Raman Excitation Mapping of Chirality-Pure Carbon Nanotubes Reveals Photo-Evolution and Interaction with their Surrounding Environments

Published

January 12, 2025

Author(s)

Jeffrey Fagan, Paul Finnie, Jianying Ouyang

Abstract

Raman scattering (RS) is a highly effective metrology for nanomaterial characterization, reporting information on material properties through its combination of possible optical resonances and vibrational modes. Raman excitation mapping (REM) extends this by measuring the RS scattering spectra at multiple excitations to determine wavelength dependencies. Here we use a recently developed, rapid "full-spectrum," technique to obtain REMs and track them over time for chirality-pure films of single-wall carbon nanotubes (SWCNTs). Measurements on (7,6) and (6,5) SWCNT species films show structured excitation profiles for RS from different modes, many over a broad energy range, including some which are not ordinarily investigated. Exposure to light is found to cause dramatic and time-dependent evolution of peak intensities and ratios for many RS modes in the REMs. Tracked over time, most bands decrease gradually while several bands increase with an even-odd split for D band derived modes; excitation profiles change only slightly. Although defects are photo-induced, REM evolution is broadly similar in air and in nitrogen atmosphere. Concurrent changes to photoluminescence (PL) features are also reported. Intrinsic bandgap fluorescence decreases as defect band related RS scattering increases; lower energy PL from the polymer in polymer-wrapped nanotubes samples also appears and grows in intensity as SWCNT bandgap recombination weakens.

Citation

Communications Materials

Volume

6

Pub Type

Journals

Download Paper

https://doi.org/10.1038/s43246-024-00727-6

Local Download

Keywords

Raman spectroscopy, carbon nanotube, resonant excitation, Raman excitation mapping, fluorescence

Citation

Fagan, J. , Finnie, P. and Ouyang, J. (2025), Raman Excitation Mapping of Chirality-Pure Carbon Nanotubes Reveals Photo-Evolution and Interaction with their Surrounding Environments, Communications Materials, [online], https://doi.org/10.1038/s43246-024-00727-6, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=958236 (Accessed September 30, 2025)