⁵⁷Fe polarization-dependent synchrotron Mössbauer spectroscopy using a diamond phase plate and an iron borate nuclear Bragg monochromator

Energy-domain ⁵⁷Fe polarization-dependent synchrotron radiation Mössbauer spectroscopy was developed by using a diamond X-ray phase plate and an iron borate nuclear Bragg monochromator. The former controls the polarization of the incident synchrotron radiation X-rays and the latter filters the ⁵⁷Fe-Mössbauer radiation with a narrow bandwidth of ∼3.4 Γ₀ (Γ₀ ≃ 4.7 neV: natural linewidth of the ⁵⁷Fe nucleus) from the broadband synchrotron radiation. The developed nuclear diffraction optics allowed ⁵⁷Fe-Mössbauer studies to be performed with various polarization states, i.e. linear polarization, circular polarization and non-polarization. In this paper, the spectrometer system, beam characterization, performance-test experiments and a grazing-incidence Mössbauer measurement of an isotope-enriched (⁵⁷Fe: 95%) iron thin film are described.