微过氧化酶的共振拉曼和表面增强拉曼光谱研究

采用电化学、共振拉曼和表面增强共振拉曼光谱研究了溶液态和吸附态微过氧化酶－１１（ＭＰ－１１）的电子传递及溶液和界面结构特征。结果表明,ＭＰ－１１在溶液中中心血红素铁以六配位状态存在,吸附于粗糙银电极表面时,则因ＭＰ－１１分子的重新取向而部分转化为五配位状态,氧化还原反应进一步促进这种配位状态的转化,并且配位状态也直接影响ＭＰ－１１的氧化还原性质。     

细胞色素bc_1复合物的共振拉曼光谱

对不同氧化还原状态的细胞色素 bc_1复合物的共振拉曼光谱进行了分析比较。对部分拉曼信号的变化进行了指认。细胞色素 c_1的还原引起1640cm~(_1)和1560cm~(_1)及1454cm~(_1)的明显变小,细胞色素 b 的还原引起1544cm~(_1)的下降。这些信号可以标志复合物中不同色素的氧化还原状态,对拉曼方法用于研究呼吸链酶系有重要参考价值。     

铁电极表面拉曼光谱的初步研究

本文成功地把表面 Raman光谱研究拓宽到重要的过渡金属之一的铁电极上。实验尝试了多种粗糙处理方法 ,如 :化学刻蚀、现场和非现场电化学氧化还原等法对铁电极表面进行处理 ,并首次获得吸附在粗糙铁电极上的吡啶分子的高质量表面拉曼光谱。经过比较发现表面拉曼光谱信噪比的提高与电极表面粗糙度有很大的关系 ,合适的表面粗糙度极有可能诱导出弱的表面增强拉曼散射效应     

纯钛电极上的表面增强拉曼光谱研究

采用机械粗糙、电化学氧化还原、化学刻蚀等方法对纯钛电极表面进行粗糙,在钛基底上获得了表面增强拉曼光谱(SERS)信号。初步的实验结果表明,采用机械粗糙和电化学氧化还原方法能够获得具有一定粗糙度的电极表面,但是该表面并不具有SERS活性。而采用氢氟酸化学刻蚀方法能够获得具有SERS活性的表面,并且成功检测到吡啶分子的表面增强拉曼信号。实验尝试了在不同条件下进行刻蚀,对酸的刻蚀浓度、刻蚀时间、外接电位等影响因素作了研究,结果发现基底的SERS活性随氢氟酸浓度增大而出现最佳条件,即氢氟酸浓度0.33 Wt%,刻蚀时间为5 min时的拉曼信号最好。实验以0.01 mol·L-1吡啶为探针分子,0.1 mol·L-1 KCl为电解质,在开路电位下成功地观察了钛电极上的表面增强拉曼光谱。     

还原态烟酰胺腺嘌呤二核苷酸拉曼光谱研究

还原态烟酰胺腺嘌呤二核苷酸(NADH)在维持细胞生长、分化、能量代谢以及细胞保护方面起着非常重要的作用,NADH的无创在体检测具有非常重要的意义。运用激光拉曼散射实验和密度泛函理论(DFT)计算研究了200～3 300 cm-1光谱范围内NADH分子的振动模式特性。DFT计算采用了B3LYP杂化方法,并选用了极化6-311+G(d,p)基组。为了准确的分析NADH分子的振动模式和频率,首先运用B3LYP/6-311+G(d,p)理论对NADH分子的基态结构进行了几何优化,并计算了基态结构NADH分子的各个键长和键角。同时考虑到DFT计算中的非谐性,运用波数线性标度方法对所有计算所得振动模式波数重新进行了标度。重新标度后,DFT计算所得的振动模式波数与激光拉曼散射实验观测到的拉曼峰波数吻合的很好：在200～3 300 cm-1整个光谱范围内,计算与实验结果具有非常好的线性相关性,而且大部分振动模式的计算与实验之间的偏差都小于5 cm-1。此外,讨论了实验观察所得拉曼光谱的分子振动模式归属,分析了NADH分子中腺嘌呤、烟酰胺、及二核苷酸的特征振动模式,并初步提出了运用拉曼光谱实现NADH快速准确无创在体检测的方法。位于732 cm-1处的拉曼峰是腺嘌呤的特征振动模式,而且可以选为检测NADH分子的最特征拉曼峰。位于1 690 cm-1处的拉曼峰是烟酰胺的特征振动模式,可以选为进一步准确检测NADH分子的另一个特征拉曼峰。位于1 086和1 339 cm-1两处拉曼峰的组合可以作为二核苷酸的特征振动模式,用于进一步更准确的检测NADH分子。所以在运用拉曼光谱法实现NADH快速准确无创在体检测时,可以首先运用位于732 cm-1处NADH分子的最特征振动模式进行快速检测,然后再运用位于1 690 cm-1及1 086和1 339 cm-1组合等特征振动模式进行准确分析。     

现场拉曼光谱研究多种铂氧化物还原过程及其对甲醇氧化的影响

采用原位拉曼光谱技术研究方波电位循环氧化还原 (ORC)过程中产生的铂氧化物的还原过程 ,其中过氧化物和超氧化物消失的电位在 0 2V左右 ,晶格氧化物和氧化铂则分别消失在 0V和 -0 2 5V左右。我们还初步探讨了不同还原电位下形成的铂电极表面纳米微粒对甲醇电催化活性的影响     

飞秒强激光对二氧化钛金红石晶体相变的影响

该文章报道了利用显微激光拉曼光谱仪研究近红外飞秒强激光脉冲诱导二氧化钛金红石单晶所引起的相变.实验辐照时间为60s,当激光辐照平均功率增加时,锐钛矿相的拉曼振动模式强度增强,金红石相的拉曼振动模式强度减弱.通过金红石相和锐钛矿相粉体等拉曼光谱的实验,肯定了随着辐照激光功率的增大,.可以通过拉曼光谱中锐钛矿A1g B1g(515 cm-1)振动模式标志峰和金红石相Eg(445 cm-1)振动标志峰分别对应面积的比判断其相变量.     

非水体系中镍表面Raman光谱研究新进展

本文利用共焦显微拉曼系统 ,获得有机乙醇溶剂中吡啶分子吸附在硝酸刻蚀镍电极表面的拉曼光谱 ,与水体系相比谱峰强度有所降低。根据表面拉曼光谱中吡啶分子环呼吸振动峰 ν1向高波数方向移动 (与液态吡啶分子相比 )推测吡啶分子通过氮原子以垂直 (或略微倾斜 )方式作用于镍电极表面 ,且随电位负移其与镍表面的作用逐渐减弱。     

溶剂折射率对β-胡萝卜素拉曼散射截面的影响

以环己烷的1444 cm^-1拉曼线为内标,采用5145 nm激发光分别测量了β-胡萝卜素的C=C双键（1520 cm^-1）和C—C单键（1155 cm^-1）振动模式下在不同折射率溶剂中的拉曼散射截面,结果表明随溶剂的折射率增加β-胡萝卜素在两种振动模式下拉曼散射截面都增加.利用色散力和共振拉曼理论解释了在不同折射率溶剂中β-胡萝卜素散射截面的差异. 关键词： 拉曼散射截面 β-胡萝卜素 色散力 共振拉曼     

DFT理论探讨银电极表面吸附吡啶和水分子的表面增强拉曼光谱

本文利用密度泛函方法计算了吡啶和水分子分别吸附于粗糙银电极表面的拉曼光谱强度。结果表明,在不发生共振拉曼散射情况下,拉曼强度随电极表面负电荷量的增加而显著增大。理论预测与实验结果一致。     

Raman and surface‐enhanced Raman spectra of flavone and several hydroxy derivatives

The Raman and surface‐enhanced Raman spectra (SERS) of flavone and three of its hydroxy derivatives, 3‐hydroxyflavone (3‐HF) and 5‐hydroxyflavone (5‐HF) and quercetin (3,5,7,3′,4′ pentahydroxyflavone) have been obtained. The normal Raman (NR) spectra were taken in the powder form. The SERS spectra were obtained both on Ag colloids and Ag electrode substrates. Assignments of the spectrally observed normal modes were aided by density functional theory (DFT) calculations using the B3LYP functional and the 6‐31 + G* basis, a split valence polarized basis set with diffuse functions. Excellent fits were obtained for the observed spectra with little or no scaling. The most intense lines of the NR spectra are those in the CO stretching region (near 1600 cm⁻¹). These lines are often weakened by proximity to the surface, while other lines at lower wavenumbers, due to in‐plane ring stretches, tend to be strongly enhanced. The SERS spectrum of flavone is weak both on the colloid and on the electrode, indicating weak attachment to the surface. In contrast, the SERS spectra of the hydroxy derivatives of flavone are intense, indicating the assistance of OH groups in attachment to the surface. The spectra of the various species are compared, and a case study of application to detection of a textile dye (Persian berries), which contains quercetin, is presented. Copyright © 2007 John Wiley & Sons, Ltd.     

3.4% NaCl介质中铁点蚀行为的表面拉曼光谱成像研究

本文利用共焦拉曼光谱技术结合对铁电极的合适的粗糙化预处理,现场研究了３．４％ＮａＣｌ腐蚀介质听电极的点蚀行为,获得了点蚀坑内腐蚀产物的表面增强拉曼光谱,成功地将表面增强拉曼光谱技术拓宽至铁的腐蚀行为的研究中,利用共焦拉曼光谱仪的成像技术研究了位于６６０ｃｍ＾－１处点蚀产物的二维分布图。研究表明：在校正电位铁表面发生点蚀后,点蚀坑内腐蚀产物不是以单一物种存在,而是多种铁氧化合物共存,且这些铁的氧化腐蚀产物的点蚀坑内的分布也极不均匀。     

银电极表面上C60薄膜的表面增强拉曼光谱研究

在银电极表面形成一层C60薄膜,分别在乙腈溶液和水溶液中进行表面增强拉曼光谱(SERS)研究并将两者进行比较,从而消除了溶液中的C60干扰表面吸附C60的SERS谱图的可能性.研究结果表明,C60分子对称性的降低导致SERS谱峰发生了分裂;表面电磁场的作用使得光谱选律在SERS效应中被拓宽,产生了新的拉曼谱峰.该结果与团簇吸附在粗糙银电极表面的C60分子的研究结果相似.与之不同的是在乙腈溶液和水溶液中的SERS谱图的低波数区内分别在348和311 cm-1左右出现一个新峰,经过分析可认为该峰与C60-金属基底的相互作用有关.     

Electrochemical in situ surface enhanced Raman spectroscopic characterization of a trinuclear ruthenium complex,Ru‐red

To study the fate of a molecular di‐μ‐oxo‐bridged trinuclear ruthenium complex, [(NH₃)₅Ru–O–Ru(NH₃)₄–O–Ru(NH₃)₅]⁶⁺, also known as Ru‐red, during the electro‐driven water oxidation reaction, electrochemical in situ surface enhanced Raman spectroscopy (SERS) investigations have been conducted on an electrochemically roughened gold surface in acidic condition. It was previously described that on a basal plane pyrolitic graphite electrode in 0.1 M H₂SO₄ aqueous solution, Ru‐red undergoes one electron oxidative conversion into a stable higher oxidation state ruthenium complex, Ru‐brown, at <1.0 V (vs normal hydrogen electrode (NHE)), and this leads to water oxidation and dioxygen release, but the fate of Ru‐red during electrochemistry was not studied in much detail. In this investigation, Ru‐red dispersed in acid electrolyte and immobilized on a roughened gold electrode without Ru‐red in solution has been subjected to anodic controlled potential experiments, and in situ SERS was carried out at various potentials in succession. The electrochemical SERS data obtained for Ru‐red are also compared with in situ SERS results of an electrodeposited ruthenium oxide thin film on the Au disk. Our study suggests that on a gold electrode in sulfuric acid solution containing Ru‐red, one electron oxidative conversion of Ru‐red to a higher oxidation state ruthenium compound, Ru‐brown, occurs at ca. 0.74 V (vs NHE), as supported by the electrochemical in situ SERS experiments. Moreover, at higher potentials and on Au disk, the Ru‐red / Ru‐brown are not stable and slowly decompose or electro‐oxidize leading to deactivation of the tri‐ruthenium catalytic system in acidic medium. Copyright © 2013 John Wiley & Sons, Ltd.     

Substituent effect on structure and surface activity of N‐methylpyridinium salts studied by FT‐IR,FT‐RS,SERS and DFT calculations

The substituent effect on structure and surface activity of mono‐ and disubstituted N‐methylpyridinium salts was investigated by means of Raman, infrared and surface‐enhanced Raman spectroscopy (SERS). The significant differences observed in Raman and infrared spectra have been correlated with marker bands assigned to in‐plane and out‐of‐plane vibrations, respectively. This vibrational analysis, complemented by quantum chemical calculations (B3LYP/6‐311++G(d,p)) was a basis for investigation of the surface activity of the studied compounds. Significant differences in their SERS spectra related to the enhancement mechanism and adsorbate orientation have been observed and analyzed. Copyright © 2012 John Wiley & Sons, Ltd.     

哌啶分子在两种不同银电极上吸附行为的实验和理论研究

分别在粗糙银电极和银纳米颗粒修饰银电极上得到了哌啶分子的表面增强拉曼（SERS）光谱。哌啶在银电极与银纳米颗粒修饰的银电极上的SERS谱有很大的区别,分析认为是由于哌啶在不同基底上的吸附方式不同所引起的,据此建立了哌啶吸附在银颗粒表面的两种模型,用DFT-B3PW91-lanl2dz方法计算了两种模型的拉曼频移,通过与实验结果比较说明了哌啶分子主要通过N原子的孤对电子竖直吸附在粗糙银电极表面,而在银纳米颗粒修饰的银电极上则以平行吸附方式为主。     

SERS as a probe for adsorbate orientation on silver nanoclusters

Surface‐enhanced Raman scattering (SERS) spectroscopy has been used to characterize multilayers of three isomeric aromatic compounds adsorbed on silver nanoclusters. The three structural isomers, all of which adsorb in the carboxylate form onto the silver nanoclusters, bind in two different geometries to the silver surface. Different molecular configurations correlate to differences in bonding strength of these molecules to the silver surface, which can be probed by SERS. For ortho‐hydroxybenzoic acid (salicylic acid), we observed red shifts of major SERS peaks in comparison to the normal Raman vibrations of nonadsorbed crystalline material. For this molecule the steric hindrance between the adjacent carboxylate and hydroxyl groups causes the carboxylate group to rotate from the common flat geometry of benzene substituents on surfaces and bond directly through one of the oxygen atoms to the surface. In this case, strong coordinative bonding between the carboxylate group and the metal surface causes the red shifts in the SERS peaks. For para‐, and meta‐hydroxybenzoic acid, the steric hindrance is less likely since the two functional groups are not at adjacent positions, and therefore these molecules adsorb on the silver surface in a totally flat geometry. For these molecules, in contrast to the ortho isomer, the CO₂ interacts with the surface through an extended π bond, and these molecules are physically adsorbed in the common flat position. Therefore, for the meta and para substituents, we do not observe significant red shifts in the SERS spectrum. Copyright © 2009 John Wiley & Sons, Ltd.