S. Müllegger et al., Phys. Rev. Lett. (2014)
Oscillations in a cantileverlike chain of molecules. An STM tip was used to image chains of BPDA molecules on a gold surface at different temperatures. (Left) A chain of seven molecules holds still at 5 K, but oscillates back and forth (the fundamental mode) at 25 K. (Right) A higher harmonic of the oscillation can be seen in slightly longer chains (twelve molecules).