2 Synchrotron-Radiation-Based Energy-Domain Mössbauer …
75
spectrum containing statistical and other errors, the obtained g(E, κ) sometimes
contains the apparent broadening due to the monochromator width. Moreover, special
care should be given to this behavior at low-energy region within the monochromator
width due to the subtraction. In Fig. 2.10, the obtained PDOS from measured NRIS
spectrum is shown using these processes. These procedures are precisely described
in [47, 48]. The area ratio of the elastic peak to the total part in the NRIS spectrum as
shown in the upper spectrum of Fig. 2.10 may be considered as the recoilless fraction,
which is known as the Lamb–Mössbauer factor in Mössbauer spectroscopy. However,
it may be incorrect because coherent forward scattering occurs at the exact nuclear
resonant energy, while such coherent scattering does not, besides the resonant energy,
as discussed in Chap. 1. Although the recoilless fractions are sometimes required to
compare the Mössbauer results, PDOS has much better information and gives the
recoilless fraction value [47].
In eq. (2.12), ¯
n indicates Bose factor ruling the temperature dependence of the
spectrum. Since phonon is boson, phonon creation is proportional to ¯
n + 1, which is
shown in eq. (2.12), while phonon annihilation is proportional to ¯
n. As ¯
n approaches
Fig. 2.10 Phonon density of states shown in the spectrum below is obtained from the measured
nuclear resonant inelastic scattering spectrum shown above [49]
75
spectrum containing statistical and other errors, the obtained g(E, κ) sometimes
contains the apparent broadening due to the monochromator width. Moreover, special
care should be given to this behavior at low-energy region within the monochromator
width due to the subtraction. In Fig. 2.10, the obtained PDOS from measured NRIS
spectrum is shown using these processes. These procedures are precisely described
in [47, 48]. The area ratio of the elastic peak to the total part in the NRIS spectrum as
shown in the upper spectrum of Fig. 2.10 may be considered as the recoilless fraction,
which is known as the Lamb–Mössbauer factor in Mössbauer spectroscopy. However,
it may be incorrect because coherent forward scattering occurs at the exact nuclear
resonant energy, while such coherent scattering does not, besides the resonant energy,
as discussed in Chap. 1. Although the recoilless fractions are sometimes required to
compare the Mössbauer results, PDOS has much better information and gives the
recoilless fraction value [47].
In eq. (2.12), ¯
n indicates Bose factor ruling the temperature dependence of the
spectrum. Since phonon is boson, phonon creation is proportional to ¯
n + 1, which is
shown in eq. (2.12), while phonon annihilation is proportional to ¯
n. As ¯
n approaches
Fig. 2.10 Phonon density of states shown in the spectrum below is obtained from the measured
nuclear resonant inelastic scattering spectrum shown above [49]