Visualizing vibrational normal modes of a single molecule with atomically confined light

Area of Science:

• Chemical Physics
• Molecular Spectroscopy
• Nanotechnology

Background:

• Molecular vibrations are crucial for chemistry and cellular processes but visualizing them requires sub-ångström resolution.
• Traditional optical microscopy is limited by the diffraction limit, preventing direct visualization of molecular normal modes.
• Tip-enhanced Raman spectromicroscopy (TER-SM) offers sub-molecular resolution by enhancing Raman signals with a metallic tip.

Purpose of the Study:

• To achieve ångström-scale spatial resolution for visualizing molecular vibrations.
• To directly image the normal modes of molecular motion.
• To analyze intramolecular charges and currents driven by molecular vibrations.

Main Methods:

• Utilized tip-enhanced Raman spectromicroscopy (TER-SM) integrated with a cryogenic ultrahigh-vacuum scanning tunneling microscope.
• Achieved subatomic separation between a metallic tip and a molecule within the quantum tunneling regime of plasmons.
• Recorded vibrational spectra at the single-molecule level.

Main Results:

• Attained ångström-scale resolution, surpassing the optical diffraction limit.
• Successfully visualized molecular normal modes through direct imaging.
• Atomically resolved intramolecular charges and currents associated with molecular vibrations.

Conclusions:

• TER-SM at the atomic scale provides a new paradigm for near-field optics.
• Direct visualization of molecular vibrations and their dynamics is now achievable.
• This technique opens avenues for understanding chemical transformations and cellular functions at the molecular level.