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We review some aspects of the investigation of surface systems with soft X-rays. Examples are presented, showing how core level spectroscopies provide detailed information on the structure, bonding and chemistry of adsorbates and thin layers on surfaces. Core level spectroscopies employed at high brilliance synchrotron light sources allow furthermore access to electron dynamics in the attosecond domain, as we demonstrate for the core hole clock method.

The bonding configuration and electronic structure of ethylene oxide adsorbed on Si(100)-(2 × 1) is investigated with fully polarization resolved X-ray absorption spectroscopy as well as with core level and valence band photoemission spectroscopy. Ethylene oxide is found to adsorb via a ring-opening reaction, where the molecule forms a five-membered ring together with the silicon surface dimer atoms inserting between a carbon and the oxygen atom. In the resulting geometry, the molecule is tilted out of the surface plane.

We review some aspects of the investigation of surface systems with soft X-rays. Examples are presented, showing how core level spectroscopies provide detailed information on the structure, bonding and chemistry of adsorbates and thin layers on surfaces. Core level spectroscopies employed at high brilliance synchrotron light sources allow furthermore access to electron dynamics in the attosecond domain, as we demonstrate for the core hole clock method.

Abstract: We review some aspects of the investigation of surface systems with soft X-rays. Examples are presented, showing how core level spectroscopies provide detailed information on the structure, bonding and chemistry of adsorbates and thin layers on surfaces. Core level spectroscopies employed at high brilliance synchrotron light sources allow furthermore access to electron dynamics in the attosecond domain, as we demonstrate for the core hole clock method.

Phthalocyanines (Pcs) are capable of converting sunlight into electric energy when adsorbed on TiO2in a dye-sensitized solar cell. Of special interest in this type of cell is the energy level alignment as well as how molecules adsorb on the surface as it determines the output of the cell. We investigated the FePc−TiO2(110) interface using scanning tunneling microscopy, synchrotron-based photoelectron spectroscopy, and X-ray absorption spectroscopy. We found a strong coupling of the first-layer FePc to the substrate resulting in an alteration of the electronic structure and charge transfer from the molecules. The FePc in the second layer is not severely affected by the bonding to the surface and has bulk-like electronic properties. The growth of FePc thin films proceeds in a layer plus island mode, and the molecular plane is parallel to the surface. The energy level alignment at the interface is determined, and the lowest unoccupied molecular orbital is found above the conduction band minimum of the oxide substrate.