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M. Seto et al.
this method can be combined with X-ray optical techniques because of the very low
angular divergence of SR and its highly polarized property. For example, the total
reflection technique, which occurs in the condition of typically some milliradians,
can be effectively combined and applied to Mössbauer spectroscopy of thin films.
2.2.2 Instrumentation
In principle, the components other than SR are as follows: monochromator(s), transmitter, scatterer, a velocity-controlling instrument (Mössbauer transducer), and a
timing detector. A schematic diagram is shown in Fig. 2.3. First, SR from a beamline
undulator passes through a pair monochromator Si crystal. The normal beamline
monochromator usually determines the energy of SR with the bandwidth of some
electron volts. This energy width is much wider than the hyperfine structure to analyze
in the transmitter or scatterer in the figure. The energy modulation by the hyperfine
structure is typically below some 10
−6 eV. Thus, the energy profile of SR from the
monochromator is virtually white, as shown in Fig. 2.3b. After the monochromator,
the SR penetrates the transmitter in Fig. 2.3a. A sample under study or an energy
reference substance at SR-based Mössbauer spectra is positioned as the transmitter.
In fact, one of these two should be arranged as the transmitter, and the other should
be as the scatterer. The difference between them is described later in this section.
Fig. 2.3 A schematic diagram of the instrumentation and mechanism of SR-based Mössbauer spectroscopy. a The arrangement of instruments. b The energy profile of SR from the monochromator;
c The profile of SR behind the transmitter, which has a resonant energy E; d The profile of the
scattering from the scatterer, which has a resonant energy E s controlled by the velocity transducer
in the case of E s = E t in the upper panel and E s = E t in the lower panel; e The detected intensity
dependence on the scatterer’s velocity. At the velocity v t , E s = E t is satisfied
M. Seto et al.
this method can be combined with X-ray optical techniques because of the very low
angular divergence of SR and its highly polarized property. For example, the total
reflection technique, which occurs in the condition of typically some milliradians,
can be effectively combined and applied to Mössbauer spectroscopy of thin films.
2.2.2 Instrumentation
In principle, the components other than SR are as follows: monochromator(s), transmitter, scatterer, a velocity-controlling instrument (Mössbauer transducer), and a
timing detector. A schematic diagram is shown in Fig. 2.3. First, SR from a beamline
undulator passes through a pair monochromator Si crystal. The normal beamline
monochromator usually determines the energy of SR with the bandwidth of some
electron volts. This energy width is much wider than the hyperfine structure to analyze
in the transmitter or scatterer in the figure. The energy modulation by the hyperfine
structure is typically below some 10
−6 eV. Thus, the energy profile of SR from the
monochromator is virtually white, as shown in Fig. 2.3b. After the monochromator,
the SR penetrates the transmitter in Fig. 2.3a. A sample under study or an energy
reference substance at SR-based Mössbauer spectra is positioned as the transmitter.
In fact, one of these two should be arranged as the transmitter, and the other should
be as the scatterer. The difference between them is described later in this section.
Fig. 2.3 A schematic diagram of the instrumentation and mechanism of SR-based Mössbauer spectroscopy. a The arrangement of instruments. b The energy profile of SR from the monochromator;
c The profile of SR behind the transmitter, which has a resonant energy E; d The profile of the
scattering from the scatterer, which has a resonant energy E s controlled by the velocity transducer
in the case of E s = E t in the upper panel and E s = E t in the lower panel; e The detected intensity
dependence on the scatterer’s velocity. At the velocity v t , E s = E t is satisfied