Transient absorption microscopy studies of the dynamics of single metal and semiconductor nanostructures

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Prof. Gregory V. Hartland of the University of Notre Dame is supported by the Macromolecular, Supramolecular, and Nanochemistry (MSN) Program in the Division of Chemistry to study chemical reactions and the conduction of electrons in metal nanowires. The results from these experiments are important for developing ultra-sensitive mass sensors and circuits that use light instead of electrical current to transport information. If successful, this innovation will allow miniaturization of circuits and sensors to nanoscale dimensions. Both graduate and undergraduate students are participating in this research. The undergraduate students are being recruited to the project from the University of Notre Dame, as well as from nearby four-year colleges in the northern Indiana area that have limited research facilities. The undergraduate and graduate students are also involved in a series of outreach activities that connect to local high school students in the South Bend area. The experiments that are being conducted are providing new information about how nano-materials interact with their environment, and how these interactions are different to those of macroscopic objects. The effects that are being explored include the role of surface bound molecules in mediating energy relaxation in nanomaterials, whether simple solvents such as water behave like viscoelastic solvents at nanoscale dimensions, and the way the environment influences the properties of surface plasmon polaritons - which are electromagnetic magnetic waves that propagate at the surfaces of the nanowires. These measurements are being performed using transient absorption microscopy, which is an experimental technique that allows ultrafast laser measurements to be performed on single nano-objects. Simulations are also being conducted as part of the project. Comparison of the experimental results to the simulations is generating information about the properties of the materials that can be used by other researchers in different areas of science and engineering.