46
R. Rüffer and A. I. Chumakov
Fig. 1.25 Iron partial
reduced phonon density of
states (DOS) for four
samples of ferropericlase.
The inset shows an enlarged
reduced DOS (Reprinted
from [132] Copyright
(2014), with permission
from Elsevier)
the energy resolution to about 50 μeV is supposed to close the gap and thereby to
enhance capabilities of x-ray techniques.
In addition to the proposed closing of the remaining gap in the energy transfer
region from above, we also anticipate to close the gap from below. In particular,
the Synchrotron Mössbauer Source available at the Nuclear Resonance beamline
at ESRF allows for scattering experiments with an energy transfer from 1 neV to
10 μeV. With an upgraded setup, we plan to reach the energy transfer up to 50 μeV.
Thus, both instruments together allow one to cover entirely the ∼ neV to ∼ meV
energy regime.
Even though the proposed development is related either to momentum-integrated
studies (DOS) (right top panel) or to measurements with only a moderate momentum
resolution ( 0.3 Å
−1 ) (right bottom panel), this can be clearly qualified as entering
no-man’s-land, which will not only help to solve known scientific questions but also
will inevitably lead to new fascinating discoveries in fields of geoscience and glass
physics.
1.7.2.2 Geoscience
Inelastic x-ray scattering and nuclear inelastic scattering are nearly the only tools
to access sound velocity data at extreme conditions such as high pressure and high
temperature. While these measurements are relatively easy for model samples, they
become progressively complicated for systems with large unit cells and lower mean
sound velocities, because the Debye-like parabolic approximation of the DOS is then
only valid for much lower energies.
For example, for some samples of ferropericlase [132], a proper determination of
sound velocities can be achieved within the energy range below 5 meV (Fig. 1.25,
red, orange, and green curves), whereas for other samples this requires precise measurements of the DOS well below 1 meV (Fig. 1.25, blue curve).
Other geophysically meaningful systems like perovskites and wustite require
even better energy resolution. Therefore, an achievement of 50 μeV resolution will
R. Rüffer and A. I. Chumakov
Fig. 1.25 Iron partial
reduced phonon density of
states (DOS) for four
samples of ferropericlase.
The inset shows an enlarged
reduced DOS (Reprinted
from [132] Copyright
(2014), with permission
from Elsevier)
the energy resolution to about 50 μeV is supposed to close the gap and thereby to
enhance capabilities of x-ray techniques.
In addition to the proposed closing of the remaining gap in the energy transfer
region from above, we also anticipate to close the gap from below. In particular,
the Synchrotron Mössbauer Source available at the Nuclear Resonance beamline
at ESRF allows for scattering experiments with an energy transfer from 1 neV to
10 μeV. With an upgraded setup, we plan to reach the energy transfer up to 50 μeV.
Thus, both instruments together allow one to cover entirely the ∼ neV to ∼ meV
energy regime.
Even though the proposed development is related either to momentum-integrated
studies (DOS) (right top panel) or to measurements with only a moderate momentum
resolution ( 0.3 Å
−1 ) (right bottom panel), this can be clearly qualified as entering
no-man’s-land, which will not only help to solve known scientific questions but also
will inevitably lead to new fascinating discoveries in fields of geoscience and glass
physics.
1.7.2.2 Geoscience
Inelastic x-ray scattering and nuclear inelastic scattering are nearly the only tools
to access sound velocity data at extreme conditions such as high pressure and high
temperature. While these measurements are relatively easy for model samples, they
become progressively complicated for systems with large unit cells and lower mean
sound velocities, because the Debye-like parabolic approximation of the DOS is then
only valid for much lower energies.
For example, for some samples of ferropericlase [132], a proper determination of
sound velocities can be achieved within the energy range below 5 meV (Fig. 1.25,
red, orange, and green curves), whereas for other samples this requires precise measurements of the DOS well below 1 meV (Fig. 1.25, blue curve).
Other geophysically meaningful systems like perovskites and wustite require
even better energy resolution. Therefore, an achievement of 50 μeV resolution will