58
M. Seto et al.
SMS
Synchrotron Mössbauer source
RI
Radioisotope
FWHM Full width at half maximum
DAC
Diamond anvil cell
QEGS Quasielastic γ-ray scattering
RC
Radiative coupling
2.1 Introduction
The use of nuclear probes is advantageous for the study of condensed matter because
it enables measurement that would be difficult with electron systems; it gives isotopespecific information for complex compounds. It is possible to attain atomic position
resolution if nuclear probes are implanted at specific positions with atomic resolution such as a special isotope monolayer in an artificial multilayer film made by
molecular beam epitaxy method. The hyperfine interactions between nuclei and electrons are useful for information on the electronic states. Mössbauer spectroscopy,
which uses the recoilless nuclear resonant absorption effect known as the “Mössbauer effect,” is a famous and effective method for the electronic state measurement
using the hyperfine interactions [1]. Mössbauer spectroscopy is a powerful and wellestablished method used in a wide variety of research areas, such as materials, chemical, biological, earth, and fundamental physical sciences. The recoilless fraction
gives lattice dynamics information in addition to electronic state information. Since
nuclear probes are element (isotope)-specific, measurement with very dilute probes
is sometimes possible. Besides, they may even attain atomic layer resolution. Moreover, states of the specific atoms of interest in complex compounds can be elucidated.
Another outstanding feature to be addressed is the narrow width of a nuclear excited
state compared with the resonant excitation energy (e.g., the width of the first nuclear
excited state of
57 Fe is 4.66 neV, while the resonant excitation energy is 14.4 keV).
This feature can be used for the slow dynamics study of resonant atoms in macromolecules, viscous liquids, etc., by observing the broadening of Mössbauer spectra.
With this feature, we can use ultranarrow-width γ-rays as spectroscopic probes for
the slow dynamics study of the sample containing no resonant atoms. This method
is known as “Rayleigh scattering of Mössbauer radiation (RSMR)” [2].
Radioisotope (RI) sources are used in performing Mössbauer spectroscopy, and
the preparation of an RI source for each nuclide to be studied is required. In particular,
the measurement laboratory should be placed near to a reactor or an accelerator that
generates the RI sources with short lives. Mössbauer effect measurement without
preparing the RI sources was achieved using energy-tunable SR as a nuclear excitation source [3]. This achievement made Mössbauer measurement easily accessible for
nuclides other than the limited ones (such as
57 Fe,
119 Sn, and
151 Eu) with long-lifetime
parent RI sources. However, the photon energy range depends on the storage ring
and insertion devices installed (the maximum energy with enough intensity is usually
M. Seto et al.
SMS
Synchrotron Mössbauer source
RI
Radioisotope
FWHM Full width at half maximum
DAC
Diamond anvil cell
QEGS Quasielastic γ-ray scattering
RC
Radiative coupling
2.1 Introduction
The use of nuclear probes is advantageous for the study of condensed matter because
it enables measurement that would be difficult with electron systems; it gives isotopespecific information for complex compounds. It is possible to attain atomic position
resolution if nuclear probes are implanted at specific positions with atomic resolution such as a special isotope monolayer in an artificial multilayer film made by
molecular beam epitaxy method. The hyperfine interactions between nuclei and electrons are useful for information on the electronic states. Mössbauer spectroscopy,
which uses the recoilless nuclear resonant absorption effect known as the “Mössbauer effect,” is a famous and effective method for the electronic state measurement
using the hyperfine interactions [1]. Mössbauer spectroscopy is a powerful and wellestablished method used in a wide variety of research areas, such as materials, chemical, biological, earth, and fundamental physical sciences. The recoilless fraction
gives lattice dynamics information in addition to electronic state information. Since
nuclear probes are element (isotope)-specific, measurement with very dilute probes
is sometimes possible. Besides, they may even attain atomic layer resolution. Moreover, states of the specific atoms of interest in complex compounds can be elucidated.
Another outstanding feature to be addressed is the narrow width of a nuclear excited
state compared with the resonant excitation energy (e.g., the width of the first nuclear
excited state of
57 Fe is 4.66 neV, while the resonant excitation energy is 14.4 keV).
This feature can be used for the slow dynamics study of resonant atoms in macromolecules, viscous liquids, etc., by observing the broadening of Mössbauer spectra.
With this feature, we can use ultranarrow-width γ-rays as spectroscopic probes for
the slow dynamics study of the sample containing no resonant atoms. This method
is known as “Rayleigh scattering of Mössbauer radiation (RSMR)” [2].
Radioisotope (RI) sources are used in performing Mössbauer spectroscopy, and
the preparation of an RI source for each nuclide to be studied is required. In particular,
the measurement laboratory should be placed near to a reactor or an accelerator that
generates the RI sources with short lives. Mössbauer effect measurement without
preparing the RI sources was achieved using energy-tunable SR as a nuclear excitation source [3]. This achievement made Mössbauer measurement easily accessible for
nuclides other than the limited ones (such as
57 Fe,
119 Sn, and
151 Eu) with long-lifetime
parent RI sources. However, the photon energy range depends on the storage ring
and insertion devices installed (the maximum energy with enough intensity is usually