The antenna is considered as the primary means of absorbing electromagnetic waves in space and has its own engineering knowledge, which is very developed and extensive. In general, in order to receive the electromagnetic wave in space, the dimensions of the antenna must be in the order of the size of the input wavelength to its surface. Due to the very low dimensions of nano-sensors, nano-antennas need a very high operating frequency to be usable. The use of graphene greatly helps (...) to solve this problem. Wave propagation velocities in CNTs and GNRs can be up to 100 times slower than vacuum velocities, depending on the physical structure, temperature and energy. Accordingly, the resonant frequency of graphene-based nano-antennas can be twice as low as (nano-carbon) nano-antennas. (shrink)

In general, in order to receive the electromagnetic wave in the space, the dimensions of the antenna must be in the order of the wavelength of the input to its surface. Due to the very small dimensions of nano sensors, nano antennas need to have a very high working frequency to be usable. The use of graphene helps to solve this problem to a great extent. The speed of propagation of waves in CNTs and GNRs can be 100 times lower (...) than its speed in vacuum, and this is related to the physical structure, temperature and energy. Based on this, the resonance frequency of graphene-based nano-antennas can be two orders of magnitude lower than nano-antennas based on nano-carbon materials. It has been mathematically and theoretically proven that a quasi-metallic carbon nanotube can emit terahertz radiation when a time-varying voltage is applied to its sides. One of the most important parameters of any nano antenna is the current distribution on it. This characteristic determines the radiation pattern, radiation resistance and reactance and many important characteristics of the antenna. Despite the possibilities of making nanotubes with a length of several centimeters, it is possible to make electrical conductors with a length-to-width ratio of the order of 10^7. has it. At first glance, nanotube antennas give us the impression that they are similar to Dipole antennas designed in small dimensions. (shrink)

In addition to that, the presence of particles prevents the selective reaction of internal nanotubes, and this issue of purity confuses nanotubes based on their size, type, or use as macromolecular species. Absorption spectroscopy (NIR-Vis-UV) can be used to check the population of the sample or the degree of grouping of the sample. If how to distribute nanotubes by NIR-Vis-UV absorption spectroscopy is desired, the sample should be dispersed or in the form of a thin layer. Optical (...) absorption measurements provide useful information about the electronic properties of SWCNTs, and this information can be used to study covalent and non-covalent interactions between molecules and nanotubes. (shrink)