Electron-induced excitation of vibrations of Ce atoms inside aC80cage

Inelastic electron tunneling spectroscopy of Ce${}_{2}$@C${}_{80}$ dimetallofullerenes reveals a low-energy inelastic excitation that is interpreted using ab initio calculations and associated with the movements of encapsulated Ce atoms inside the ${\mathrm{C}}_{80}$ cage. The electron-vibration interaction in Ce${}_{2}$@C${}_{80}$ is unusually high, inducing a pronounced zero-bias anomaly in differential conductance of Ce${}_{2}$@C${}_{80}$. Our observations show that the atoms encapsulated in fullerene cages can actively participate in determining the properties of molecular junctions.