Mössbauer spectroscopy and biophysics

The emission and resonant reabsorption of low‐energy gamma rays in recoilless nuclear transition offers a convenient way to study biochemical reactions. Biological molecules frequently have a transition‐metal atom, such as iron, at the reactive site, and the ${\mathrm{Fe}}^{57}$ nucleus is particularly well suited for precise gamma‐ray spectroscopy. By comparing the Mössbauer spectra of two different forms of one of these molecules, for example the oxidized and reduced forms, we learn something about the electron transfer that takes place in biological systems.