Femtosecond time resolved photoelectron imaging has been applied to the electronic relaxation of an ethylene-like molecule, tetrakis dimethylamino ethylene, excited to a ππ valence state. This method has an unprecedented efficiency for the observation of the states traversed by the wavepacket created on the initial state. We infer here that electronic relaxation gains efficiency by the mediation of nearby Rydberg states present at this excitation energy. The bulkiness of the molecule allows also the observation of an oscillatory wavepacket movement created on coordinates perpendicular to the relaxation coordinates.
