The possibility of combining NMR with neutron scattering to exploit the spin dependence of the scattering length of a resonant nucleus is investigated. In NMR a pi pulse inverts the magnetization of the resonant nuclei; a second pi pulse restores the magnetization and the sequence could be repeated. The inverting nuclear spins modulate the scattering of polarized neutrons and could provide information similar to that obtainable through isotope substitution. But unlike isotope substitution, slow conformational changes, like those exhibited by proteins, could in principle be followed using NMR modulation. The modulated intensity will be weak unless enhanced nuclear orientation is used. (C) 2003 Elsevier Science B.V. All rights reserved.