Cross-Section and Measurement Considerations for Polarized Neutron Scattering from NMR Spin-Modulated Systems

We present a development of theoretically predicted cross sections, along with potential measurement scenarios, associated with the scattering of polarized thermal neutrons from target nuclei whose spins are modulated using nuclear magnetic resonance (NMR). Specifically, we investigate the modulation of the polarized differential scattering cross sections under the following two scenarios: (i) Measurements that take place during the time-interval between the application of radio-frequency (RF) pulses that repeatedly impart transverse rotations to selected sets of spin-1/2 target nuclei, and (ii) Measurements that take place during continuous RF irradiation of these nuclei. The aim of this work is to provide foundational knowledge and necessary considerations to explore, and ultimately achieve, the design of instrumentation that would provide enhanced scattering signals from selected nuclei in liquids and solutions by leveraging the use of NMR techniques. We discuss our in-progress calculations which are aimed at evaluating signal-to-noise for a prototypical molecular mixture in the context of NMR/neutron scattering protocols such as those outlined in our recent paper (1).

(1) M. Kotlarchyk and G.M. Thurston, J. Chem. Phys. 145 (2016) 244201