MATERIALS RESEARCH SCIENCE AND ENGINEERING CENTER
IRG 2: Molecular Crystal Growth Mechanism
Senior Investigators and Research Projects
solid state chemistry,
Theory guides subsequent experiments
Structure and energy underpin all aspects of crystal growth. Despite substantial effort and some progress during the past two decades, predicting molecular crystal structure remains a challenge. The aim of this project is to create new tools for cutting through free energy landscapes in order to identify and rank crystalline polymorphs.
J. Bernstein (NYU Global Professor)
N. Marom (Tulane)
L. Kronik (Weizmann)
A. Rohl (Curtin U., Australia)
L. Yu (U. Wisconsin, Madison)
Y. Zhang (NYU Chem)
Sequence of relative rates of unit cell assembly
The growth of a crystal can be viewed as a complex reaction mechanism not substantially different from a chemical reaction mechanism: a sequence of structurally well-defined steps whose relative rates are assigned. Crucial to labeling steps in the crystal growth process are assays of the locations of additives that can serve to discriminate symmetry related facets that are dissymmetric on a growing surface.
J. Chmielewski (Purdue)
K. Kirshenbaum (NYU Chem.)
J. M. McBride (Yale)
Elastic and plastic distortions in growing crystals and polycrystal pattern formation
Additive are essential not only in revealing stepwise mechanisms at the unit cell level, they determine the macroscopic consequences of a crystallization process, the morphology of single crystals. A great variety of recently discovered additive-induced distortions of crystals depend critically on supramolecular selectivity and on the poorly understood elasticity and plasticity of molecular crystals to be analyzed here.
D. Hooks (LANL)
P. Naumov (NYU Abu Dhabi)
K. V. Stojanoff (Brookhaven)
Induced nucleation with structured light and in confinment
Advances in the science of crystal nucleation rely on the generation of nuclei with spatiotemporal control. IRG 2 researchers will minimize the stochastic nature of crystal nucleation with light fields and with tailor-made crystallization containers. Light will be used to sieve nuclei of different polymorphs that form concomitantly, obviating the need for control in practical cases where the kinetics of nucleation and growth of distinct polymorphs are closely matched.
S. Arnold (NYU.POLY Appl. Phys.)
Origin and structure of growth active dislocations
The study of the kinetics of growth spiral propagation has advanced spectacularly with the rise of realtime in situ AFM. This work has animated the growth of hillocks that arise from emergent screw dislocations, and provided kinetic data that can be reduced to activation parameters associated with step advancement across crystal faces. Unfortunately, these studies do not reveal the origin of growth spirals or their core structures, critical aspects of molecular crystal growth mechanisms. Moreover, understanding dislocation formation is a first step in controlling their formation. Defect free molecular crystals are critical to performance, particularly in applications involving charge transport.