Electron-induced excitation of vibrations of Ce atoms inside a C ₈₀ cage

Inelastic electron tunneling spectroscopy of Ce₂@C₈₀ 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 C₈₀ cage. The electron-vibration interaction in Ce₂@C₈₀ is unusually high, inducing a pronounced zero-bias anomaly in differential conductance of Ce ₂@C₈₀. Our observations show that the atoms encapsulated in fullerene cages can actively participate in determining the properties of molecular junctions.