PNNL

Abstract

Nucleation is the seminal process in formation of ordered structures ranging from simple inorganic crystals to macromolecular matrices. Observations over the past fifteen years have revealed a rich set of hierarchical nucleation pathways involving higher-order species ranging from multi-ion clusters to dense liquid droplets, as well as transient crystalline or amorphous phases. Despite this complexity, a holistic framework for understanding hierarchical pathways that is rooted in classical concepts emerges when the coupled effects of perturbations in free energy landscapes and the impact of dynamical factors are considered. Here I describe that framework and use a series of in situ TEM and AFM studies on inorganic, organic, and macromolecular systems to illustrate the evolution in nucleation processes as these perturbations and dynamical factors come into play. The results provide a common basis for understanding development of order in systems as diverse as simple salt crystals, branched semiconductor nanowires, and microbial membranes.