Issue 32, 2024

Single-molecule tip-enhanced Raman spectroscopy of C60 on the Si(111)-(7 × 7) surface

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.

Graphical abstract: Single-molecule tip-enhanced Raman spectroscopy of C60 on the Si(111)-(7 × 7) surface

Supplementary files

Article information

Article type
Communication
Submitted
30 Apr 2024
Accepted
21 Jul 2024
First published
31 Jul 2024
This article is Open Access
Creative Commons BY-NC license

Phys. Chem. Chem. Phys., 2024,26, 21325-21331

Single-molecule tip-enhanced Raman spectroscopy of C60 on the Si(111)-(7 × 7) surface

B. Cirera, S. Liu, Y. Park, I. Hamada, M. Wolf, A. Shiotari and T. Kumagai, Phys. Chem. Chem. Phys., 2024, 26, 21325 DOI: 10.1039/D4CP01803F

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