Study on the monolayer arrangement and optical properties of single-dispersed metallic particles on solid surfaces

固体表面单分散金属粒子的单层排列及光学性质研究

基本信息

批准号：
15560570
负责人：
HATTA Aritada
金额：
$ 1.98万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

项目摘要

1.Infrared absorption spectral measurements have been performed at normal incidence of radiation on octadecanethiol (ODT) deposited from ethanol-water mixed solutions onto colloidal silver particles (ca. 30 nm in diameter) on Si(111) substrates. The spectra taken as a function of silver mass thickness and ODT concentration. indicate that the absorption bands of ODT are enhanced in intensity in comparison to the case in which no silver particles are present. It is also found that regardless of ODT concentration each absorption band reaches a maximum in intensity at a particular mass thickness of the particles, suggesting an intimate relationship between the absorption enhancement and the aggregation of the particles. This indeed was supported by FE-SEM morphological inspection of the particles.2.Aggregation of silver colloidal particles in the hydrosol through chemisorption of ODT molecules has been investigated on the basis of UV-visible transmission and infrared attenuated total refle … More ction (ATR) experiments. As-prepared silver sol showed a single absorption peak centered at 395 nm due to plasma resonance of the particles. Upon addition of ODT-dissolved ethanol to the sol, the plasma resonance peak showed a redshift accompanying a broadening, an indication of the aggregation of the particles in the solution by ODT adsorption. By use of infrared ATR spectroscopy, it was found that the particles in the solution aggregate on the base plane of a germanium ATR prism upon addition of ODT-dissolved ethanol to the solution. At moderate ODT concentrations, intense aggregation via ODT adsorption takes place on the prism surface, thus making it possible to observe ODT absorption bands.3.Raman scattering from the adsorbed species on the colloidal particles after dropping on Si substrates has been taken using a He-Ne laser (632.8 nm) in order to more clarify the influence of ionic species produced during preparation of the colloidal silver sol upon aggregation of the particles after dropping the particles on the silicon substrate. A Raman band due to nitrate ion was observed. This band almost disappeared by immersing the deposited silicon substrate into pure water far 1 hour. However ; the nitrate band was observed more strongly after immersion of the substrate into the water for 5 hours. This increase of Raman scattering intensity can be explained by assuming that the environmental nitrate ions were diluted or adsorbed nitrate ions were desorbed more or less by the water and thereby aggregation of the silver colloid particles proceeded, leading to an increase of the so-called SERS active sites. Actually, no Raman bands due to ODT could be observed when the deposited silicon substrate was subsequently immersed into ODT-dissolved ethanol This maybe explained by assuming that the SERS active sites were occupied by nitrate ions. Less

1.在垂直入射的辐射下，对从乙醇-水混合溶液沉积到 Si(111) 基底上的胶体银颗粒（直径约 30 nm）上的十八烷硫醇 (ODT) 进行红外吸收光谱测量。银质量厚度和ODT浓度的函数表明，与不存在银颗粒的情况相比，ODT的吸收带强度增强。每个吸收带在颗粒的特定质量厚度处达到最大强度，这表明吸收增强与颗粒聚集之间存在密切关系，这确实得到了颗粒的FE-SEM形态检查的支持。2.聚集。基于紫外-可见光透射和红外衰减全反射 (ATR) 实验，研究了通过 ODT 分子的化学吸附在水溶胶中形成银胶体颗粒。由于颗粒的等离子共振，溶胶显示出以 395 nm 为中心的单一吸收峰。将 ODT 溶解的乙醇添加到溶胶中后，等离子共振峰显示出红移并伴随着变宽，这表明颗粒在溶胶中聚集。通过红外ATR光谱法发现，当向溶液中加入ODT溶解的乙醇时，溶液中的颗粒聚集在锗ATR棱镜的基面上。在中等ODT浓度下，ODT吸附在棱镜表面上发生强烈聚集，从而可以观察到ODT吸收带。3. 拍摄了滴在硅基板上后胶体颗粒上吸附物质的拉曼散射。使用氦氖激光（632.8 nm），以更清楚地阐明胶体银溶胶制备过程中产生的离子种类对将颗粒滴在硅上后颗粒聚集的影响将沉积的硅基板浸入纯水中1小时后，观察到由硝酸根离子产生的拉曼带，然而，在将基板浸入水中5小时后，观察到更多的硝酸根带。拉曼散射强度的增加可以通过假设环境硝酸根离子被稀释或吸附的硝酸根离子或多或少被水解吸从而银聚集来解释。胶体颗粒继续发生，导致所谓的 SERS 活性位点增加。实际上，当沉积的硅基板随后浸入 ODT 溶解的乙醇中时，没有观察到由 ODT 引起的拉曼带。这可以通过假设 SERS 活性来解释。硝酸根离子占据的位点较少。