The Surface Diffraction Beamline is devoted to structural and dynamical studies of surfaces and interfaces by investigating the diffracted intensities from ordered overlayers or substrate atoms.

The main components of the Beamline are:

  • A Si(111) double crystal monochromator with sagittal focusing achieved by bending the second crystal.
  • Two flat Rh-coated Si mirrors to reject harmonics (<10-4).
  • A first experimental hutch (EH1) equipped with a z-axis diffractometer with its main sample axis vertical, specially suited for horizontal sample surfaces. On the diffractometer it is possible to mount "baby chambers" of a maximum weight of 50 kp. and small cells for solid/liquid or electrochemistry experiments.
  • A UHV/high pressure chamber equipped with an ion gun for sample cleaning, a mass spectrometer and a sample holder that allows to heat the crystals to 1200 K. The chamber base pressure is 1x10 -9 mbar and the maximum pressure is 4 bar. This chamber can be mounted on the vertical diffractometer.
  • A second experimental hutch (EH2) equipped with a z-axis diffractometer with its main sample axis along the horizontal. Coupled to this diffractometer there are two Ultra-High-Vacuum chambers one for sample introduction and the other for analysis. In the last one several K-cells or e-beam cells can be installed for UHV deposition . Also, the sample can be heated up to 1200 K and cooled to 55 K. A Cylindrical Mirror Analyser allows to record Auger spectra in the diffraction position and an ion gun allows to clean the samples.
  • The standard detectors are scintillator point detectors. In both diffractometers an analyser crystal is installed to reduce background. The scattering plane of the analyser can be vertical or horizontal which is useful for polarization analysis of the diffracted beams. Also, a CDD detector can be installed in the detector arm of the horizontal axis diffractometer.