Mössbauer studies of coordination compounds using synchrotron radiation

Nuclear resonant forward scattering (NFS) and nuclear inelastic scattering (NIS) of synchrotron radiation are fairly recent spectroscopic methods for the investigation of complexes containing Mössbauer-active transition metal ions. NFS, which can be regarded as Mössbauer spectroscopy in the time domain, overcomes some limitations of conventional Mössbauer spectroscopy as has been demonstrated especially for bioinorganic compounds. NIS extends the energy range of conventional Mössbauer spectroscopy to the range of molecular vibrations. Since NIS is sensitive only to the mean-square displacement of Mössbauer nuclei it can be used as site-selective vibrational spectroscopy. It complements usefully comparable techniques such as IR or Raman spectroscopy. Examples are given for applications to spin crossover complexes, nitroprusside compounds, heme model complexes and myoglobin.