Computational study of the shift of the G band of double-walled carbon nanotubes due to interlayer interactions

TL;DR

This paper presents a computational analysis of how interlayer interactions in double-walled carbon nanotubes cause shifts in the G band, aligning with experimental observations and aiding nanotube identification.

Contribution

It provides a comprehensive theoretical description of G band shifts due to interlayer interactions, which was previously lacking.

Findings

G band shift decreases with increasing interlayer separation

Shift passes through zero and becomes negative at certain separations

Theoretical predictions agree with experimental data within uncertainty

Abstract

The interactions between the layers of double-walled carbon nanotubes induce measurable shift of the G bands relative to the isolated layers. While experimental data on this shift in free-standing double-walled carbon nanotubes has been reported in the past several years, comprehensive theoretical description of the observed shift is still lacking. The prediction of this shift is important for supporting the assignment of the measured double-walled nanotubes to particular nanotube types. Here, we report a computational study of the G-band shift as a function of the semiconducting inner layer radius and interlayer separation. We find that with increasing interlayer separation, the G band shift decreases, passes through zero and becomes negative, and further increases in absolute value for the wide range of considered inner layer radii. The theoretical predictions are shown to agree with the available experimental data within the experimental uncertainty.