Neutron scattering from vitreous silica. Pt. 1

The paper is the first in a series of five reporting a comprehensive set of neutron diffraction experiments on vitreous silica. A theoretical foundation is presented for the scattering of neutrons by amorphous solids and a measurement of the total cross-section of vitreous silica is described in the energy range 1 to 1660 meV. The data are consistent with a very small incoherent scattering cross-section (sigmasup(inc)sub(SiO2)<0.1 barn) and have been Fourier transformed to yield the real space radial density function R(r). Values obtained for the Si-O [(1.62+-0.01) A] and O-O [(2.64+-0.01) A] distances are in good agreement with the results of conventional diffraction experiments. The results demonstrate the usefulness of total cross-section structural measurements, which could prove particularly valuable for kinetic studies or in the case of hostile sample environments (e.g. very high temperatures and pressures). (orig.)