  Dynamical charge transfer processes at molecule-metal interfaces proceed in
the few fs time scale that renders them highly relevant to electronic
excitations in optoelectronic devices. Yet, knowledge thereof is limited when
electronic ground state situations are considered that implicate charge
transfer directly at the fermi energy. Here we show that such processes can be
accessed by means of vibrational excitations, with non-adiabatic
electron-vibron coupling leading to distinct asymmetric line shapes. Thereby
the characteristic time scale of this interfacial dynamical charge transfer can
be derived by using the vibrational oscillation period as an internal clock
reference.
