Professor Stephan Link
Biography:
Professor Stephan Link received a Diplom of Chemistry in 1996 from the Technical University of Braunschweig in Germany, followed by graduate work at the Georgia Institute of Technology under the supervision of National Academy of Science member Professor Mostafa El-Sayed. Starting in 2001, Stephan gained postdoctoral research experiences at the Georgia Institute of Technology under Professors Mostafa El-Sayed and Rick Trebino, and then the University of Texas at Austin, where he worked with National Academy of Science member Professor Paul Barbara. In 2006, Stephan started his independent academic career in the Chemistry Department at Rice University. He was promoted to associate professor in 2013 and full professor in 2017. He has a joint appointment in the Department of Electrical and Computer Engineering. Since 2021, he holds the Charles W. Duncan, Jr.-Welch Chair in Chemistry.
Stephan’s research is focused on understanding the effects of heterogeneity on the collective opto-electronic properties of complex nanophotonic nanostructures consisting of metallic nanoparticles coupled to each other as well as to soft molecular or inorganic interfaces. Fundamental questions that his work has addressed are the generation of color through near- and far-field plasmon coupling in 1D nanoparticle assemblies and 2D arrays including chiral nanostructures, the relaxation dynamics of surface plasmons and the role of interfacial charge and energy transfer including under applied electrochemical potentials, the control over nanoscale photothermal heating via hybridized plasmon modes, and the interactions of proteins with nanomaterials. In the process, Stephan’s group employed, advanced, and pioneered several methods capable of monitoring separately the absorption, scattering, and emission of single nanostructures, including for example photothermal absorption spectroscopy, snapshot hyperspectral imaging, and circular and trochoidal differential scattering. Correlation with electron microscopy and tomography as input for electromagnetic simulations typically complements spectroscopic studies to gain detailed insights into structure-function relationships.
Keynote presentation:
Insights from single particle spectroscopy of plasmonic nanostructures
A surface plasmon in a metal nanoparticle is the coherent oscillation of the conduction band electrons leading to both absorption and scattering as well as strong local electromagnetic fields. These fundamental properties have been exploited in many different ways, including surface enhanced spectroscopy and sensing, photothermal cancer therapy, and color display generation. The performance of plasmonic nanoparticles for a desired application not only depends on the particle size and shape, but is tunable through nanoparticle interactions on different length scales that support near- and far-field coupling. Chemical synthesis and assembly of nanostructures are able to tailor plasmonic properties that are, however, typically broadened by ensemble averaging. Single particle spectroscopy together with correlated imaging is capable of removing heterogeneity in size, shape, and assembly geometry and furthermore allows one to separate absorption and scattering contributions. In this talk I will discuss our recent work on understanding the radiative, non-radiative, chiral, and mechanical properties of individual and coupled plasmonic nanostructures including the generation and transfer of hot electrons.