Mössbauer effect is the recoil-free emission and resonant absorption of gamma () rays from the nuclei of certain radioactive isotopes such as 57 Fe. These -rays, as emitted, do not lose energy from the recoil of the nuclei because the recoil momentum due to their emission or absorption is taken up by the whole bulky sample rather than by the emitting or absorbing nucleus itself. Under such conditions, the nuclei are bound rigidly in the lattice of a crystal, and the energy of recoil is negligible. Spectra based on Mössbauer effect have found numerous applications in studying the valence of an element in a chemical compound, the state of the irons and their electronic structure, as well as structural and magnetic properties of magnetic bulk and thin-film materials.

The Mössbauer effect was first reported by Rudolph Mö...