ST colloquium Prof. dr. Jim De Yoreo

03 mei
12:45 - 13:45
Helix STC 001

Titel: They Call it “Free Energy” So, Hey, Why Pay?

Nucleation is the seminal process in the formation of ordered structures ranging from simple inorganic crystals to macromolecular
films. Recent observations have revealed a rich set of hierarchical pathways involving higher-order species ranging from multi-ion
clusters to dense liquid droplets to transient amorphous or crystalline phases. Despite their complexity, a holistic framework for
understanding such pathways based on classical concepts emerges when the effects of complexities in free energy landscapes and
kinetic factors are considered. I illustrate that framework using in situ TEM and AFM studies of inorganic, organic, and
macromolecular systems. The results show that introduction of size-dependent phase stability or high driving force coupled with
the existence of metastable polymorphs leads to true two-step pathways characterized by the initial appearance of a bulk precursor.
Creation of micro-states representing local free energy minima stabilized by configurational factors also drives hierarchical
pathways, but the intermediates can only exist as transient microscopic entities. Small changes in molecular structure can
eliminate these transients and lead to direct nucleation pathways. In either case, reduction in molecular mobility can freeze in nonequilibrium
states for kinetic reasons. The findings provide a common basis for understanding the development of order in diverse

Jim De Yoreo is Chief Scientist for Materials Science at Pacific Northwest National Laboratory (PNNL) and Affiliate Professor of Materials
Science and Engineering at the University of Washington. He received his PhD in Physics from Cornell University in 1985. Following postdoctoral
work at Princeton, he became a member of the technical staff at Lawrence Livermore National Laboratory in 1989, where he held
numerous positions including Deputy Director of the Laboratory Science and Technology Office. He joined Lawrence Berkeley National
Laboratory in 2007 where he was Interim Director of the Molecular Foundry before moving to PNNL in 2012. De Yoreo’s research spans a
wide range of materials-related disciplines, focusing most recently on interactions, assembly, and crystallization in inorganic, biomolecular and
biomineral systems. De Yoreo has authored, co-authored, or edited over 225 publications and patents. He is a recipient of the David Turnbull
Lectureship of the Materials Research Society (MRS), the Laudise Prize of the International Organization for Crystal Growth’s (IOCG), the
Crystal Growth Award of the American Association for Crystal Growth (AACG), and an R&D 100 Award. He is a Fellow of the American
Physical Society and the MRS, a member of the IOCG Executive Committee, and served as MRS President.