Symposium FF03: Building Advanced Materials via Particle-Based Crystallization and Self-Assembly of Molecules with Aggregation-Induced Emission
Qian Chen, University of Illinois at Urbana-Champaign
Direct Imaging of Layer-by-Layer Growth in a Colloidal Nanoparticle Superlattice
Written by Alana F. Ogata
Who doesn’t love a good movie? Qian Chen’s talk was filled with movies at the nanoscale as she presented recent in situ transmission electron microscopy (TEM) studies of nanoparticle superlattices. In situ TEM circumvents the limitations of vacuum-conditions in traditional TEM and enables direct imaging in a liquid cell. Chen utilizes low dose in situ TEM to study the crystallization of nanoparticles during the formation of superlattices. The audience next watches a video of cubic nanocrystals accumulating layer-by-layer at the crystal surface revealing the growing morphology of a superlattice. Beyond watching movies, molecular dynamic simulations reveal a 2-step nucleation mechanism comprised of an amorphous precursor nucleation domain and crystal nucleation within the amorphous precursor. In situ TEM movies are captivating but typically suffer from criticisms that come from electron beam radiation damage and challenges controlling the local environment. Careful optimization of in situ TEM studies presented in this talk, Chen points out, was extensive and detailed in a 75-page supplementary document.