Relaxation experiments with synchrotron radiation

Relaxation phenomena show up in standard energy-domain Mossbauer spectra vi a line broadening. The evaluation of such spectra is in most cases done by applying the stochastic theory of lineshape mainly developed in the 60's an d 70's. Due to the time structure and the polarization of the synchrotron r adiation nuclear resonance forward scattering in the time domain gives valu able additional information on relaxation mechanisms. We report here mainly on Nuclear Forward Scattering (NFS) experiments, investigating the paramag netic relaxation of high-spin Fe2+ and Fe3+ ions, superparamagnetic relaxat ion and briefly on recent investigations of charge fluctuations in Eu3S4.