Chemistry Reference
In-Depth Information
The past environmental conditions characterized by low pH inferred from the
detection of jarosite at Meridiani Planum have implications for the suitability for
life at Meridiani Planum. While microbial populations on Earth have adapted to
low pH levels, they would have challenged prebiotic chemical reactions thought to
have played a role in the origin of life on Earth [
92
].
2.4 Conclusion and Outlook
The examples of chemical applications of Mössbauer spectroscopy discussed in
this Tutorial Lecture have mostly been selected from the authors' own research
work and can, of course, only provide the reader with ideas about the kind of
problems that can be solved with this nuclear resonance technique. Since the
discovery of recoilless nuclear resonance absorption (''Mössbauer effect'') by the
german physicist Rudolf Mössbauer more than fifty years ago, Mössbauer spec-
troscopy has developed to a powerful tool in solid state research, making use of
more than twenty ''Mössbauer-active'' nuclides from the list of more than fourty
isotopes for which the Mössbauer effect has been observed [
17
]. Mössbauer
spectroscopy has mostly been employed in conjunction with other physical tech-
niques in order to gain more conclusive information in certain studies, but also in
cases where certain problems could not be solved by other techniques.
Two important technical developments have recently opened new pathways in
Mössbauer spectroscopy and will undoubtedly play a significant role in future: (1) The
realization of a miniaturized portable Mössbauer spectrometer (MIMOS) for material
characterization outside the laboratory as briefly described above, and (2) the use of
synchrotron radiation for observing nuclear resonance fluorescence. The latter was
initiated by E. Gerdau et al. in 1985 who proposed an unconventional Mössbauer
technique using synchrotron radiation to observe nuclear resonance in two ways:
Nuclear forward scattering (NFS) to study hyperfine interactions, as obtained with
conventional Mössbauer spectroscopy, and nuclear inelastic scattering (NIS) to
investigate local phonon spectra (partial density of states, PDOS) at the Mössbauer
probe nucleus [
93
]. NFS and NIS, are certainly on their way to a great future [
94
].
Acknowledgments We thank the Deutsche Forschungsgemeinschaft, the Fonds der Chemischen
Industrie and the Fonds National de la Recherche Scientifique (FNRS) for financial support.
Dedicated to Professor Wolfgang Kaim on the occasion of his 60th birthday.
Message to the Next Generation
Looking back over nearly five decades of working with Mössbauer spectroscopy in
combination with other physical methods for characterizing inorganic compounds,
mainly those exhibiting electronic structure phenomena, I can now state with great
