Melting and Freezing: From Clusters to Nanoparticles

在这个由化学系实验物理化学项目资助的奖项中，印第安纳大学的马丁·F·雅罗尔德教授、他的博士后研究员和研究生将进一步研究1000个金属原子的孤立团簇的熔化和冻结行为。这些实验是通过测量一束大小选定的金属团簇离子通过高压碰撞池时的衰减来进行的。一些将被研究的行为包括：随着团簇尺寸的增加，从动态相共存到静态相共存的转变，表面预熔的性质，冻结的动力学，杂质原子的影响，以及液体团簇的性质。该小组将与印度浦那的Kanhere理论小组合作，在那里将进行团簇熔化的分子动力学模拟。人们对纳米尺寸金属颗粒熔化的本质知之甚少。贾罗尔德教授的实验为我们提供了关于这些不寻常的、技术上重要的材料的重要物理性质的新信息。除了这项研究的更广泛的科学影响外，这项工作还为从本科生到博士后水平的年轻科学家提供培训。

In this award, funded by the Experimental Physical Chemistry program of the Chemistry Division, Professor Martin F. Jarrold of Indiana University, his post-doctoral fellow and graduate students will further their work studying the melting and freezing behavior of isolated clusters of 1000 metal atoms. These experiments are conducted by measuring the attenuation of a beam of size-selected metal cluster ions as they pass through a high pressure collision cell. Some of the behaviors that will be studied include: the transition from dynamic to static phase coexistence as cluster size increases, the nature of surface pre-melting, the kinetics of freezing, the effects of impurity atoms, and the nature of liquid clusters. The group will collaborate with the theoretical group of Kanhere in Pune, India, where molecular dynamics simulations of cluster melting will be carried out.The nature of the melting of nanoscopic sized metal particles is poorly understood. Prof. Jarrold's experiments are providing us with new information on this important physical property of these unusual, technologically important materials. Besides the broader scientific impact of the research, the work provides training to young scientists from the undergraduate through the postdoctoral level.