A peer-reviewed single-molecule experiment flipped bowl-shaped sumanene on gold using an atomic force microscope. The measured mechanical work fell below the calculated barrier for the molecule without the probe. Calculations link this to attraction from the tip's larger body, which changes the energy landscape during the transformation under controlled surface conditions.
A single peer-reviewed experiment used an atomic force microscope to invert sumanene, a bowl-shaped carbon molecule, on a gold surface. The probe's approach pushed the bowl into its opposite orientation. Images before and after manipulation distinguished this inversion from rotation of the entire molecule. The force measured during approach and withdrawal traced a loop, whose area gives the mechanical work dissipated in the transformation.[1]
One measured transformation dissipated approximately 0.50 electronvolts, compared with a calculated barrier near 0.67 electronvolts for the surface-bound molecule without the tip. Calculations indicate that attraction from the probe's larger body stabilizes the transition state. The nearby apex alone does not capture the whole effect. The energy landscape changes as the probe moves, alongside the short-range repulsion that drives inversion.[1]
The measurements took place at 4.8 kelvin under ultrahigh vacuum. Simulations with different surface-cell sizes changed the calculated barrier, with extrapolation giving approximately 0.61 electronvolts for an isolated molecule. Different probe tips helped examine how geometry affects the work. The result concerns controlled molecular manipulation, with reversible energy exchange during approach and withdrawal distinct from the dissipated portion.[1]
