Single-molecule tip-enhanced Raman spectroscopy of C60 on the Si(111)-(7 × 7) surface.
Phys Chem Chem Phys
; 26(32): 21325-21331, 2024 Aug 14.
Article
em En
| MEDLINE
| ID: mdl-39082139
ABSTRACT
Tip-enhanced Raman spectroscopy (TERS), combined with low-temperature scanning tunnelling microscopy (STM), has emerged as a highly sensitive method for chemical characterization, offering even sub-molecular resolution. However, its exceptional sensitivity is generally limited to molecules adsorbed onto plasmonic surfaces. Here we demonstrate single-molecule TERS for fullerene (C60) adsorbed on the Si(111)-(7 × 7) reconstructed surface. Distinct adsorption geometries of C60 are manifested in the TERS spectra. In addition, we reveal that formation of a molecular-point-contact (MPC) drastically enhances Raman scattering and leads to the emergence of additional vibrational peaks, including overtones and combinations. In the MPC regime, the anti-Stokes peaks are observed, revealing that vibrationally excited states are populated through optical excitation of the MPC junction, whereas showing no significant vibrational heating by current flow via inelastic electron-vibration scattering. Our results will open up the possibility of applying TERS for semiconducting surfaces and studying microscopic mechanisms of vibrational heating in metal-molecule-semiconductor nanojunctions.
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MEDLINE
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2024
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Article