Electromagnetics of nanocarbon structures

A great progress has been achieved during last two decade in the synthesis and fabrication of different nanostructured artificial materials with fascinating mechanical, electronic and optical properties irreducible to properties of bulk media. Accompanied by the impressive parallel development of the characterization techniques and measurement instrumentation, this process necessitates the revision of traditional concepts of physics and chemistry of condensed matter, adapting them to peculiarities of the nanoworld and significantly extending our knowledge of the nature of solids and our capabilities to control their properties. Following this general trend, a research discipline - nanoelectromagnetics - is introduced as a synthesis of macroscopic electrodynamics and microscopic theory of electronic properties of different nanostructures. The approach is exemplified by carbon nanotubes (CNTs) and briefly touches upon other nanocarbon forms. Electromagnetic scattering theory is applied to calculate polarizabilities of finite-length single- and multi-walled carbon nanotubes (SW- and MWCNTs) in terahertz and IR ranges. Antenna properties of CNTs and CNT bundles are described. We demonstrate theoretically the dominant role of finite size effect in the non-Drude conductivity of CNT films due to the strong slowing down of surface polariton in CNT. The experimental evidence of the CNT length dependence of the THz spectra of SWCNT films is presented. Thus, experimental results demonstrate the phenomena of localized plasmon resonance in SWCNTs and prove theoretically predicted antenna effect in SWCNTs in terahertz and far-infrared ranges. Significant screening effect is demonstrated to be inherent to electromagnetic response of MWCNTs films at gigahertz frequencies while it practically disappears in the THz range. The main features of the gigahertz and terahertz spectra of effective permittivity and electromagnetic interference shielding efficiencies of a MWCNT-based composite observed previously in experiments are systematized. We demonstrate that surface plasmon-polariton waves with low phase velocity in carbon nanostructures can be utilized for the generation of coherent terahertz radiation through the Cerenkov mechanism, the effect being especially pronounced in spatially expanded double- and and multilayer graphene structures. We describe theoretically and demonstrate experimentally the anomalous absorption of microwave and THz radiation in graphene multi-layered structures and pyrolytic graphite thin films with the tens of nanometers thicknesses (much less than the skip depth). Theory predicts that higher absorption can be achieved with a suitable choice of the dielectric permittivity and the thickness of the substrate. (author)