Imaging Single-Electron Tunneling at the Nanoscale
Catherine Boisvert, McGill University
Probing the motion of single electrons allows us to explore the quantum properties that define how materials behave at the nanoscale. In the scanning probe microscopy lab at McGill University, we design and build custom non-contact atomic force microscopes (NC-AFM) that make it possible to detect and control individual electronic states. In NC-AFM, an ultra-sharp tip oscillates just above the surface, allowing us to sense forces without ever physically touching the sample. By operating at very low temperatures and applying a bias, we can probe, control, and detect single-electron tunneling events, allowing us to understand fundamental quantum processes that reveal the intrinsic electronic structure of materials.
We have successfully applied this technique to study nanoparticles, molecules, and quantum dots. In doing so, we have mapped quantum energy levels, measured single-electron tunneling rates, and observed transitions between quantized vibronic states at the single-molecule level. Our current goal is to extend these methods to metalloenzymes (enzymes with a metal cofactor), which remain poorly understood despite their fascinating redox properties and great potential for sustainable energy technologies. By probing single-electron tunneling with our low-temperature AFM, we aim to map their quantum energetics and redox coupling to better understand, and eventually engineer, their catalytic activity.
This talk will introduce the fundamentals of NC-AFM, show how we use it to study quantum behavior one electron at a time, and highlight how these tools can help us explore the boundary between physics, chemistry, and biology.
