Radial distribution function (RDF) information obtained from amorphous glasses can provide important near and medium range structure information, determination of this information has important consequences for the encapsulation and the long term stability of nuclear waste material.
RDF data has been obtained from samples of waste glass and amorphous quartz. This data was obtained using a Vacuum Generators HB603 FEG-STEM, equipped with a GATAN Digi-PEELS. Post specimen scanning was employed to minimize the effect of spherical aberration that is present in the incident beam rocking mode.
Previous data obtained using the main-scan coils and rocking the incident beam on the specimen, diffraction information collected from out to 16 nm-1. The intensity of the information falls of rapidly as the inverse forth power of the scattering angle, out to the point where the signal to noise of the detector becomes unity. This point is limited by the sensitivity of the detector and the spherical aberration of the objective lens which limits the ultimate collection angle, regardless of the sensitivity of the detection system.