Mössbauereffecten

The Mössbauer effects, collectively known as the Mössbauer effect, describe the recoil-free emission and absorption of gamma rays by atomic nuclei bound in a solid. Discovered by Rudolf Mössbauer in 1958, the effect enables resonant, Doppler-free spectroscopy with exceptionally high energy resolution and has become a standard tool in solid-state physics, chemistry, and geology.

In a crystal lattice, momentum can be transferred to the entire lattice, suppressing recoil so a gamma quantum can be emitted or absorbed without energy loss. The fraction of recoil-free events is described by the Lamb–Mössbauer factor, which depends on temperature and the lattice vibrational spectrum.

Mössbauer spectroscopy analyzes hyperfine interactions that split the gamma line. The isomer shift reflects electron density at the nucleus and reveals oxidation state and bonding; quadrupole splitting indicates electric field gradients from non-spherical charge distributions; magnetic hyperfine splitting reveals internal magnetic fields.

The most widely used Mössbauer transition is 57Fe at 14.4 keV, typically sourced from 57Co decaying to 57Fe. Other Mössbauer-active nuclei include 119Sn, 121Sb, 129I, and 151Eu, among others, providing insights for a range of chemical environments.

Applications span metallurgy, catalysis, geology, and materials science, including studies of iron-containing phases in steels and oxides, magnetic materials, mineral identification, valence state changes, and phase transitions as a function of temperature, pressure, or composition.

Limitations and practical considerations include the need for suitable isotopes with narrow gamma transitions and solid samples; interpretation relies on models of hyperfine interactions and often complementary measurements. Experiments commonly employ Doppler-driven energy scanning with a moving gamma source or absorber.