Multiple-scattering x-ray absorption analysis of quartzlike, rutilelike, and amorphous germanium dioxide

The local structure of germanium dioxide, in its crystalline (quartzlike and rutilelike) and amorphous (a-GeO2) solid phases, has been investigated by means of x-ray absorption spectroscopy (XAS). The short-range distance and angular distributions have been determined by modeling the experimental spectra with multiple-scattering contributions associated with selected n-body atomic configurations. Even for a-GeO2, the experimental x-ray absorption signal ends up being significantly affected by the intra-tetrahedral (O-(GE) over cap -O) and inter-tetrahedral (Ge-(O) over cap -Ge) angle distributions. Results from the present XAS structural refinements, including experimental determination of the local bond-angle distributions, are compared with previous experiments and molecular dynamics simulations.