can be readily investigated. The identification of molecules and the elucidation of molecular structures, biochemical analysis, and control of evnivornmental pollution are important aplications of Raman spectroscopy. Raman spectroscopy now constitutes an additional powerful tool in instrumental analysis     

PCT纳米材料结构相变的变温拉曼光谱研究

采用溶胶－凝胶法制备了（Ｐｂ１－ｘＣａ）ＴｉＯ３（ＰＣＴ（ｘ）纳米晶粉和纳米薄膜,变温拉曼光谱显示ＰＣＴ（０）和ＰＣＴ（２０）从铁电四方相向顺电立方相的转变温度分别降低至４３０℃和３３０℃;结果同时表明ＰＣＴ（０）和ＰＣＴ（２０）薄膜的声子频率发生一定程度的红移或蓝移,这归因于纳米材料掺杂引起的诱导效应和晶粒尺寸效应。     

Structure Analysis of Needle-like Copper Tantalum Trisulfide Crystals by XPS and Raman Spectroscopy

High-quality needle-like CuTaS3 single crystals have been synthesized through a chemical vapor transport(CVT)process.Crystallographic data show the special double chains of edge-sharing TaS6 octahedra....     

ENDOR Spectroscopy — A Promising Technique for Investigating the Structure of Organic Radicals

The name “ENDOR” has been known since biblical times and denotes a small town close to the Sea of Galilee (ca. 1000 B.C., 1 Sam. 28 : 7 ff). The acronym “ENDOR” (Electron Nuclear DOuble Resonance) characterizes the extension of electron spin resonance to electron-nuclear double resonance spectroscopy, a method that has opened up new dimensions for the investigation of complicated paramagnetic molecules. Only ENDOR spectoscopy, which has achieved technical perfection in the last decade, overcomes the resolution limitations of EPR spectroscopy, thus allowing interesting applications in the field of biochemistry. ENDOR investigations of the primary process of photosynthesis, of the mode of action of derivatives of vitamin E and K, and of the mechanism of the enzymatic catalysis of flavoenzymes in biological redox-chains have opened up new vistas. ENDOR and its extension to the triple resonance experiment TRIPLE offer, for example, the potential for a precise determination of hyperfine coupling constants, including their signs, which are frequently especially interesting. In addition to protons, a multiple of magnetic nuclei can be studied by ENDOR, such as e.g. ²H, ¹³C, and ¹⁴N. The ENDOR techniques is not restricted to monoradicals, but can also be applied to polyradicals in spin states of higher multiplicities (triplet, quartet, or quintet state). The experimental data accessible from ENDOR yield information about spin and charge density distributions, and about the geometrics of radicals and their internal dynamics; they also provide an excellent test for the accuracy of quantum mechanical calculations.     

二氧化钛系列光催化剂的拉曼光谱

采用溶胶-凝胶法制备了TiO₂粉体和薄膜光催化剂.使用FT-Raman光谱和激光共聚焦拉曼光谱研究了粉体和薄膜的拉曼光谱,探讨了热处理条件、Fe³⁺掺杂和以硅胶为载体的薄膜化所引起的TiO₂结构变化.结果表明,TiO₂在350℃存在由无定形向锐钛矿相的转变,600℃下存在锐钛矿相向金红石相的转变,750℃下完全转变为金红石相;掺杂会引起TiO₂的晶格畸变,导致拉曼谱峰宽化;以硅胶为载体的TiO₂负载薄膜的部分拉曼谱峰与粉体相比,有一定的位移和宽化.     

Excited-State Raman Spectroscopy of Inorganic Compounds

Abstract— Raman spectra of inorganic complexes in excited electronic states are discussed. A brief overview of the field of transient Raman spectroscopy and experimental considerations are presented. Two examples from the author's laboratory are used to illustrate the type of information that can be obtained. The first example, an excited-state Raman spectroscopic study of K₃[Mn(CN)₅NO], is chosen because it illustrates the connections between excited-state molecular structure and vibrational properties. The pump pulse causes a change from a linear sp-hybridized NO containing a triple bond to a bent sp²-hybridized NO containing a double bond. Both the NO stretch and normal modes involving other ligands are measured and interpreted. The second example is chosen to illustrate the vibrational consequences of photoinduced electron transfer. The Raman spectra of W(CO)₄(diimine) complexes (diimine = 2,2'-bipyridine, 4,4'-dimethyl-2,2'-bipyridine, and isopropyl-pyridine-2-carbaldehyde imine) in the lowest tungsten to diimine charge transfer excited state are discussed. The excited-state peaks are assigned to ligand ring deformation modes and to carbonyl stretching modes. The totally symmetric cis -carbonyl stretching mode in the charge transfer excited state is about 50 cm' higher in energy than that of the molecule in the ground electronic state. The increase is interpreted in terms of loss of metal-car-bonyl back-bonding in the charge transfer excited state. Finally, a summary of the field's strengths and difficulties and a brief discussion of the future perspectives are presented.     

氮气笼型水合物的激光拉曼光谱

在253K和16MPa的压力下,于实验室内合成了氮气水合物,用显微共焦拉曼光谱对其N-N和O-H键伸缩振动的光谱特征进行了研究．结果表明,氮气水合物中的N-N和O—H键的拉曼峰分别为2322．4和3092．1cm^-1,与天然的空气水合物中的数据十分接近．另外,还测定了液氮和溶解于水中的氮分子中N—N键的拉曼峰值,分别为2326．6和2325．0cm^-1．氮气笼型水合物分解的拉曼谱图表明,氮分子同时进入水合物的大笼和小笼中,但由于氮分子在大、小笼中的环境氛围十分接近,其拉曼位移相差不大,故拉曼谱图只能显示N—N键伸缩振动一个峰．     

硒化镉量子点膜的拉曼光谱及拉曼成像分析

研究了CdSe量子点膜的Raman光谱,发现CdSe量子点的横模(TO)振动活性较强,表面模(SO)、纵模(LO)振动不明显。比较了量子点、氧化三辛基膦及十六胺的Raman光谱,证明量子点表面大部分区域被十六胺及二辛胺修饰。在此基础上,对量子点膜的TO模振动及C-H弯曲振动峰进行了Raman成像分析,并与明场图像进行了对比,表明拉曼成像信号对量子点膜的表面变化非常敏感。     

Interfacial Water Structure in Langmuir Monolayer and Gibbs Layer Probed by Sum Frequency Generation Vibrational Spectroscopy

Langmuir monolayer and Gibbs layer exhibit surface‐active properties and it can be used as simple model systems to investigate the physicochemical properties of biological membranes. In this report, we presented the OH stretching vibration of H₂O in the 4′′‐n‐pentyl‐4‐cyano‐p‐terphenyl (5CT), nonadecanenitrile (C₁₈CN) Langmuir monolayer and compared them with CH₃CN Gibbs layer at the air/water interface with polarization SFG‐VS. This study demonstrated that the hydrogen bond network is different in the Langmuir monolayer of 5CT, C₁₈CN from CH₃CN Gibbs layer at the air/water interface which showed two different water structures on the different surface layer. The results provided a deeper insight into understanding the hydrogen bond on the interfaces.     

Investigating microcrystalline cellulose crystallinity using Raman spectroscopy

Cellulose - Microcrystalline cellulose (MCC) is a semi-crystalline material with inherent variable crystallinity due to raw material source and variable manufacturing conditions. MCC crystallinity...     

单晶电极界面反应过程的电化学原位拉曼光谱研究

自20世纪70年代起,人们利用原位光谱技术（拉曼、红外等）对电化学界面进行了系统的研究,进而发展出原位谱学电化学的研究方向,由于其具有良好的表面灵敏度和能量分辨率,可以提供更多的表面反应信息,进而从微观上揭示反应机理. 伴随着纳米技术的兴起,表面增强拉曼光谱技术取得了快速的发展. 近来,壳层隔绝纳米粒子增强拉曼光谱（shell-isolated nanoparticle-enhanced Raman spectroscopy,SHINERS）技术更是得到人们的广泛关注. SHINERS的出现为研究单晶模型电极上的催化反应提供了一种非常好的原位光谱技术. 本文主要对原位电化学SHINERS技术在单晶电极界面研究的具体应用及其发展前景进行相关论述.     

Probing Interfacial Electronic and Catalytic Properties on Well‐Defined Surfaces by Using In Situ Raman Spectroscopy

Heterogeneous metal interfaces play a key role in determining the mechanism and performance of catalysts. However, in situ characterization of such interfaces at the molecular level is challenging. Herein, two model interfaces, Pd and Pt overlayers on Au single crystals, were constructed. The electronic structures of these interfaces as well as effects of crystallographic orientation on them were analyzed by shell‐isolated nanoparticle‐enhanced Raman spectroscopy (SHINERS) using phenyl isocyanide (PIC) as a probe molecule. A clear red shift in the frequency of the C≡N stretch (ν_NC) was observed, which is consistent with X‐ray photoelectron spectroscopy (XPS) data and indicates that the ultrathin Pt and Pd layers donate their free electrons to the Au substrates. Furthermore, in situ electrochemical SHINERS studies showed that the electronic effects weaken Pt?C/Pd?C bonds, leading to improved surface activity towards CO electrooxidation.     

对巯基苯甲酸的表面增强拉曼光谱

应用表面增强拉曼光谱研究了吸附于粗糙银电极表面的对巯基苯甲酸。对巯基苯甲酸以去质子的形式通过巯基端进行吸附,表面Ag-S键的形成及羧基的结构改变直接影响苯环的电子结构。羧基的振动谱峰均对其质子化较为敏感,其峰强度随pH值的变化表明吸附态对巯基苯甲酸的pKa约为5．9。铜离子可与吸附对巯基苯甲酸形成表面络合物,配位反应与羧基的质子化反应密切相关。     

多孔β－TCP生物降解陶瓷的拉曼光谱

求文研究了多孔Ｂ－ＴＣＰ生物降解陶瓷及其粘结剂的拉王光谱。参照各种磷酸盐及磷酸盐玻璃的拉曼光谱，对生物降解陶瓷的拉曼特征频率进行了经验式的归属和指认。实验结果表明，生物降解陶瓷以β－Ｃａ３（ＰＯ４）２（β－ＴＣＰ）为主晶相，当粘结剂含量增加时，生物降解陶瓷中出现明显的Ｃａ４Ｐ２Ｏ９９和Ｃａ２Ｐ２Ｏ７，晶相和其他非晶相，其含量随粘结剂量增加而增加，并呈现一种多孔的网络结构。     

拉曼光谱技术在色谱分析检测中的应用

讨论了色谱分离与拉曼光谱检测的联用技术。表面增强拉曼光谱技术和紫外共振拉曼光谱技术克服了常规拉曼光谱技术所固有的灵敏度低的问题,所设计的与液相色谱联用的装置可以获取色谱柱流出液的拉曼光谱。评价了联用装置的重现性、动态范围和分析潜力,发现表面增强拉曼光谱仪和紫外共振拉曼光谱仪都可以作为薄层色谱、液相色谱法的检测器,可提供待测组分的结构信息,其灵敏度和其它常用检测器相似。