"Harnessing Forces and Heat to Study and Pattern Atomic Interfaces"

Elisa Riedo, CUNY

Abstract: The ability to understand and harness forces and heat at the nanoscale opens up a variety of possibilities for investigating the interaction between atomic interfaces, from graphene-graphene Van der Waals interaction to the interaction between a solid surface and a one-molecule-thick film of water. The focus of my laboratory is to study elasticity [1], friction, and viscoelasticity [2] at atomic solid-solid and solid-liquid interfaces by combining forces and heat in innovative atomic force microscopy methods.

In this seminar, I will first present our novel sub-Å-resolution indentation measurements of the perpendicular-to-the-plane inter-layer elasticity of a-few-layers thick graphene and graphene oxide films [1]. Interestingly, we find that the perpendicular Young’s modulus of graphene oxide films reaches a maximum when one complete water layer is intercalated between the graphitic planes. The interlayer Van der Waals elastic coupling is particularly important since it is related to the thermal, electronic, and tribological properties of multi-layer Van der Waals films and nanotubes. Our methodology can map inter-layer coupling and intercalation in Van der Waals films as well as the radial elasticity of nanotubes, which gives rise to large dissipative forces when a nanotube slides on a surface perpendicularly to its axis, but not when it slides along its axis. In the second part of the seminar, I will present our recent results on the extremely large viscoelasticity of molecularly thin water films, and I will discuss the interplay between viscosity, wettability, and slip in interfacial water flow [2]. Finally, I will briefly overview the capabilities of thermo-chemical Scanning Probe Lithography [3], tc-SPL, invented in our laboratory at GT for patterning high performance electrodes on 2D layers, for grey-scale chemical nanopatterning and for spintronics applications.

1. “Elastic coupling between layers in two-dimensional materials” Nature Materials 14 (7), 714-720 (2015)
2. “The interplay between apparent viscosity and wettability in nanoconfined water", Nature Communications, DOI: 10.1038/ncomms3482 (2013).
3. “Advanced Scanning Probe Lithography”, Nature Nanotechnology, 9, 577 (2014)