Charge Transfer Plasmon Resonance in a Dimer Consisting of Gold Nanoparticles Connected with a Carbon Nanotube

Abstract

The scattering problem for dimer consisting of a carbon nanotube (CNT) coated with a thick gold layer everywhere except for a narrow central region is solved in the far infrared range by numerical methods. A nanotube in such a dimer is a low-conductive channel that slows down the flow of charges between two parts of the highly conductive gold coating. Charge transfer plasmon resonance arises at a frequency of 21 THz in the spectrum of the absorption cross section of a dimer with a length of 285 nm and a transverse size of 20 nm. The resonance width is determined mostly by the electron relaxation time in CNTs. It has been shown that the resonant frequency decreases and the absorption cross section at the resonant frequency increases with an increase in the transverse and longitudinal dimensions of the dimer. The presence of a contact resistance between the CNT and the gold layer leads to a shift of the resonant frequency to the low-frequency region and a decrease in the intensity of the absorption peak. The possibility of varying the CNT conductivity by means of electrostatic doping makes it possible to use such dimers as building blocks for metamaterials with controlled resonant properties in the far infrared range.