Cu,Zn-SOD在银电极上的原位表面增强Raman光谱

本文应用原位共焦拉曼光谱技术观察了Cu ,Zn -SOD分子在经表面增强处理后的银电极上 ,吸附状态随电位跃迁变化的过程。结果表明在 -0 2V～ 0 1V的电位区间内 ,Cu,Zn -SOD分子经由羧酸根离子吸附于银电极表面 ,而在 0 2～ 0 4V电位区间内发生脱附 ,表面吸附的物种改变为缓冲溶液中的磷酸根离子。上述结果为SOD分子在固体电极表面电子传递机制的探索提供了依据。     

半胱胺单分子膜结构的表面增强拉曼散射研究(英文)

在金属电极表面所形成的有机分子的单分子膜或薄膜对于基础研究和实际应用都有着极其重要的意义。以化学吸附形式在金电极表面所形成的半胱胺单分子膜,常常用于蛋白质等生物大分子在金属表面进行吸附的连接层,以避免这些生物大分子在金属表面直接吸附而造成的变性、失活现象的发生。本文报道了我们采用表面增强拉曼散射光谱方法研究在金电极表面吸附的半胱胺单分子膜的结构特征。研究结果表明,在金电极表面所形成的半胱胺单分子膜中,半胱胺分子主要的构型为扭转构型。在与金表面的相互作用中,由于除巯基的结合作用以外,还存在半胱胺分子中端基氨基和金表面较强的亲和性,使得以扭转构型吸附在金表面的半胱胺单分子膜相当稳定。这是金电极表面的半胱胺单分子膜结构的主要行征。当考察外加电势对此单分子膜结构的影响时,可以发现有关扭转构型的特征谱峰其相对强度随着电位负移而减小。这一结构随电位的变化关系可以通过表面电势的变化对氨基氮原子上孤对电子与金属表面间相互作用的影响来加以阐释。     

电化学体系中吸附在金电极表面吡啶的紫外拉曼光谱研究

观察到波长为325nm的紫外光激发下吸附在金电极表面的吡啶的表面增强拉曼光谱(SERS)。结合其SERS谱随电位的变化关系,分析了其中的增强机制并表明随电位的负移吡啶的吸附方式发生改变。     

胞嘧啶吸附在粗糙银和金电极上的表面增强拉曼光谱

利用电化学伏安方法和表面增强拉曼光谱(SERS)技术研究了在-1.0V~0V的电位区间内胞嘧啶在粗糙银电极和金电极表面上的吸附行为。结果表明,在所研究的电位区间,胞嘧啶通过N3位垂直吸附在粗糙银和金电极表面,且当电位负移时吸附作用减弱。     

吡啶羧酸在银电极表面随电极电位变化的表面增强拉曼光谱研究(英文)

本文通过表面增强拉曼散射研究了三种不同构型的吡啶羧酸—皮考酸、异烟酸和烟酸在粗糙银电极表面上的吸附形态随电极电位的变化关系。大量的表面结构信息可从丰富的表面拉曼信号及其随电极电位相应的变化而获得。分析表明在电极电位负移过程中皮考酸分子一直采取通过羧基和苯环上的N原子侧立吸附在银电极表面,与之不同的是,异烟酸分子和烟酸分子在表面的吸附状态都随电位改变发生了变化,我们对此进行了分析和解释     

3种核酸碱基(胞嘧啶、胸腺嘧啶、尿嘧啶)在银电极表面的吸附形态

通过表面增强拉曼散射研究了胞嘧啶、胸腺嘧啶和尿嘧啶在粗糙银电极表面上的吸附形态随电极电位的变化关系.大量的结构信息可从丰富的表面拉曼信号及其随电极电位相应的变化而获得.分析表明在电极电位负移过程中,胞嘧啶一直通过N3位垂直吸附于纳米银颗粒表面;而胸腺嘧啶分子和尿嘧啶分子在表面的吸附状态都随电位改变发生了变化,较正电位下...     

现场拉曼光谱研究乙腈在金电极上的解离吸附行为

利用共焦显微拉曼系统、结合合适的电极表面粗糙方法研究了非水体系 0 1mol/LLiClO4 /CH3CN溶液中 ,乙腈分子在金表面的吸附和解离行为。结果表明非水体系中乙腈可在金表面发生还原反应 ,产物CN- 离子与电极表面作用形成的表面配合物可在较宽的电位区间吸附于电极表面。溶液中的微量水、激光照射以及电极电位均对该反应有较大的影响。通过拉曼谱图的比较得出乙腈分子解离出的CN- 在金电极表面比在银电极表面有更强的吸附作用。     

苯并三唑表面配位化学的电化学现场拉曼光谱研究

用电化学现场表面增强拉曼光谱(SERS)研究了非水体系中苯并三唑(BTAH)在银电极表面的吸附及成膜行为,结果表明非水体系中BTAH的吸附行为随电位变化而不同。较负区间主要以中性分子形式吸附;中间电位区间主要以BTA-吸附并不可逆成膜。采用直接电化学合成技术模拟电极表面过程制备了苯并三唑与Cu, Ag, Fe, Ni和Zn等金属的配合物,并研究了中性配体三苯基膦(pph₃)对其配位过程的影响,所得产物的元素分析以及拉曼光谱研究表明pph₃的加入影响了Cu和Ag与BTAH的配位过程,并出现在最终产物中,而对BTAH与Ni, Fe和Zn的配位过程未产生影响,产物未出现pph₃。     

非水体系中吡啶和乙腈在铂电极上竞争吸附的表面增强拉曼光谱研究

继非水体系中CO在过渡金属表面吸附的表面增强拉曼光谱（SERS）研究之后，本文是又一篇关于非水体系中过渡金属表面SERS研究的文章。从拉曼谱峰的变化结果发现，吡啶在Pt电极表面是强烈的化学吸附，并且由于其吸附的量和吸附取向随电位在不断地变化，与水体系中吡啶（Py)在Pt电极表面的吸附相比较，SERS谱峰除了强度较低之外，在可研究的电位区间、谱峰位置以及其随电位变化等方面都存在着不同，这缘于结构较为复杂的有机溶剂分子在电极表面组成了更为复杂的界面结构，造成固／液界面的电迁移等电极动力学过程发生了变化，为了说明这一现象，文中还采用强吸附离子I^-进行研究，得到相似的结果。     

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。     

Stripping voltammetry of Pb and Cu using a microcantilever electrode

Microfabricated silicon microcantilevers coated with gold on one side have been used as working electrode in a three-electrode electrochemical arrangement. In addition to electrochemical current, cantilever bending has been used as a signal for monitoring electrode reactions on the cantilever surface. The microcantilever bending was measured by an optical beam deflection method as the surface potential was scanned and electrochemical reactions occurred on the surface. The microcantilever bending due to differential surface stress was used to sense Pb and Cu using cyclic voltammetry (CV) and linear sweep stripping voltammetry (LSSV).     

咪唑在铜电极上吸附行为的SERS研究

咪唑在铜电极上吸附行为的ＳＥＲＳ研究张传飞，徐知三，旷富贵，王小华，刘海林（武汉大学分析测试中心武汉４３００７２）（武汉大学环境科学系武汉４３００７２）ＳｔｕｄｙｏｎＴｈｅＡｄｓｏｒｐｔｉｏｎＢｅｈａｖｉｏｕｒｏｆＩｍｉｄａｚｏｌｅｏｎＣｏｐｐｅｒＥ...     

Effect of ground electrode on charge injection and surface potential of corona charged polyethylene film

The surface potential decay measurement is a simple and low cost tool to assess electrical properties of insulation materials; therefore, understanding the physical mechanisms of the surface potential decay becomes necessary. With our recent space charge measurement results on corona charged samples, bipolar charge injection on corona charged samples had been observed. Based on this new fact, it is anticipated that the ground electrode should have significant effect during corona charging and subsequently decay processes. In the paper, low density polyethylene (LDPE) film with gold ground electrode was compared with LDPE film with aluminium ground to study effect of ground electrode on charge injection and surface potential decay processes. Charging current during the corona charging, surface potential decay and space charge dynamics after corona charging in the samples with either gold coated or aluminium ground electrode were measured. Differences have been observed for gold ground electrode when compared with aluminium ground electrode. Higher work function of gold electrode is responsible for the observed differences. A preliminary simulation has also attempted to show that the bipolar injection may take place in corona charged LDPE films.     

Heterogeneity of surface potential in contact electrification under ambient conditions: A comparison of pre- and post-contact states

We measured the pattern of charging by contact electrification, following contact between a polydimethylsiloxane (PDMS) stamp and a glass substrate with gold electrodes. We used scanning Kelvin probe microscopy to map the surface potential at the same regions before and after contact, allowing a point-by-point comparison. After contact, the mean surface potential of the glass shifted by 360 mV and micron-scale heterogeneity appeared with a magnitude of ∼100 mV. The gold electrodes showed charge transfer but no discernible heterogeneity. These results show that contact electrification causes heterogeneity of surface potential even on non-polymer surfaces such as glass under ambient conditions.     

Potential-induced structure transitions in self-assembled monolayers: ethanethiol on Au(1 0 0)

We have characterized the structural behaviour of ethanethiol self-assembled monolayers (SAMs) on Au(1 0 0) in 0.1 M H₂SO₄ as a function of electrode potential, using in-situ scanning tunneling microscopy (STM). After modification of the Au(1 0 0) electrode in an ethanolic solution of ethanethiol, STM images in air reveal a disordered thiol adlayer and a surface that is covered by 25% of monoatomic high gold islands, which originate from lifting of the (hex) reconstruction during thiol adsorption. In contrast to alkanethiol SAMs on Au(1 1 1), no vacancy islands are seen on the Au(1 0 0) surface. After contact of the SAM-covered Au(1 0 0) electrode with 0.1 M H₂SO₄ under potential control, two different structures are observed, depending on the potential range positive or negative of +0.3 V vs. SCE. In both cases the emerging ordered structures are quadratic, their unit cells being rotated by 45° with respect to the main crystallographic axes of the substrate. However, the ordered structure at negative potentials is more densely packed than the one at positive potentials, and in addition the surface reveals an almost 50% coverage of monoatomic high gold islands. The structure of the SAM changes reversibly with the electrode potential, the long range order gradually decreasing with each transition. Concomittant with this structure transition monoatomic deep holes are created when the potential is stepped from the cathodic to the anodic region. The experimental observations are rationalized by a high mobility of the gold thiolate moiety, causing the surface density of the SAM-covered gold to change drastically with potential.     

Anisotropy of the surface properties of germanium in contact with an electrolyte containing gold ions

Recombination curves and polarization curves as well as the differential capacitance of an interface layer and the deflection of energy-band surfaces as functions of the electrode potential have been measured at the interface between n-germanium and 0.1 M Na₂SO₄ + (10^?8 to 10^?6) M Au³⁺ by a complex method. The lattice planes (111), (110), and (100) of germanium were examined. It has been shown that the parameters of states implanted during gold deposition depend on the surface orientation. A correlation has been discovered between the ratio of the hole-entrapment section to the electron-entrapment section and the electrode potential of plane-energy bands. This relation indicates that the parameters of recombination centers depend on the potential distribution across the electric double layer. The study was also concerned with the kinetics of recombination centers generated during gold deposition. It is suggested that the surface states at germanium surfaces in contact with a neutral electrolyte are of the same nature, whether or not such surfaces have been doped with gold.     

Trapping and release of citrate-capped gold nanoparticles

An electrical method to trap and release charged gold nanoparticles onto and from the surface of gold electrodes modified by an alkanethiol self-assembled monolayer (SAM) is presented. To form electrodes coated with gold nanoparticles (GNPs), amine-terminated SAMs on gold electrodes were immersed in a solution of negatively charged citrate-capped GNPs. Accumulation of GNPs on the electrode surface was monitored by a decrease in the impedance of the SAM-modified electrode and by an increase in the electrochemical activity at the electrode as shown through cyclic voltammetry (CV). Electrostatic interactions between the GNPs and the amine-terminated SAM trap the GNPs on the electrode surface. Application of a subsequent negative bias to the electrode initiated a partial release of the GNPs from the electrode surface. Impedance spectroscopy, cyclic voltammetry, ultraviolet-visible (UV-Vis) spectroscopy and atomic force microscopy (AFM) were used to monitor and confirm the attraction of GNPs to and release from the aminealkanethiolated gold electrodes. This work describes a method of trapping and release for citrate-capped GNPs that could be used for on-demand nanoparticle delivery applications such as in assessing and modeling nanoparticle toxicology, as well as for monitoring the functionalization of gold nanoparticles.