Molecular quantum well at the C60/Au (111) interface

A molecular quantum well is observed in epitaxial thin films of C60 on Au(111). This quantum well is characterized by nearly free-electron-like dispersion in the surface plane and splitting of the electronic band with increasing number of C60 overlayers. The experimental quantum well structure can be well described by tight binding theory with an intermolecular charge transfer integral of β=-33±3 meV, corresponding to a full bandwidth of 400±40 meV. Quantum mechanical calculation based on time-dependent density functional theory provides excellent agreement with this β value. The molecular quantum well is populated by photoinduced electron transfer from the Au substrate and has a transient lifetime of 4 fs<t<20 fs.