Condensed Matter Seminar: Prof. Nan Jiang, University of Illinois Chicago


Location: 118 Nieuwland Science Hall (View on map )

Probing Physical and Chemical Properties at the Ångström-Scale via Scanning Tunneling Microscopy and Tip-Enhanced Raman Spectroscopy
Prof. Nan Jiang
Department of Chemistry
University of Illinois Chicago
My research group is interested in investigating how local environments affect single-molecule and nanostructure properties with Ångström scale resolution. This talk will start with Tip-Enhanced Raman Spectroscopy (TERS), which affords the spatial resolution of traditional Scanning Tunneling Microscopy (STM) while collecting the chemical information provided by Raman spectroscopy. By using a plasmonically-active material for our scanning probe, the Raman signal at the tip-sample junction is incredibly enhanced, allowing for single-molecule probing. 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) adsorbate-substrate interactions in the ordering of molecular building blocks in supramolecular nanostructures; 2 (3) atomic-scale insights into the oxygen reactivity of 2D materials; 3, 4 (4) local strain effects in an organic/2D materials heterostructure. 5 By investigating substrate structures, superstructures, 2D materials lattices, and the adsorption orientations obtained from vibrational modes, we extract novel surface-chemistry 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. 6 Our method can interrogate the mechanisms of forming and breaking chemical bonds at the Ångström scale in various chemical environments, which is critical in designing new atom- and energy-efficient materials and molecular assemblies with tailored physical and chemical properties.

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. J. F. Schultz, L. Li, S. Mahapatra, C. Shaw, X. Zhang, N. Jiang, “Defining Multiple Configurations of Rubrene on a Ag(100) Surface with 5 Angstrom Spatial Resolution via Ultrahigh Vacuum Tip-Enhanced Raman Spectroscopy”, The Journal of Physical Chemistry C, 124, 2420-2426 (2020).
3. 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).
4. L. Li, J.F. Schultz, S. Mahapatra, X. Liu, X. Zhang, M. Hersam, N. Jiang, &quot;Atomic-Scale Insights into the Interlayer Characteristics and Oxygen Reactivity of Bilayer Borophene&quot;, Angewandte Chemie International Edition, 2023,
5. 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).
6. S. Mahapatra, J. F. Schultz, L. Li, X. Zhang, and 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).