硫脲在HNO3介质中共吸附行为的喇曼光谱研究

用常规Raman谱、电化学现场表面增强喇曼散射光谱(SERS)和时间分辨SERS光谱(TRSERS)研究了硫脲(TU)在HNO₃介质中与NO-3的共吸附行为.实验结果表明,NO₃^-离子能被TU诱导共吸附在其质子化氨基上;TU以S端按σ配位键方式化学吸附在银电极表面.在较正电位区间(≥-0.6V),TU垂直吸附,电位负移(≤-0.8V),TU由垂直逐渐转变为倾斜甚至平躺吸附;在较负的电位下(≤-0.8V),TU在HNO₃介质中比在HClO₄中更稳定,甚至在-2.0V的电位下亦能检测到TU的SERS信号.     

电极表面Ag(δ+)-NH3络合物的表面增强拉曼散射效应

本文采用氧化还原循环处理电极首次得到Ag/0.1 mol L~(-1)NH_3+0.1 mol L~(-1)NH_4Cl体系中吸附在银电极上氨分子的表面增强拉曼散射(SERS)效应。按氨分子在电极表面上的吸附量为每平方厘米8×10~(15)计算, 增加因子为1.2×10~5。谱峰强度及位置随电极电位改变。吸附氨分子的SERS谱与Ag(NH_3)_2~+的正常拉曼光谱类似。本文结果表明电极表面上存在Ag(δ+)络合物, 它可能是SERS效应的活性中心, 用这个概念可较好地解释本文实验结果。通过谱图分析给出了Ag(δ+)表面络合物的可能结构模式。     

电极表面Ag(δ+)-NH_3络合物的表面增强拉曼散射效应

本文采用氧化还原循环处理电极首次得到Ag/0.1mol L~(-1)NH_3+0.1mol L~(-1)NH_4Cl体系中吸附在银电极上氨分子的表面增强拉曼散射(SERS)效应。按氨分子在电极表面上的吸附量为每平方厘米8×10~(15)计算,增加因子为1.2×10~5.谱峰强度及位置随电极电位改变。吸附氨分子的SERS谱与Ag(NH_3)_2~+的正常拉曼光谱类似。本文结果表明电极表面上存在Ag(δ+)络合物,它可能是SERS效应的活性中心,用这个概念可较好地解释本文实验结果。通过谱图分析给出了Ag(δ+)表面络合物的可能结构模式。     

胞嘧啶吸附在粗糙金电极上的表面增强拉曼光谱

应用电化学伏安法和表面增强拉曼光谱(SERS)研究在-1.0 V~0 V电位区间内胞嘧啶于粗糙金电极表面的吸附行为.结果表明,在本实验的电位区间,胞嘧啶是以其N3位垂直吸附在粗糙金电极表面的.在负电位区间环呼吸振动模的强度出现极大值,与其它振动模强度相比,作者认为电磁场的增强和电荷转移均使该谱峰的拉曼信号增强.胞嘧啶的环呼吸振动频率随着电位负移而红移,这意味着它与金电极的成键作用减弱.同时也表明SERS谱可用于研究生物分子在金属电极表面的吸附行为.     

表面等离激元增强金属光致发光助力表面增强拉曼光谱获取表界面分子的本征化学信息

<正>表面增强拉曼光谱(SERS)因其具有单分子的检测灵敏度和特异的分子指纹信息,在表面科学和分析检测领域得到广泛关注~1。拉曼光谱研究中除了利用谱峰频率外,还利用不同谱峰间的相对强度,以获得吸附分子的吸附构象、分子与金属界面电荷转移、材料局域化学性质等多种重要物理化学信息。然而在SERS中,贵金属纳米结构的局域表面等离激元共振(LSPR)不仅增强了样品的拉曼信号的绝对强度,也改变了SERS谱图中不同谱峰的相对强度,即不同频率的拉曼信号受到的增强作用不同,从而导致用SERS峰的相对强度所获得的样品的物理化学信息变得不可靠。虽     

自组装DNA吸附取向的表面增强拉曼光谱法研究

对金基体上自组装寡聚核苷酸探针杂交前后进行电化学非现场及现场表面增强拉曼光谱(SERS)研究.非现场SERS研究表明,杂交形成的dsDNA在基体表面以A型和B型两种构象同时存在,杂交过程可能伴随DNA链在基体表面吸附取向的变化.根据现场SERS研究结果可知,ssDNA及dsDNA的大多数SERS谱带强度随电极电位正移而降低,尤其是归属于碱基A的两种面外振动模式,谱带变化更为明显.利用SERS表面选择定则判断出随着电极电位由负向正变化,ssDNA及dsDNA螺旋吸附取向由垂直吸附向平躺吸附于金基体表面变化.     

水在Ag电极上取向与结构的SERS研究──不同电极电位和NaClO4浓度的影响

将特殊的ORC方法、薄层溶液技术和差谱方法相结合,在较宽的电位区间(-0.7-2.0V),获得了不含任何(类)卤素离子的NaClO₄/Ag体系中水的SERS谱.结果表明,不同浓度的NaClO₄体系中,尽管体相水的结构有很大差别,但电极表面的吸附水有相似的结构特征,即由于电场作用而使有序性较高;并且随电极电位由极负电位向零电荷电位(PZC)变化时可能都经历着由单氢端吸附转变为双氢端吸附,继而又转向氧端吸附的取向变化过程.利用SERS技术特有的检测表面物种的高灵敏度,可观察到NaClO₄浓度引起的表面水的SERS谱的一些细微差异,依此较详细讨论了NaClO₄浓度对表面水的结构和取向变化过程的影响.     

吡啶-氯化钾水溶液/n型硫化镉电极界面上的表面增强喇曼散射

本文研究了在吡啶-KC1水溶液中吡啶吸附在n-CdS电极上的表面增强喇曼散射(SERS)。在光照下,CdS电极经过正极化予处理数分钟,就能观察到吡啶吸附在CdS电极上的很强的SERS谱。其特征峰是1010和1036cm^-1与纯吡啶的喇曼特征峰991,1030cm^-1相比有了明显位移。又SERS谱随着吡啶浓度的增加而增强。外加电位对SERS也有一定影响,其曲线形状与CdS的I～V曲线很相似。对这些实验结果,本文用n型CdS电极的光电化学特性进行了初步的考察和讨论。     

表面增强拉曼光谱内标法测定水杨酸浓度

采用电化学方法处理银电极表面,使之产生具有表面增强拉曼光谱(SERS)的活化效应,进而利用水杨酸(SA)吸附于粗糙活化的银电极表面所产生的SERS光谱,进行SA含量的测定。选择硫氰化钾(KSCN)为内标物,以SA的苯环呼吸振动峰(1 036 cm-1)与SCN-的特征峰(2 120 cm-1)强度比值作为相对强度,其相对强度与水杨酸的浓度在4×10-6~3×10-4mol/L范围内呈良好的线性关系,其线性系数为0.993 1;检出限为2.04×10-6mol/L;加标回收率为85.4%~114.6%。方法具有测定简便、内标物干扰小、绿色无害等特点,可进一步推广于其他特殊物质的测定。     

甲酸在Aucore@Ptshell/Pt电极上电催化氧化的原位SERS

用化学还原法合成了Aucore@Ptshell纳米粒子, 并用扫描电子显微镜(SEM)及X射线衍射(XRD)等技术对纳米粒子进行表征; 采用电化学原位表面增强拉曼光谱(SERS)技术对甲酸的电催化氧化过程进行了研究, 成功地获得了甲酸在Aucore@Ptshell/Pt电极上解离吸附的原位SERS. 结果显示, 在开路电位时, 甲酸能在Aucore@Ptshell/Pt电极表面自发氧化, 解离生成强吸附中间体COad和弱吸附中间体HCOOad, 在电位为+0.10 V时检测到氧化产物CO2的谱峰. 研究结果表明, Aucore@Ptshell/Pt电极对甲酸的氧化具有较高的催化活性和较强的SERS效应, 甲酸在Aucore@Ptshell/Pt电极上的电催化氧化过程遵循双途径机理.     

SERS study of the interaction of thiourea with a copper electrode in sulphuric acid solution

The electrochemical interaction of thiourea with a copper electrode in sulphuric acid solution was investigated using Fourier transform Raman and in situ surface-enhanced Raman scattering (SERS) spectroscopy. SERS spectra of thiourea at a copper electrode were obtained in solutions containing greater than 5 ppm thiourea; the spectra obtained were consistent with adsorption of the molecule on the copper electrode via the sulphur atom. The SERS spectra provide evidence of complex formation involving thiourea and sulphate species at the electrode surface.     

银电极表面异亮氨酸单分子膜结构和表面性质的表面增强拉曼光谱研究

利用表面增强拉曼光谱(SERS)技术研究了在粗糙化银电极表面吸附的异亮氨酸自组装单层膜结构及其表面性质随溶液酸碱性和电极电位改变的特征.研究结果表明溶液pH值的变化并没有显著改变异亮氨酸分子在银电极表面以去质子化羧基吸附为主的特征.借助于高氯酸根离子这一SERS光谱探针,对异亮氨酸单分子膜的表面酸碱性质进行了表征和分析.而就电位改变对该单分子膜结构的影响而言,在所研究的电位范围内,单分子膜中的异亮氨酸分子是通过去质子化羧基与氨基两个位点而吸附的,且吸附作用随电位负移而呈现有规律的变化.     

苯胺在银和金电极上的表面增强拉曼光谱

聚苯胺作为性能较好的导电高聚物有很大的应用潜力,有关其聚合和导电机理的研究受到广泛重视。表面增强拉曼光谱(SERS)能现场(in situ)检测表面吸附分子、提     

Orientation of 6-mercaptopurine SAMs at the silver electrode as studied by Raman mapping and in situ SERS

Self-assembled monolayers (SAMs) of 6-mercaptopurine (6MP) on a silver electrode in acid and alkaline media were investigated by a combination protocol of the SERS technique with Raman mapping, and it was found that the adsorption mode of 6MP SAMs changed with the pH value of the environment. Quantum calculations for the vibrational mode were performed by the BLYP/6-31G method. 6MP was adsorbed on the silver electrode with a tilted orientation via S, N1, and N7 atoms in acid medium, while the SAMs adopted head-on adsorption modes with the S atom and the N1 atom anchoring the silver surface in alkaline medium. However, 6MP SAMs turned to the same upright orientation on the electrode through the S and N7 atoms when either acid or basic solution was removed. Stability of 6MP SAMs was observed by in situ SERS spectroelectrochemical measurements. The results reveal that the desorption potentials of 6MP SAMs formed under acid and alkaline conditions from the Ag electrode were at ca. -1.3 V and -1.6 V vs SCE, respectively.     

Temporal Response of SERS to the Potential for 4-Cyanopyridine Adsorbed on Ag Electrode

Time-resolved surface-enhanced Raman scattering (SERS) was applied to study the response of Raman bands from 4-cyanopyridine (PyCN) adsorbed on a Ag electrode to variation of the potential; the temporal resolution was 0.1 s. The response of the SERS signals of PyCN was instantaneous to the oxidation potential of Ag electrode. However, delay of the SERS signals was observed while AgCl was reducing. The decay and growth of the SERS bands look place within 1 s in the cases of desorption and adsorption of PyCN on the electrode. It took much longer for PyCN to alter from one adsorption geometry to another on the electrode.     

硫脲及其衍生物的SERS和量子化学研究

Adsorption of thiourea (TU) and ethylthiourea(ETU) on roughened silver electrode was investigated using in- situ surface enhanced Raman spectroscopy(SERS). Using quantum chemistry and HSAB theories, the influences of electrode potential and the different substituent groups on SERS were discussed. TU is chemisorbed perpendicularly by Ag-S bond on silver at E=-0.3 V and adsorption of TU turns into a parallel orientation at E=-0.9 V. ETU is always chemisorbed at an angle from Ag. The adsorption of ETU is through C=C and C=O groups at E=-0.3 V, and mainly through C=C at E=-0.9V.     

Raman Spectroscopic Studies on the Complexation and Adsorbed Behaviour of Thiourea

Raman spectroscopic studies on thiourea (TU) in highly acidic media (e. g. >3 mol/L HC1O4) show that TU as a solution species is protonated through its sulphur atom and forms complex with anions. However, as an adsorbed species, TU is protonated via the nitrogen atom and adsorbed at the silver electrode surface through the sulphur atom. The distinct effects of pH and anions of the solution on the surface enhanced Raman (SER) spectra of TU were investigated. In acidic and neutral solutions, TU is coadsorbed with anions through its NH3 and - NH2 groups respectively.     

增感染料1556、798吸附在银电极上的表面增强拉曼光谱

本文利用表面增强拉曼光谱研究了增感染料1556、798在银电极上的吸附,通过比较染料的固体拉曼光谱和染料的表面增强光谱,我们发现两种染料在银电极表面的吸附行为不完全相同,吸附时染料分子的平面基本上与电极表面相垂直。