Probing Chemistry at the Angstrom-Scale via Scanning Tunneling Microscopy Combined Tip-Enhanced Raman Spectroscopy

This method, further aided by the benefits of ultrahigh vacuum, is uniquely capable of controlling localized plasmons via an atomistic approach. We are able to obtain (1) single-molecule chemical identification [1]; (2) quantum characterization of adsorbate-substrate interactions at the single chemical bond level [2-4]; (3) atomic-scale insights into the oxygen reactivity on surfaces [5,6]; (4) local strain effects in an organic/2D materials heterostructure [7]. By investigating single molecules, superstructures, 2D materials lattices, and the adsorption orientations obtained from the vibrational modes, we extract novel surface information at an unprecedented spatial (< 1 nm) and energy (< 10 wavenumber) resolution. Another application of localized surface plasmons is to achieve site-selective chemical reactions at sub-molecular scale. We recently selectively and precisely activated multiple chemically equivalent reactive sites one by one within the structure of a single molecule by scanning probe microscopy tip-controlled plasmonic resonance [8]. Our method can interrogate the mechanisms of forming and breaking chemical bonds at the Ångström scale in various local environments, which is critical in designing new atom- and energy-efficient materials and molecular assemblies with tailored physical and chemical properties.
Reference:
[1] Nano Letters, 19, 3267-3272 (2019).
[2] ACS Nano, 18, 32118-32125 (2024).
[3] ACS Nano, 19, 15363-15370 (2025).
[4] Chem, 11, 202290 (2025).
[5] Nature Communications, 13, 1796 (1-9) (2022).
[6] Angewandte Chemie International Edition, 62, e202306590 (2023).
[7] Journal of the American Chemical Society, 143, 38, 15624-15634 (2021).
[8] Journal of the American Chemical Society, 144, 5, 2051-2055 (2022).