  Optical hyperspectral imaging based on absorption and scattering of photons
at the visible and adjacent frequencies denotes one of the most informative and
inclusive characterization methods in material research. Unfortunately,
restricted by the diffraction limit of light, it is unable to resolve the
nanoscale inhomogeneity in light-matter interactions, which is diagnostic of
the local modulation in material structure and properties. Moreover, many
nanomaterials have highly anisotropic optical properties that are outstandingly
appealing yet hard to characterize through conventional optical methods.
Therefore, there has been a pressing demand in the diverse fields including
electronics, photonics, physics, and materials science to extend the optical
hyperspectral imaging into the nanometer length scale. In this work, we report
a super-resolution hyperspectral imaging technique that simultaneously measures
optical absorption and scattering spectra with the illumination from a
tungsten-halogen lamp. We demonstrated sub-5 nm spatial resolution in both
visible and near-infrared wavelengths (415 to 980 nm) for the hyperspectral
imaging of strained single-walled carbon nanotubes (SWNT) and reconstructed
true-color images to reveal the longitudinal and transverse optical
transition-induced light absorption and scattering in the SWNTs. This is the
first time transverse optical absorption in SWNTs were clearly observed
experimentally. The new technique provides rich near-field spectroscopic
information that had made it possible to analyze the spatial modulation of
band-structure along a single SWNT induced through strain engineering.
