Grazing-incidence X-ray diffraction in the study of metallic clusters buried in glass obtained by ion implantation

A novel X-ray technique is described for carrying out structural investigations of metallic nanoparticles buried in glass obtained by ion implantation. The method consists of maximizing the scattering contribution of the cluster-rich layer by working at the critical angle for total external reflection at the implanted-layer-substrate interface. By using the refracted beam as a probe, the diffraction profile of the metallic clusters in very dilute samples can be extracted by a simple subtraction procedure. The new procedure is applied to SiO₂ glasses implanted with Ag ions. The study was performed at the European Synchrotron Radiation Facility. The results indicate that a complete structural investigation can be performed by using highly collimated, very intense synchrotron radiation beams, a grazing-incidence geometry and two-dimensional detectors. The procedure is shown to be very useful for complementing the information from electron techniques (transmission electron microscopy, micro-beam electron diffraction) and X-ray spectroscopic (EXAFS) methods. In particular, the accuracy of the lattice-parameter determination is shown to be a factor of nine better than the accuracy of EXAFS results.