Electromagnetic Resonances of Individual Single-Walled Carbon Nanotubes With Realistic Shapes: A Characteristic Modes Approach

In composites, carbon nanotubes (CNTs) are rarely perfectly straight and they usually exhibit complex shapes. In this paper, we employ the method-of-moments formulation for arbitrary thin wires to study the electromagnetic scattering characteristics of CNTs with realistic shapes. More than 800 different CNT shapes were simulated in this work. These shapes were generated using a coarse-grained molecular dynamics model calibrated using realistic CNT shapes encountered experimentally. The analysis shows that the shape and orientation of CNTs has a strong effect on the scattered electromagnetic response. We used the theory of characteristic modes (TCM) to explain this dependence of the scattered electromagnetic waves on the shape of the CNT. Using TCM, we developed simplified but highly accurate formulas that link the shapes of the CNTs to the resonances in their total extinction coefficient spectrum. These formulations have the potential to be the basis for advancing the nondestructive evaluation of CNT composites using electromagnetic waves as well as the development of novel CNT electromagnetic systems and devices.