X-ray photon-stimulated desorption of ions from semiconductor surfaces has been studied in detail by use of synchrotron radiation with photon energies between 2.8 and 12 keV. The excitation process and the desorption site was identified by means of time-of-flight spectroscopy in combination with X-ray standing waves. Experiments were performed for submonolayers of CsCl on Si(111), Ge on H:Si(111)-1×1, as well as on clean Si(111)-7×7. © 1999 Elsevier Science B.V. All rights reserved.