physics_175_2

Physics Colloquium - February 21, 2013

Thermo-induced transformations in carbon based materials: MD viewpoints

Abstract: This talk illustrates several applications of molecular dynamic simulations. These examples show MD can predict a new class of devices and provide insights for materials management at the nanoscale. First, we create and understand basic properties of a nanoelectromechanical mass-sensor based on the single graphene membrane. By exposing graphene mat to a different types and amounts of molecules within a classical MD interface, we prove that this “nanoscale ear drum” may act not only as a mass variation sensor but also as an effective information transmitter with respect to graphene-molecule interactions. We read out this information through dynamical response functions imprinted in a tunneling current. Next, we build graphene based structures in a catalyst-free fashion directly from amorphous carbon (a–C). Theoretically, using a MD driver at DFTB(density functional tight bonding) level of theory we will mimic a substrate Joule heating d induced by current through device. We will show how, under heating. a-C dust can be transformed into well-organized graphene patches and to be self-healed. Finally, we will discuss a constructive and distractive nature of knock-on damage within a high resolution transmission microscopy experimental set-up. Here again, MD based theoretical experiments help us to provide an explanation of how one can use deposited amorphous carbon to engineer graphene (making holes etc.) either for its catalyst-free fabrication or its destruction.

Stanislav Avdoshenko
School of Materials Engineering
Purdue University
Stanislav Avdoshenko