Our research focuses on materials at the single-molecule and atomic scale, investigating how local environments govern the physical and chemical properties of functional materials, nanostructures, and surface-supported molecular systems with Ångström-scale resolution. Tip-Enhanced Raman Spectroscopy (TERS) uniquely integrates the atomic spatial resolution of Scanning Tunneling Microscopy (STM) with the chemical sensitivity of Raman spectroscopy. By utilizing a plasmonically active scanning probe, the Raman signal at the tip-sample junction is greatly enhanced, enabling single- molecule probing. When combined with ultrahigh vacuum conditions, this approach allows atomistic control of localized surface plasmons with exceptional stability and precision. Using TERS, we have achieved: (1) single-molecule chemical identification;1 (2) quantum-level characterization of adsorbate-substrate interactions down to individual chemical bonds;2-4, (3) atomic-scale insights into the oxygen reactivity on surfaces;5, 6 (4) direct measurements of local strain effects in organic/2D materials heterostructures.7 By probing single molecules, molecular superstructures, and 2D material lattices, we extract previously inaccessible materials information with unprecedented spatial (<1 nm) and energy (<10 cm⁻¹) resolution. Beyond spectroscopy, localized surface plasmons enable materials transformation through site-selective chemistry at the submolecular 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. S. Mahapatra, Y. Ning, J. F. Schultz, L. Li, J. -L. Zhang, N. Jiang, “Angstrom Scale Chemical Analysis of Metal Supported Trans- and Cis-Regioisomers by Ultrahigh Vacuum Tip-Enhanced Raman Mapping”, Nano Letters, 19, 3267-3272 (2019).
2. L. Li, S. Mahapatra, J.F. Schultz, X. Zhang, N. Jiang, “Chemically Interrogating N-Heterocyclic Carbenes at the Single-Molecule Level Using Tip-Enhanced Raman Spectroscopy”, ACS Nano, 18, 32118-32125 (2024).
3. L. Li, J.F. Schultz, S. Mahapatra, D. Liu, X. Zhang, N. Jiang, “Optical Spectroscopic Probing and Atomic Visualization of the Motion of N-Heterocyclic Carbenes on Ag(111)”, ACS Nano, 19, 15363-15370 (2025).
4. L. Li, S. Mahapatra, J. F Schultz, X. Zhang, N. Jiang, "Single-molecule spectroscopic probing of N-heterocyclic carbenes on a two-dimensional metal", Chem, 11, 202290 (2025).
5. L. Li, J. F. Schultz, S. Mahapatra, Z. Lu, X. Zhang, and N. Jiang, “Chemically identifying single adatoms with single-bond sensitivity during oxidation reactions of borophene”, Nature Communications, 13, 1796 (1-9) (2022).
6. L. Li, J.F. Schultz, S. Mahapatra, X. Liu, X. Zhang, M. Hersam, N. Jiang, "Atomic-Scale Insights into the Interlayer Characteristics and Oxygen Reactivity of Bilayer Borophene", Angewandte Chemie International Edition, 62, e202306590 (2023).
7. L. Li, J. F. Schultz, S. Mahapatra, X. Zhang. X. Liu, C. Shaw, M. Hersam, N. Jiang, “Probing interfacial interactions in an organic/borophene heterostructure with angstrom resolution”, Journal of the American Chemical Society, 143, 38, 15624-15634 (2021).
8. S. Mahapatra, J. F. Schultz, L. Li, X. Zhang, N. Jiang, “Controlling Localized Plasmons via an Atomistic Approach: Attainment of Site-Selective Activation inside a Single Molecule”, Journal of the American Chemical Society, 144, 5, 2051-2055 (2022).