Librational motion in the α phase of solid nitrogen. II. Neutron scattering

An expression is derived for the one-libron coherent inelastic structure factor for neutron scattering by libron modes in the cubic α phase of solid nitrogen. The results of calculations show that for certain modes at the Γ and R points in the first Brillouin zone and for the scattering vector Q along certain directions in reciprocal space the structure factor vanishes. The results are in excellent agreement with the recent inelastic neutron scattering measurements of Kjems and Dolling.