The Nuclear Resonant Scattering of synchrotron radiation (NRS SR) is a spectroscopy technique that studies transitions between nuclear energy levels in a hyperfine precision. The method is quite similar to the Mossbauer spectroscopy, even though time spectrums are studied instead of energy spectrums.
Everything begins with a sample being irradiated with synchrotron radiation. Then, the nuclear states of the atoms are excited by absorbing this radiation, and a superposition of the emitted light trains from different energy level transitions is plotted in the so-called time spectrums.
Thanks to the brilliance of the irradiated light, very precise measurements can be done, and resonance is enhanced.
Synchrotron radiation is emitted in pulses of few hundreds of nanoseconds. The time spectrum shows us the log(Intensity) as a function of time since the excitation. Due to the nuclear resonant width in the range of neV, the time scales of relaxation are in the order of nanoseconds and microseconds, and this allows to discriminate from non-resonant scattering process such as fluorescence, with time scales of 10^-15 s usually.
With Fourier analysis of those time spectrums, the frequencies of the different transitions can be obtained. Then, calculations of magnetic hyperfine fields, quadrupole splitting and isomer splitting can be performed.
Another advantage of NRS SR is that is very sensitive to the orientation of magnetization. Depending on the orientation of the incident wave-vector with respect to the magnetic hyperfine field, very different time spectrums can be obtained, and this allows to study several magnetic properties, mostly in low-dimensional structures.