Combined inelastic thermal neutron scattering on the hydrogen atom nucleus of the methane molecule

A quantum-mechanical expression has been derived for the microscopic scattering kernel, which clearly describes the combined inelastic thermal neutron scattering on the rotational-intra vibrational phonons of the methane molecule. When the incident neutron energy is E0≤0.1 eV, it has been established that the influence of the combined inelastic scattering is small and can be practically neglected. However, when E0 > 0.1 eV, then the influence of the combined inelastic scattering increases rapidly with the influence of the incident neutron energy. Then the significant influence on the thermal neutron scattering exerts inelastic scattering on the combination of rotational with intra vibrational phonons of the methane molecule, while the combined inelastic scattering on the intra vibrational phonons is significantly less. In the combination with rotational phonons the biggest influence has threefold degenerated deformed intra vibrational phonons and the least influence has valent intra vibrational phonons. (author)