A new UHV diffractometer for surface structure and real time molecular beam deposition studies with synchrotron radiations at ESRF

We describe a new surface X-ray diffractometer, which is optimized to combi ne surface X-ray diffraction (SXRD), absorption spectroscopy (SEXAFS) and g razing incidence small angle scattering (GISAXS). This instrument is partic ularly well suited for real time studies of material elaborated in-situ wit h molecular beam deposition (MBD) techniques. The goniometer allows for lar ge in-plane and out-of-plane momentum transfer with high accuracy. Owing to the flipping mechanism of the sample holder, it can perform absorption exp eriments with polarisation directions normal and parallel to the sample sur face, while keeping a grazing incidence. Several MBD sources as well as com plementary surface sensitive electron techniques (RHEED and Auger spectrosc opy) can be used simultaneously with X-rays. Finally, the samples can easil y be inserted in the X-ray chamber via an UHV transport system and a fast e ntry load-lock module. (C) 1999 Elsevier Science B.V. All rights reserved.