Melting of Size Selected Clusters and Nanocrystals

Northwestern University, Evanston IL

Investigators

Abstract

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.