Inorganic Seminar – Prof. Latha Venkataraman (Columbia University)

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1315 Seminar Hall, North Tower
@ 3:30 pm

Title: Physics and Chemistry at the Nanoscale



The past decade has seen tremendous progress in realizing molecular analogues of macroscale electronic components, such as resistors, diodes, switches or transistors, where the molecular circuit property is determined by the chemical structure and physical properties of the metal-molecule-metal junction. This progress has been enabled by the scanning tunneling microscope (STM)-based break-junction technique that my group has pioneered, which facilitates reliable and reproducible measurements of single-molecule devices. In this talk, I describe three areas of on-going research that utilize the break-junction technique:

(1) Long and highly conducting molecular wires are important to create all-organic nanoscale electronic circuits. However, a hinderance to this goal is that the conductance of oligomeric molecular wires decreases exponentially with increasing number of building units. Here, I will present experiments that show how one-dimensional topological insulators building blocks can produce long and highly conducting molecular wires.

(2) Electric fields have been proposed theoretically as having a distinct ability to catalyze chemical reactions through the stabilization of polar or ionic intermediate transition states. I will present recent experimental results that demonstrate solution-based, electric-field driven chemistry using the STM-break junction set-up.

(3) Light emission from plasmonic tunnel junctions is a potential photon source for nanophotonic applications. Such tunnel junctions have been primarily characterized through scattering studies, but electroluminescence offers an exciting alternative from a technological standpoint by removing the need for optical excitation. In this talk, I will present results from our recent work probing the nature of electroluminescence in tunnel junctions.

These results highlight its versatility of the STM-break junction instrument in advancing our understanding of physical and chemical phenomena at the nanoscale. I will end this talk with some comments on the future areas of research using these techniques.

Host: Prof. John Berry