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Abstract
Summary
Single-walled carbon nanotubes (SWCNTs) with a small diameter distribution have been successfully manufactured. The multi-chirality SWCNTs were then separated into two mixtures of metallic and semiconducting SWCNTs. The semiconducting SWCNT mixture was then used to separate semiconducting single chirality SWCNTs. Then, single-chirality SWCNTs, such as (12,1) and (13,2) SWCNTs, were successfully isolated. The metallic SWCNTs with graphene oxide thin films proved to be promising candidates for near-IR laser safety (optical limiting) applications, while doing of chirality enriched semiconducting (12,1) and (13,2) s-SWCNT increase the optical conductivity in the DC limit due to the increase of the density of free carriers.
Abstract
This work evaluated the non-linear optical properties for thin films of a separated low chirality metallic single walled carbon nanotubes (m-SWCNTs) mixed with graphene oxide (GO). The m-SWCNTs were used in weight percentages of 5, 10, and 20%. Using an open and closed Z-scan approach with Nd:YAG laser pulses at 1064 nm (7 ns, 10 Hz), the third order nonlinear susceptibility ( ) was computed using the nonlinear absorption coefficient ( ) and nonlinear refractive index ( ). Because of rising metallicity and partial reduction of GO during laser illumination, all samples display reverse saturable absorption (RSA). As the fraction of m-SWCNTs grows, the nonlinearity response of the GO/m-SWCNT films improves. The GO/m-SWCNTs films’ excellent non-linear optical characteristics make them ideal choices for near-infrared (NIR) laser protection applications.
Transmission experiments on chirality-enhanced semiconducting (12,1) and (13,2) single walled carbon nanotubes (CE-s-SWCNTs) and CE-s-SWCNTs filled with iodine (I2@CE-s-SWCNTs) and bromine (Br2@CE-s-SWCNTs) in a frequency range of 0.1 to 40 THz. The Drude-Lorentz model was used to fit the real part of the optical conductivity. The presence of metallic tube traces in the CE-s-SWCNTs was linked to the Drude (D) term. With iodine and bromine p-doping, the ratio between Drude (D) term and scattering rate ( ) ratio was raised by a factor of 1.13 and 2.35, respectively. This was countered by a large rise in D term, which resulted in an increase in optical conductivity approaching the DC limit.
Furthermore, after doping, the plasmon peak was moved to higher frequencies and gained more spectral weight. According to the estimated optical components, iodine and bromine form acceptor levels that are 0.04 and 0.08 eV above the top of the CE-s-SWCNTs valence band, respectively, displacing the Fermi level. Also some essential spectroscopic characterization techniques as: High-resolution transmission electron microscope (HRTEM), high resolution scanning electron microscope (HRSEM), Raman, and UV-vis spectroscopy were utilized to characterize the samples that have been prepared.