NRS stands for Nuclear Resonant Scattering. It is an experimental method that is useful to probe energetic levels of hyperfine atomic systems in time-domain. With bunches of radiation one excites the sample and records the spectrum over time.
Exciting the system causes the hyperfine oscillation levels to simultaneously decay. This phenomenon takes shape of some quantum beats. The method is useful to observe the oscillations to vanish as a function of scattering length (a distance photon takes after the process of scattering). It is applicable also for rotation angle- and magnetic field intensity H-dependence.
NRS method allows to map the spin structure in the sample of a layered system. As hyperfine spectroscopy with time-resolution, NRS depends on exciting the hyperfine energetic levels. It is important to mention that resonant methods (ME, NRS, NMR) are nuclear-levels sensitive, while methods such as XAS, ARPES, XPS are probing the energetic levels of the electronic structure.