The Advanced Photon Source
a U.S. Department of Energy Office of Science User Facility

NST Seminar: Angstom Scale Chemical Analysis via Scanning Tunneling Microscopy and Tip-Enhanced Raman Spectroscopy

Type Of Event
Seminar
Location
440/A105-A106
Building Number
440
Room Number
A105-A106
Speaker
Nan Jiang, University of Illinois at Chicago
Host
Saw Wai Hla
Start Date
07-12-2019
Start Time
11:00 a.m.
Description

Abstract:

My research group is broadly interested in spectroscopically determining how local chemical environments affect single molecule behaviors. We focus on highly heterogeneous systems such as molecular self-assembly and bimetallic catalysis, developing and using new imaging and spectroscopic approaches to probe structure and function on nanometer length scales. This talk will focus on 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 obtaining (1) single molecules chemical identification; (2) the molecular mechanism of chemical bond formation under near-surface conditions using self-assembly concepts; (3)adsorbate-substrate interactions in the ordering of molecular building blocks in supramolecular nanostructures. By investigating substrate structures, superstructures, and the adsorption orientations obtained from vibrational modes, we extract novel surface-chemistry information at an unprecedented spatial (<1nm) and energy (<10 wavenumber) resolution. We are able to interrogate the impact of changes in the chemical environment on the properties of supramolecular nanostructures, and thereby lay the foundation for controlling their size, shape and composition.

 

07.10.2019

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