Core-hole induced misalignment between Van-Hove singularities and K-edge fine structure in carbon nanotubes
We investigate the relationship between the K-edge fine structure of isolated single-wall carbon nanotubes (SWCNTs) and the Van Hove singularities (VHSs) in the conduction band density of states. To this end, we model X-ray absorption spectra of SWCNTs using the final-state approximation and the Bet...
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Main Authors | , , , , , , |
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Format | Journal Article |
Language | English |
Published |
26.09.2024
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Subjects | |
Online Access | Get full text |
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Summary: | We investigate the relationship between the K-edge fine structure of isolated
single-wall carbon nanotubes (SWCNTs) and the Van Hove singularities (VHSs) in
the conduction band density of states. To this end, we model X-ray absorption
spectra of SWCNTs using the final-state approximation and the Bethe-Salpeter
equation (BSE) method. Both methods can reproduce the experimental fine
structure, where the BSE results improve on peak positions and amplitude
rations compared to the final-state approximation. When the fine structure in
the modeled spectra is related to the VHSs significant differences are found.
We suggest that these differences arise due to modifications of the core
exciton wavefunctions induced by the confinement along the circumference.
Additionally, we analyze the character of core excitons in SWCNTs and find that
the first bright excitons are Frenkel excitons while higher-lying excitons are
charge resonance states. Finally, we suggest that the qualitative picture based
on VHSs in the density of states holds when there is a large energy gap between
successive VHSs. |
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DOI: | 10.48550/arxiv.2409.17619 |