Noncontact Atomic Force Microscopy - Yale School of Engineering ...

Mo-1140
Van der Waals with a twist: how nanotube chirality impacts interaction
Rick F. Rajter 1
strength.
1Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge,
MA, USA
The van der Waals - London dispersion interaction depends on the geometries and optical
properties of all materials or components present within a given system. The ongoing
investigation of the material property contribution to this interaction continues to yield
novel and sometimes surprising phenomenon. A chronological review of these
developments helps underline the importance of material property thinking and why these
effects must be considered. When first discovered, the differences in interaction strength
were largely attributed to variations in atomic composition, such as that between various
noble gases. Once Lifshitz quantified the connection of interaction strength to the
system’s optical properties, differences in said interactions were also predicted and
confirmed for allotropes. Perhaps the most obvious example is that of carbon, which can
take the form of diamond, graphite, graphene, nanotubes, buckyballs, ribbons, etc. Here,
it was the bond type that was the differentiating factor. The most recent discovery was
that bond twisting or bending within a given allotrope (i.e. carbon nanotubes) could lead
to equally dramatic changes. One of the unique features of carbon nanotubes is that a
very small change in the chirality or twist can greatly change the electronic structure
properties, which are the key determining factor a material's optical properties. This
work will show many examples of chirality-dependent optical properties and how this
information can be used to create experiments to exploit these differences for a variety of
applications.
34