Best Practices and Protocols in Mössbauer Spectroscopy

Abstract

Over the past 50 years or so, the authors have written and reviewed many papers dealing with Mossbauer spectral research and have noticed many pitfalls, omissions, and marginal to poor practices in the literature. This paper first describes the best recommended practices and protocols for measuring, analyzing, and presenting Mossbauer spectra for publication. To illustrate these recommendations, the paper next presents a discussion of the techniques that ensure the best possible Mossbauer-effect spectrometer calibration, the best methods for minimizing the spectral line widths and thus obtaining the best possible spectral resolution, and the best spectral velocity ranges to use. A variety of iron containing compounds chosen from the fields of inorganic, organic, and material chemistry are used to illustrate the best practices and protocols that should be used. These materials include an organoiron carbonyl complex, iron phosphate compounds, two single molecule magnet compounds, and iron spin-state crossover complexes.

Comment on “Engineering Shape Anisotropy of Fe3O4-γ-Fe2O3 Hollow Nanoparticles for Magnetic Hyperthermia”

“…Hence, attempting to fit a two-sextet model for maghemite in these spectra is not acceptable for all practical purposes. Furthermore, the information on the line width is vital, especially for the sample NRs, because it can throw light on the requirement of fitting an additional sextet corresponding to hematite, which the authors fail to report in Table S4. We would further like to mention that they have not included the relative transmission values in Figure 4, a standard practice while presenting the Mössbauer spectroscopic outcome. , …”

“…We would further like to mention that they have not included the relative transmission values in Figure 4, a standard practice while presenting the Mossbauer spectroscopic outcome. 15,25 ■ CONCLUSION Hence, the fit routine should include three sextets for the spectrum obtained for the NR samples corresponding to two sextets representing magnetite and a sextet for maghemite contributions. An additional sextet may be considered (for hematite) after careful scrutinization of the values of the obtained line-width and hyperfine parameters.…”

Synthesis, Physicochemical Characterization, and Catalytic Evaluation of Fe3+-Containing SSZ-70 Zeolite

“…All of the initial spectral fit parameters for the 5 K as-made Fe-SSZ-70 spectrum are consistent with high-spin Fe 3+ ions in a predominately four-coordinate pseudo-tetrahedral coordination environment. 37,45 In contrast, all of the initial spectral fit parameters and the changes between 290 and 5 K for the calcined Fe-SSZ-70 spectra are fully consistent with high-spin Fe 3+ ions in a predominately six-coordinate pseudo-octahedral coordination environment. Indeed, calcining the as-made Fe-SSZ-70 sample has a substantial influence on the local Fe 3+ coordination environments, with a shift from a four-coordinate pseudo-tetrahedral environment to a predominantly pseudooctahedral environment.…”

“…All isomer shifts are reported relative to α-iron at 290 K. The thickness of the Mossbauer spectral absorbers was about 50 mg/cm 2 of the sample as a fine powder. 37 Electron paramagnetic resonance (EPR) spectra were measured on a Varian E-12 spectrometer. The field sweep and signal average were controlled by the EWWin software and hardware package.…”

“…The spectrometer was calibrated at 290 K with a 30 μm α-iron foil. All isomer shifts are reported relative to α-iron at 290 K. The thickness of the Mössbauer spectral absorbers was about 50 mg/cm 2 of the sample as a fine powder …”