Amorphous silica studied by high energy x-ray diffraction

The use of hard X-rays (60-300 keV) for diffraction studies of disordered systems gives rise to several advantages compared to the conventionally used energies in the 8 to 20 keV range. Hence, the resolution in direct space becomes better, the correction terms smaller and the much larger penetration lengths make it possible to operate in extreme environments. In general the scattering cross sections also become comparable to the cross sections in neutron diffraction, allowing for direct comparisons between the two techniques, relevant e.g. for partial structure factor determinations. A feasibility study of amorphous silica has been performed at 95 keV, using a Wiggler synchrotron beam-line at HASYLAB and a cylindrical sample of 3 mm diameter. The data is analyzed in terms of a model of the short range order.