Nuclear resonant scattering is like mössbauerspectroscopy a method to determine the hyperfine levels of an isotope. On the contrast with Mössbauer spectroscopy the scattering is not measured in function of energy but in function time.
Nuclear resonant scattering is realized by hitting the target with a broad beam of photons that has a high brilliance. These beams are not continous but consist of bunches of photons with different energies. The difference in energy means that all the hyperfine levels are excited at the same time. These will decay to a lower energy level between the pulses. This will take them a few µs-ns. Some of them will start to interact and give a specific spectrum. AFter this, the spectrum is numerically analyzed out of which, the frequency can be determined. Hence, information of the nucleus can be acquired.
The nuclear resonant scattering is isotopic sensitive and also depends on the orientation of the magnetic field. Making it very usefull in nuclear condenssed matter.