Reactivity and Dynamics of Gaseous Clusters. The Dynamics and Controlled ShapedSynthesis of Gaseous and Colloidal Nanoparticles

摘要

In order to design new strategic materials with specific properties, we need tounderstand the binding forces that exist in mixed atoms or molecules not present in conventional material. Thus our aim is to understand the adhesive and cohesive forces holding atoms or molecules together in unconventional nanoparticles that do not usually bind together in conventional macroscopic materials. In the broad sense, we like to understand these forces by studying the structure, stability, and the dynamic process of the rapid electronic motion in nanoparticles. Due to the large surface to volume ratio, these particles tend to have different properties not present in the bulk nor of the individual atoms or molecules making these nanoparticles. Thus they offer us an opportunity to unravel new properties with new potential applications. The aim of our present research is to synthesize and study the forces between atoms or molecules within metallic and semiconductor nanoclusters. These forces determine the dynamic properties and thus the potential uses of the nanoparticles. In the past several years, we have confined our studies to gaseous clusters and studied the dynamics of their dissociation and their chemical reactivities. During the past couple of years (since we have moved to Georgia Tech), we have expanded our activity to include the synthesis and study of the dynamics of excitation relaxation in colloidal nano-particles, both semiconductor and metallic. The forces that control the shapes of nanoclusters by capping agents are to be examined. The synthetic method we use involves a competition between nucleation of the atoms in the metallic nanoparticles or the semiconductor molecules in the semiconductor nanoparticle and the capping process of the surface with polymeric molecules. The faster the capping process, the smaller would be the average size of the clusters formed.