As electron microscopists, we are interested in probing the dynamics of physical and chemical processes of functional materials at the molecular and atomic scales in an atom by atom fashion. With fundamental understanding of material behavior at discrete structural features such as defects and interfaces, we can harvest unique properties outside of equilibrium conditions and engineer better materials for energy harvesting and conversion.

Visualizing heat as atomic vibrations in 2D moirés

We use electron ptychography to directly observe thermal vibrations of individual atoms within 2D moiré structures. These measurement enable quantitative measurements of atomic displacements, providing direct insight into phonon behavior and their role in emergent properties of low-dimensional quantum systems.

Tracking of individual atomic displacement during moiré transformation

Using in situ atomic-resolution imaging, we monitor the displacement of individual atoms throughout moiré transformations. This approach enables direct visualization of atomic rearrangement under dynamic conditions, providing insight into how local distortions evolve and stabilize within 2D heterostructures.

Step edge induced phonon softening in MoS₂

We use ultrafast electron microscopy to capture the dynamics of coherent acoustic phonons in heterogeneous materials. The real-space imaging capability enables direct observation of lattice vibration at single picosecond timescales, allowing us to resolve phonon softening induced by a single structural defect. These measurements provide atomic insight into how localized imperfections modulate collective excitations and influence the mechanicla and electronic response of complex materials.