Deep inelastic neutron scattering from freely rotating molecules

The incoherent structure factor for deep inelastic neutron scattering from freely rotating molecules is determined analytically in the framework of the impulse approximation. The single nucleus momentum distributions of the molecule's constituents are then derived and related to the normal mode decomposition of the internal vibrations. A practical example of deep inelastic neutron scattering response function and single-particle momentum distribution for a symmetric top molecule is provided in the case of a freely rotating ammonia molecule.