Single-molecule science with an STM: Ultra-slow, yet ultra-fast chemistry.

The central question of this presentation is: how can we control matter at its fundamental level of single atoms and single molecules? Here I will gently introduce the tool that allows us to control matter at this level, the scanning tunnelling microscope (STM). Then some of the pioneering work using the STM to make atomic-scale adverts, break individual chemical bonds, make bonds etc. At Bath myself and my co-worker Dr Kristina Rusimova, have pushed these techniques by way of state-of-the-art experimental control to explore the journey of an electron from the tip of an STM to instigating a single molecule reaction. All this work is one-molecule-at-a-time (ultra-slow) yet the actual process is through excited state dynamics of the target molecule (ultra-fast). I’ll touch on controlling such excited state dynamics, the influence of intermediate states as energy discriminators, the power of photon output (and a tenuous link to astronomy), and the critical influence of the surface that all this beautiful science plays out on.

• Sloan, P., Palmer, R. Two-electron dissociation of single molecules by atomic manipulation at room temperature. Nature 434, 367–371 (2005). https://doi.org/10.1038/nature03385
• Lock, D., Rusimova, K., Pan, T., R. E. Palmer, P. A. Sloan. Atomically resolved real-space imaging of hot electron dynamics. Nat Communications 6, 8365 (2015). https://doi.org/10.1038/ncomms9365
• K. R. Rusimova, R. M. Purkiss, R. Howes, F. Lee, S. Crampin, and P. A. Sloan, Regulating the femtosecond excited-state lifetime of a single molecule. Science 361,1012-1016(2018). DOI:10.1126/science.aat9688
• Sloan, P.A. and Rusimova, K.R., 2022. A self-consistent model to link surface electronic band structure to the voltage dependence of hot electron induced molecular nanoprobe experiments. Nanoscale Advances, 4(22), pp.4880–4885.: https://doi.org/10.1039/D2NA00644H.
• Victoria Scowcroft, Steve R Davies, Gary Mathlin and Peter A Sloan, Case study of developing an affordable undergraduate observatory, (2023) Phys. Educ. 58 035014