银胶体系中吖啶橙、吡啶共吸附竞争的研究

本文利用光学多道分析仪,着重研究了吖啶橙—银胶—吡啶体系;观察了吖啶橙荧光的两次瞬间增强的时间效应荧光谱;分析了吖啶橙与吡啶在银表面上共吸附竞争以及氯化钾在这一竞争中所起的作用。对于表面与分子间相互作用的这一规律作了初步探讨。     

染料分子荧光淬灭规律研究

本文研究了若丹明B、若丹明6G和吖啶橙三种染料分子吸附于银表面上时的荧光变化规律,发现在银胶颗粒表面的吸附均造成了其荧光强度急剧而大幅度的淬灭,淬灭随时间呈双曲线型衰减。同时利用这一实验结果对分子在表面间的吸附系数与脱附系数——这些表征分子与表面相互作用的重要参数——表达式进行了初步推导。     

染料分子荧光淬灭规律研究

本文研究了若丹明B、若丹明6G和吖啶橙三种染料分子吸附于银表面上时的荧光变化规律,发现在银胶颗粒表面的吸附均造成了其荧光强度急剧而大幅度的淬灭,淬灭随时间呈双曲线型衰减。同时利用这一实验结果对分子在表面间的吸附系数与脱附系数——这些表征分子与表面相互作用的重要参数——表达式进行了初步推导。     

苯甲酸和对羟基苯甲酸与Cl~-在银表面上吸附竞争的SERS研究

对Cl~-在银胶体系中与苯甲酸(C_6H,COOH)和对羟基苯甲酸(HOC_6H_4COOH)在银表面上的相互作用和吸附竞争进行了研究,证实了Cl~-对上述两类分子的SERS信号增强具有明显的淬灭效应.1640cm~(-1)振动所反映的Cl~-存在前后—COO~-与银表面相互作用强弱的变化,证实了Cl~-促使分子从银表面脱附这一过程的存在.同时对—OH在其中的影响作了讨论.     

表面增强喇曼散射(SERS)光谱中影响增强效应因素的实验研究

本文研究了银电极表面的电化学预处理、电极的外加电位和放在卤化物溶液中的银电极在电化学预处理过程中的激光辐照对喇曼光谱表面增强效应的影响。实验结果表明,银电极的电化学预处理有利于吡啶分子的吸附;银电极的外加电位和激光辐照使得吡啶分子吸附于粗糙银电极表面。最后,定性地讨论了电化学预处理,外加电位和激光辐照影响喇曼光谱表面增强效应的实验结果。     

银电极上2-巯基吡啶和4-巯基吡啶自组装单层的原位表面增强拉曼光谱电化学

利用原位表面增强拉曼散射(SERS)技术,分别观察了2-巯基吡啶和4-巯基吡啶在银表面自组装单层的电化学行为。实验结果表明,随着电位的负移,2-巯基吡啶和4-巯基吡啶分子在银表面均呈现出先倾斜再垂直然后倾斜的吸附取向改变过程。但发生完全脱附的电位则有所不同。     

银溶胶吸附的维酶素的表面增强共振拉曼散射

获得了银溶胶吸附的维酶素的表面增强共振拉曼散射光谱(SERRS)。维酶素的水溶液加到银胶中形成银胶—维酶素络合物,可使吸收谱带在440—650nm范围出现。维酶素的组分与银溶胶发生了竞争结合,而维酶素的FAD在竞争中占优势,故吸附在银溶胶表面的维酶素的SERRS实际上是FAD的异咯嗪和腺嘌呤二核苷酸的振动光谱。在维酶素中FAD作为辅基与蛋白质相连,它与蛋白质相互作用使其拉曼谱线发生3—8cm~(-1)位移。因此SERRS技术对带发色团的蛋白质结构的研究很有用处。     

表面增强Raman效应(SERS)

一、表面增强拉曼效应(SERS)及特点1974年Fleischman等进行了首次电化学池中银电极表面上吸附的吡啶分子的Raman散射实验。为了增加散射强度,他们把电极进行数次氧化还原处理,增大表面积,吸附更多的分子。经处理后他们果然得到了散射信号,并发表了文章。可是另外一些科学家不相信这是真的,因为按他们的估算吸附的分子只有一到几层,散射信号是弱到不可能测出来的。他们更仔细地重复了Fleischmall等人的实验,出乎意料地,他们也测到了信号。经过认真核对并与不吸附在银表面上的吡啶散射强度相比,他们宣布:吸附在银电极表面上的吡啶分子的散射截面比普通     

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     

KCI对银胶形态影响的电子显微镜研究

借助透射电子显微镜研究了银胶中加入KCl时对银胶的影响。发现KCl的加入引起了银原子的输运,使胶体颗粒变大,表面上覆上一层疏松原子集团。同时引起胶体发生链状凝聚。和加入吡啶引起的银胶的变化做了比较,表明KCl和吡啶对银胶的作用结果有很大差异。同时也讨论了这些差异对表面增强喇曼散射信号的影响。 关键词：     

Carbon monoxide and hydrogen coadsorption on polycrystalline platinum

The coadsorption of carbon monoxide and hydrogen was studied on a polycrystalline platinum foil. In a comparison with single crystal surfaces, the desorption kinetics of the individual species most closely resemble those on Pt(110). In coadsorption there is competition between CO and H₂. Carbon monoxide completely blocks hydrogen adsorption, but on a hydrogen-saturated surface only two-thirds of the carbon nomoxide adsorption is blocked. Shifts in peak temperatures for hydrogen desorption indicate that repulsive interactions between adsorbed CO and H₂ are important, and lead to segregated islands of the two adsorbates. Under some conditions there is also a new low temperature desorption peak for hydrogen which indicates that there are regions on the surface where carbon monoxide and hydrogen are intermixed.     

Rare gas coadsorption with Cs or K on Ag(111)

Rare gas (RG) coadsorption with submonolayer amounts of Cs or K on Ag(111) was studied using low-energy electron diffraction (LEED). A crossover in the alkali-RG interaction from repulsive to attractive was observed as a function of alkali species and of alkali coverage. The K---RG interaction was observed to be repulsive at all coverages, while the Cs---RG interaction was observed to be attractive at low Cs coverages and apparently repulsive at high Cs coverages. For the K + RG adsorption system, desorption data were analyzed to determine the spreading pressure in the alkali layer, thus showing that RG can be used as a 2D manometer in some coadsorption systems. From the spreading pressure it is possible to obtain some information about the properties of the adsorbed alkali such as the energy differences between commensurate and incommensurate phases. We also demonstrate that work function measurements from such coadsorption systems do not necessarily have a simple interpretation.     

Cu(111)面K-O复合物的形成

本工作对室温Cu(111)面CO,O₂和K的共吸附进行研究。高分辨电子能量损失谱(HREELS)的实验结果表明:由于K的出现,室温下Cu表面上可以有分子状态的CO存在。C0与K在Cu(111)面上共吸附时,CO分子中的O可以和K形成“K-O”复合物,“K-O”复合物的形成与K在Cu表面上的状态有关。只有在K覆盖度大于0.04时,K原子出现退极化时。“K-O”复合物才被观察到。 关键词：     

CO and O coadsorption on Pt3Sn studied by DFT: Changes in the adsorptive properties of the surface with alloying and coverage

Adsorption of CO and coadsorption of O and CO on Pt₃Sn(1 1 1) was studied using periodic DFT calculations. Calculations were performed on Pt(1 1 1) by using the same set of parameters and their results were used as reference basis. The calculations showed that the most stable configuration with the minimum energy for coadsorption of CO and O is CO adsorbed atop Pt and O adsorbed on fcc Pt2Sn hollow site and that the decrease in the adsorption strength of the system at a total surface coverage of 0.5 ML is by 0.063 eV as a result of coadsorption, with respect to the adsorption of one species individually. Results show that the interaction between the adsorbed CO and O is short range on PtSn alloy, contrary to that on pure Pt, and this is mainly related to stronger Sn–O bonds compared to Pt–O bonds which eventually reduce the surface strain at the coadsorption structure. There is a pronounced effect of total surface concentration on the adsorption energy of coadsorbed species; the adsorption strength is not directly proportional to the surface coverage but is also related to the distribution of the coadsorbed species on the surface.     

时间分辨表面增强拉曼光谱研究银电极表面硫脲和ClO_4~-共吸附层的结构

本文应用时间分辨表面增强拉曼光谱（ＴＲＳＥＲＳ）结合电位阶跃和电位扫描的方法，研究了硫脲和ＣｌＯ－４在Ａｇ电极表面的共吸附层结构。结果表明ＳＥＲＳ谱峰强度随电极电位的响应速率与电位阶跃扫描的方向有关，ＴＵ和ＣｌＯ－４在Ａｇ表面的共吸附层在不同的电位下存在两种不同的构型，并且两种构型之间转化的难易程度不同。     

Thermal desorption of N2 from (N2 + O2) coadsorbed on polycrystalline rhenium surfaces

The coadsorption of ¹⁵N₂ and O₂ on polycrystalline rhenium filament has been studied by thermal desorption mass spectroscopy. The sample was exposed to a mixture of ¹⁵N₂ and O₂ with various concentrations of ¹⁵N₂ at room temperature. It is suggested that NO on Re at low coverage is dissociative and the bonding strength of nitrogen on Re is weakened by the coadsorption with oxygen atoms.     

Reactions of small gold cluster cations with propylene, methane, and hydrogen: permissive and competitive coadsorption effects

Coadsorption effects of molecular hydrogen and small hydrocarbons, CH₄ and C₃H₆, on free Au₃ ⁺ and Au₅ ⁺ were investigated in an octopole ion trap under multi-collision conditions. For hydrogen and methane the observations indicate that both molecules coadsorb on the same adsorption site, i.e., the same atom of the cluster. This type of molecular adsorption on free clusters is termed permissive coadsorption, in contrast to competitive coadsorption, in which two molecules compete for the same adsorption site. The latter case was observed for hydrogen and propylene: already trace amounts of propylene were able to completely saturate the clusters preventing the coadsorption of H₂. The size dependent adsorbate coverage is discussed and implications on the cluster structure are deduced from time and temperature dependent reaction measurements.