Real-Time Video Imaging of Mechanical Motions of a Single Molecular Shuttle

Miniatured machines has open up a new dimension of chemistry, studied usually as an average over numerous molecules or for a single molecule bound on a robust substrate. Mechanical motions at a single molecule level, however, are under quantum control, strongly coupled with fluctuations of its environment -- a system rarely addressed because an efficient way of observing the nanomechanical motions in real time is lacking. Here, we report sub-ms sub-Å precision in situ video imaging of a single fullerene molecule shuttling, rotating, and interacting with a vibrating carbon nanotube, using an electron microscope, a fast camera, and a denoising algorithm. We have realized high spatial precision of distance measurement with the standard error of the mean as small as ± 0.01 nm, and revealed the rich molecular dynamics, where motions are non-linear, stochastic and often non-repeatable, and a work and energy relationship at a molecular level previously undetected by time-averaged measurements or microscopy.