Determine damping rate of the E13 excitonic transition in aligned chiral (6,5) carbon nanotube films

Determine the damping rate γ of the E13 excitonic transition in densely packed, wafer-scale, enantiomer-pure, aligned (6,5) chiral carbon nanotube thin films. This parameter is required to accurately model the second-order nonlinear optical susceptibility χ^(2) near the E13 resonance and reconcile many-body calculations with experimental spectra in the near-infrared region.

Background

The paper presents many-body atomistic calculations that reproduce the observed excitonic enhancement in (6,5)− carbon nanotube films at E11/E12 resonances, with good agreement to experiments using an energy-dependent damping parameter γ(E).

However, the authors note that the calculation appears to overestimate the nonlinearity around the E13 resonance and that the E13 feature is not distinguishable in the linear absorption measurements of the films. As a result, the actual damping rate γ for E13 could not be quantified, leaving a key parameter unknown for accurate modeling of χ2 near this transition.

References

Indeed, the E13 resonance was not distinguishable in the linear absorption spectrum in experiments, making it impossible to evaluate its actual γ.

— Giant Second Harmonic Generation from Wafer-Scale Aligned Chiral Carbon Nanotubes (2407.04514 - Xu et al., 5 Jul 2024) in Main Text, Many-body atomistic calculations discussion following Figure 4