Assaying of hydrogenous materials using nuclear resonance fluorescence

Methods and systems are disclosed wherein neutrons are produced by a photon induced process 2D(γ,n) and the ensuing neutrons are thermalized and captured by hydrogen producing a 2.223 MeV gamma that is used to identify and quantify the presence of hydrogen and which, when combined with NRF signals from certain isotopes, can be used to establish the nature of a hydrogenous compound or a mixture of hydrogenous materials or a mixture of hydrogenous materials with other non-hydrogenous materials. The method is useful to establish, e.g., the presence and quantification of explosives, toxic substances and general contraband as well as the flow of materials in a production line or shipping venue.