Absorption of acoustic phonons in Fluorinated Carbon Nanotubes with non-parabolic, double periodic band

TL;DR

This study theoretically compares acoustic phonon absorption in fluorinated and undoped carbon nanotubes, revealing fluorination reduces absorption and alters electronic properties, with absorption ratios decreasing as temperature rises.

Contribution

It provides a theoretical analysis of how fluorination affects acoustic phonon absorption and electronic properties in carbon nanotubes, highlighting the transition from metallic to semiconductor behavior.

Findings

Fluorination decreases phonon absorption in carbon nanotubes.

Absorption ratio between SWNT and F-CNT decreases with temperature.

F-CNT exhibits less absorption due to weakened walls and altered electronic properties.

Abstract

We studied theoretically the absorption of acoustic phonons in the hypersound regime in Fluorine modified Carbon Nanotube (F-CNT) $\Gamma_q^{F-CNT}$ and compared it to that of undoped Single Walled Nanotube (SWNT) $\Gamma_q^{SWNT}$. Per the numerical analysis, the F-CNT showed less absorption to that of SWNT thus $\vert\Gamma_q^{F-CNT}\vert < \vert\Gamma_q^{SWNT}\vert $. This is due to the fact that Fluorine is highly electronegative and weakens the walls of the SWNT. Thus, the $\pi$-electrons associated with to the Fluorine which causes less free charge carriers to interact with the phonons and hence changing the metallic properties of the SWNT to semiconductor by the doping process. From the graphs obtained, the ratio of hypersound absorption in SWNT to F-CNT at $T = 45K$ is $\frac{\Gamma_{(SWNT)}}{\Gamma_{(F-CNT)}}\approx 29$ whilst at $T = 55K$, is $\frac{\Gamma_{(SWNT)}}{\Gamma_{(F-CNT)}}\approx 9$ and at $T = 65K$, is $\frac{\Gamma_{(SWNT)}}{\Gamma_{(F-CNT)}}\approx 2$. Clearly, the ratio decreases as the temperature increases.