Remarks: The operation of a Surface Science station at the Spanish CRG at ESRF would certainly permit the access to this facility to a significant number of groups already working in problems where SR based techniques play a key role. The construction and operation of a Surface Science station does not require extreme modifications of the beamline layout or specifications, and would be extremely beneficial for an already existing, highly motivated Community of users. Small additional investments could make the research developed in this beamline fully competitive at a worldwide scale. Concerning the potential users of this facility, there already exists a motivated Community which regularly employs SR based techniques. Many of them are also users of the ESRF.

  • X-ray Surface diffraction. (XSD)

    X-ray diffraction has been in the past the most successful technique for the structural analysis of bulk materials. Over the last ten years, the application of x-ray diffraction to Surface Science problems has been developed to a high degree. Thus, it constitutes nowadays one of the preferred techniques to investigate structural problems of surfaces and interfaces. This is due firstly to the high penetration of x-rays, which facilitates the investigation of surfaces and interfaces in conditions otherwise impossible, and in some cases close to real industrial reactors (e.g. high pressures, presence of liquids, etc.). Second, the well-known theoretical background coming from the experience accumulated in the research of bulk materials makes the data analysis relatively straightforward. Finally, the availability of high fluxes (such as those at ESRF) makes it possible to analyze dynamic processes at surfaces and interfaces in a real-time scale. Conventional surface diffraction methods could be directly implemented by making use of a light baby chamber mounted in one of the beamline diffractometers.

  • High Energies Photoemision
  • Thin films (from 10 _ up 10000 _).

    In these systems, in addition to the x-ray diffraction techniques described above, a more specific technique can be used: the x-ray reflectometry. X-ray reflectivity in the range of total reflection is a non-destructive, well-established method since already quite a few years, useful to investigate the thickness and roughness of thin layers. It is extremely sensitive to the actual interface roughness profile of buried interfaces. Since it does not require ultra-high vacuum conditions, it is not a demanding technique in terms of beamtime, as compared to other methods which would provide a comparable information. These properties make it attractive also for conventional quality control of industrial interfaces. As in the previous case, the need of grazing angles (which demand large photon fluxes), and the tunability of SR (which allows to go into the anomalous range), make nowadays of the x-ray reflectivity studies a mainly SR-based technique.