Vibronic structure in resonant Auger Raman spectroscopy of large π-conjugated molecules

The photoemission signal of organic thin films and interfaces is studied by investigating a SnPc multilayer film and a SnPc/PTCDA/Ag(1 1 1) heteromolecular film. Significant modifications of the photoemission signal are observed for both films when tuning the photon energy through an absorption edge. This effect can be attributed to electron–vibration coupling. Moreover, we find this effect to be sensitive to intermolecular interaction, even for weak, predominantly non-covalent interaction. Hence, resonant Auger Raman spectroscopy can provide new insight into electron–vibration coupling and intermolecular interaction in organic thin films and at interfaces.