Melting of Size Selected Clusters and Nanocrystals

在这个由化学系物理化学计划资助的项目中，西北大学的马丁·雅罗尔德将继续进行一项研究计划，以检查材料从宏观尺寸减小到微观尺寸时熔化过程中的变化。离子迁移率技术将用于研究金属团簇离子在气相中的熔化。使用这种方法可以感知熔化时发生的星团的体积或形状变化。有关聚变潜热的信息将通过离子迁移率池中的碰撞诱导解离来确定。将对各种金属和碱卤化物团簇进行测量。随着块体材料的尺寸缩小到纳米级，目前关于熔化材料行为变化的实验数据非常少。这项研究项目将深入了解在非常小的系统(少于500个原子)中整体熔化和类似行为之间的联系，并最终应该有助于解释如何制备纳米尺寸的颗粒。因此，它意味着将纳米级结构的合成从一门艺术变成一门科学，并将影响纳米技术的许多方面。

In this project funded by the Physical Chemistry Program of the Chemistry Division, Martin Jarrold of Northwestern University will pursue a program of research to examine the changes in the melting of a material as it decreases in size from a macroscopic to a microscopic scale. The ion-mobility technique will be used to study the melting of metallic cluster ions in the gas phase. Using this method the volume or shape change of a cluster that occurs upon melting will be sensed. Information about the latent heat of fusion will be determined using collision-induced dissociation in an ion mobility cell. Measurements will be performed for a variety of metal and alkali-halide clusters. Very little experimental data is currently available about the change in the behavior of melting materials as the size of the bulk material shrinks to the nanometer regime. This research project will provide insight into the connection between bulk melting and analogous behavior in very small-size systems (fewer than 500 atoms) and should ultimately help explain how to prepare nanometer-sized particles. As such it has implications for turning the synthesis of nanoscale structures from an art into a science and will affect many aspects of nanotechnology.