They then performed a similar Mossbauer spectroscopy experiment  with two absorbers with a substantially different isomer shift to be able to correct the Mossbauer data for vibrations in the rotor system at various rotational frequencies.
For to characterize the acetates (i.e., FeAc and FeAc-FD), we used Mossbauer Spectroscopy, X-Ray Diffraction (XRD), Thermogravimetric Analysis/Differential Scanning Calorimetry (TGA-DSC) and Scanning Electron Microscopy (SEM).
To avoid oxidation of particles during their characterization and to better study the Fe oxidation state of the particles in the solution, they were studied by Mossbauer spectroscopy and the results are shown in Figure 3(a).
In this study, standard samples of ferrous fumarate and gluconate were measured using Mossbauer spectroscopy. The iron valence state and dietary supplements of a Dynabi tablet containing both ferrous fumarate and ferrous gluconate were selected and measured.
Mossbauer Spectroscopy is a highly accurate technique relying on a gamma ray source to determine with extreme precision concentrations of certain types of nuclei within solids in various quantum spin states and valences as well to investigate the structures of biomolecules like proteins.