Formation of Nanoparticle Ensemble and its Electronic Structure : From Fractal Cluster to Particle Crystal

在预定的时间内，我们开发了一种能够使用高密度纳米胶体在石英或HOPG衬底上浇铸薄膜的制备技术，并利用本实验室引入的STM/AFM观察了它们的结构。在过去的一年里，我们的工作集中在金纳米颗粒薄膜的形成和孤立颗粒尺寸的确定上，除了以前的物理过程制备方法外，我们还尝试了一种新的胶体化学方法。结果表明，用硫代巴比妥作尺寸控制剂时，制得的颗粒尺寸最小，为1um。采用有机还原法制备了粒径大于10 nm的纳米粒子，其粒度分布宽度较窄，为15%。用各种物理化学方法测定了这种硫代修饰粒子的精确表面状态。为了达到颗粒结晶的目的，我们利用硫醇表面修饰的方法进行了g量级的大规模合成。这一数量与物理干燥过程中的镁含量相差甚远。在实验的最后阶段，测试了Au-MSA修饰纳米颗粒的晶体形成。考察了水/有机溶剂、一种溶剂(甲醇、乙醇、异丙醇)的含量、盐浓度、一种盐(硫酸铵、氯化铵)、结晶温度等调节参数。使用蛋白质化学领域著名的微板法对数百种不同的条件进行了测试。遗憾的是，大尺寸晶体的形成并不适合X射线分析。未来的研究中仍将保留层析或选择尺寸沉淀法等尺寸分离技术，以形成三维大尺寸晶体。

During a scheduled period, we have developed a preparation technique enables casting film on quartz or HOPG substrate using high density nanocolloids and observed their structure by STM/AFM which is incorporated in our laboratory. In the last year, we have focused our effort on the formation of gold nanoparticle film together with the confirmation of the size of isolated particles.In addition to the previous preparation method using physical process, a new colloid chemical method was also attempted. It was found that a particle with the smallest size of 1um was prepared when using thiolate as a size controller. A particle whose size is larger than 10nm was formed by the organic reduction method and was fount that the size distribution width is narrow as 15%. The precise surface state of this thiolate-modified particles was determined using various physico-chemical method. In order to aim the particle crystal formation, we have developed a large scale amount synthesis in the order of g using thiol surface modified method. This amount is far from that by the physical dry process in the order of mg. In the final stage of the experiment, particle crystal formation was tested using Au-MSA modified nanoparticles. The regulation parameters tested were content of water/organic solvent, a kind of solvent (methanol, ethanol, 2-propanol),salt concentration, a kind of salt (ammonium sulfate, ammonium chloride), and crystallization temperature. More than several hundreds different conditions were tested using a micro-plating method, well-known in the field of protein chemistry. Unfortunately, a large size crystal formation was not perceived appropriate for the X-ray analysis.The size separation technique such as chromatography or the size-selected precipitation method was remained in a future study to form a three dimensional large size crystal.