Preparation of Gold Cluster Crystals and Their Electronic State

本研究的主要目的是：1)制备尺寸为1 ~ 3nm的金纳米粒子，该纳米粒子处于量子尺寸范围内；2)使其结晶，实现宏观量子尺寸效应，并阐明其磁性能。通过我们的技术，可以调节单个纳米颗粒的核心尺寸，绝缘体的厚度，屏障的高度，取代残基之间的相互作用。因此，这一新的方法有可能制备出一种不同于传统沉积技术的新型超结构。我们可以预期，在比纳米粒子小得多的簇状分子中，会出现一个诸如幻数之类的特征。通过这个项目，我们也期望在这些团簇材料中获得详细的固态特性。我们用蒸汽扩散法制备了巯基琥珀酸修饰银粒子的高质量颗粒晶体作为实验材料，证明了该方法的有效性。即使从40%粒度宽度的宽粒度分布开始，我们也成功地制备了良好的无粒度分离的颗粒晶体。我们现在正计划将这种方法应用于获得金纳米颗粒晶体。我们已经开始测量金纳米颗粒沉积膜的输运特性，以表征其从室温到20k的电子特性。沉积膜的电导率表现出特有的温度依赖性，具有较小的温度系数的金属性质。我们还发现，同样的薄膜能够测量光学吸收实验，这意味着，即使薄膜的厚度，这种薄膜是透明的。一项更全面的实验正在进行中。用乙酰基GTR配体获得了具有五边形对称的粒子晶体。晶体的大小在微米量级。这是一种独特的物质在一组超晶格的纳米颗粒。我们项目的下一个目标是使更多的小颗粒在具有尖锐尺寸分布的簇态中结晶，就像它是分子材料一样。为了实现这一目标，我们正在开发一种新技术，该技术使用不到一毫克的样品粉末来获得晶体并在毛细管内结晶。少

The main object of this research is 1) To prepare gold nanoparticles in the size range from 1 to 3 nm, which is in the quantum size regime,2) To crystallize these nanoparticles to realize macroscopically quantum size effect and to clarify its magnetic properties. With our technique, it is possible to regulate the core size of a single nanoparticle, the thickness of insulator barrier height, interaction among substituted residues. Hence it is possible to prepare a new type superstructures different from those manufactured by conventional deposition techniques because of a new approach. We can expect a characteristic feature such as a magic number in cluster molecules whose sizes are much smaller than a nanoparticle.. Through this project, we also expect to get detailed solid state properties in these cluster materials.We have applied a vapor diffusion method to prepare a quality particle crystal of mercaptosuccinic acid modified silver particles as an test material to demonstrate the ef … More fectiveness of this method. Even starting wide size distribution with 40% size width, we have succeeded in preparing a good particle crystal without size separation. We are now planning to apply this method to get a gold nanoparticle crystal. We have started measurement of transport properties of deposited film of gold nanoparticle to characterize its electronic properties from room temperature down to 20 K. The deposited film revealed characteristic temperature dependence in the conductivity showing the metallic character with slightly small temperature coefficient. We have also found that the same film was capable to measure optical absorption experiment that means this film is somewhat transparent even though the thickness of the film. A more comprehensive experiment is now under going.A particle crystal that has pentagonal symmetry was obtained with acetyl GTR ligand. The crystal size is in the order of micron meter. This is a unique substance in a group of superlattice of nanoparticles. The next target of our project is to crystallize more small particles in the regime of cluster with a sharp size distribution as if it were molecular materials. To realize this object, we are now developing a new technique which uses less than a milligram sample powders to get crystal and crystallize within a capillary. Less