Synchrotron radiation 57Fe-Mössbauer spectroscopy using nuclear monochromator

Abstract

A synchrotron radiation (SR) Mössbauer spectrometer has been developed by using a nuclear Bragg monochromator (NBM). It enables energy-domain 57 Fe SR-Mössbauer spectroscopy (SRMS). Doppler-shifted SR-Mössbauer radiation is produced by pure nuclear Bragg reflection (PNBR) from an oscillating 57 FeBO 3 crystal near the Néel point. In this paper, we describe the optics and its applications, including high-pressure SRMS, grazing incidence SRMS and γ -ray diffraction studies with the Rayleigh scattering of Mössbauer radiation (RSMR) method.

Reflectivity spectra as absorption resonant spectra: is it correct?

“…Therefore, this expression justifies the attempts to interpret the R-spectra in the total reflection region as the absorption resonant spectra and vindicates the use of the common software for Mo ¨ssbauer spectrum fitting (mentioned in Section 1), as done by e.g. Mitsui et al (2012aMitsui et al ( , 2016Mitsui et al ( , 2020, Cini et al (2018Cini et al ( , 2020, Cucinotta et al (2020), Okabayashi et al (2021a,b) and Yokota et al (2021). However, several effects can disturb the simplest linear connection between the reflectivity and absorption for angles in the total reflection region given by expression (5).…”

“…In several papers, R-spectra were measured from ultrathin resonant layers (see e.g. Mitsui et al, 2012aMitsui et al, ,b, 2020Ro ¨hlsberger et al, 2012;Haber et al, 2017;Cini et al, 2018Cini et al, , 2020Okabayashi et al, 2021a). It has been shown that the reflectivity amplitude from an ultrathin resonant layer placed under a reflecting medium R tot ð!Þ can be described by the formula (Andreeva & Lindgren, 2002;Andreeva et al, 2019)…”

“…In many cases, e.g. for investigations of thin resonant layers or surfaces, the Mo ¨ssbauer or X-ray resonant spectra near the absorption edges are measured in reflection geometry at small grazing angles, or some larger glancing angles in the case of the soft X-ray region (Martens & Rabe, 1980;Greaves, 1990;Waki & Hirai, 1989;Andreeva et al, 1991Andreeva et al, , 2018Irkaev et al, 1993a;Isaenko et al, 1994;Kao et al, 1994;Filatova et al, 1995Filatova et al, , 2006Sacchi & Mirone, 1998;Neumann et al, 1998;Se `ve et al, 1999;Oppeneer et al, 2003;Bergmann et al, 2006;Goering et ISSN 1600-5767 al., 2010Smekhova et al, 2010;Domashevskaya et al, 2011;Mitsui et al, 2012aMitsui et al, , 2016Mitsui et al, , 2020Ro ¨hlsberger et al, 2012;Holldack et al, 2014;Haber et al, 2016Haber et al, , 2017Cini et al, 2018Cini et al, , 2020Majhi et al, 2018;Cucinotta et al, 2020;Engel et al, 2020;Okabayashi et al, 2021a;Yokota et al, 2021;Ogawa et al, 2022). These experiments were carried out at synchrotron stations, which supply investigators with angular collimated and energy-selective radiation.…”

“…Therefore, for analysis of the Mo ¨ssbauer spectra, many authors (see e.g. Mitsui et al, 2012aMitsui et al, , 2016Mitsui et al, , 2020Cini et al, 2018Cini et al, , 2020Cucinotta et al, 2020;Yokota et al, 2021;Okabayashi et al, 2021a,b;Ogawa et al, 2022) have interpreted the R-spectra measured at grazing angles in the total reflection region as a simple sum of the resonant absorption lines (absorption is proportional to the imaginary part of the refraction index n ¼ 1 þ =2 or susceptibility ) and applied the software developed for absorption spectrum fitting like MossA, UNIVEM-MS and MossWinn, CONFIT2000, and SpectrRelax. However, no mathematical support for this simplified R-spectrum treatment has been developed for the reflectivity calculation in the region of total external reflection.…”

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

“…Its outstanding potential has been demonstrated by a grazing-incidence Mö ssbauer study of an iron thin film. As a special advantage the measurement is possible even in multi-bunch mode of SR. We believe that the developed spectrometer provides new possibilities for the application of polarized 57 Fe-SR-Mö ssbauer spectroscopy, including Mö ssbauer polarimeter (Pfannes & Gonser, 1974), -ray diffraction (Belyakov, 1975), ultrahigh-pressure experiments (Nasu, 1994), small-angle scattering (Shvyd'ko et al, 1996) and Rayleigh scattering of 57 Fe-SR-Mö ssbauer radiation (Masuda et al, 2008;Mitsui et al, 2012b).…”