Modification of transition pathways in polarized resonance Raman spectroscopy for carbon nanotubes by highly confined near-field light

We observed a modification of transition pathways in polarized resonance Raman spectroscopy during tip-enhanced Raman spectroscopy (TERS) analysis of metallic carbon nanotubes (CNTs). At a spatial resolution reaching up to the sub-nanometer regime, the signal intensity of the typical D-band is obser...

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Bibliographic Details
Published in:Journal of applied physics 2024-05, Vol.135 (19)
Main Authors: Fujita, Yuto, Hayazawa, Norihiko, Balois-Oguchi, Maria Vanessa, Tanaka, Takuo, Shimizu, Tomoko K.
Format: Article
Language:English
Subjects:
Carbon nanotubes
Electrons
Near fields
Optical transition
Raman spectroscopy
Resonance
Spatial resolution
Spectrum analysis
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Summary:We observed a modification of transition pathways in polarized resonance Raman spectroscopy during tip-enhanced Raman spectroscopy (TERS) analysis of metallic carbon nanotubes (CNTs). At a spatial resolution reaching up to the sub-nanometer regime, the signal intensity of the typical D-band is observed to be even higher than the intensity of the G-band all over the probed CNTs in TERS imaging. The measured D-band is attributed to the non-vertical transitions of electrons in k-space that are facilitated by highly confined near-field light at the tip–sample junction of our scanning tunneling microscope based TERS system. The D-band signal was observed even when the CNTs were excited by light polarized perpendicular to the tube axis that corresponds to electronic excitations between different cutting line numbers of a CNT. By combining the electron pathways brought about by both the near-field light and its polarization, we found a unique optical transition of electrons of CNTs in near-field Raman spectroscopy.
ISSN:0021-8979
1089-7550
DOI:10.1063/5.0204121