E. V. Petrova

Mossbauer spectroscopy with high velocity resolution in the study of iron-bearing minerals in meteorites

Application of Mossbauer spectroscopy with a higher velocity resolution than commonly applied appeared to be useful for obtaining hyperfine parameters of 57 Fe nuclei with a lower experimental error and for a better fit of complicated spectra. The study of iron-bearing phases in ordinary and carbonaceous chondrites as well as iron meteorite and extracted iron-nickel phosphides by Mossbauer spectroscopy with an improved velocity resolution (measurement in 4096 channels, presentation in 1024 channels) demonstrated new results which had not been obtained from Mossbauer spectra measured in 512 channels or less. In particular, it was possible to reveal spectral components related to M1 and M2 sites in olivine and pyroxene in Mossbauer spectra of bulk samples of ordinary chondrites and then to evaluate the temperatures of equilibrium cation distribution. Moreover, differences in small variations of Mossbauer hyperfine parameters were obtained for 57 Fe in M1 and M2 sites for both olivine and pyroxene.

Comparison of iron-bearing minerals in ordinary chondrites from H, L and LL groups using Mössbauer spectroscopy with a high velocity resolution.

Ordinary chondrites from H, L and LL groups were studied using Mössbauer spectroscopy with a high velocity resolution. Mössbauer parameters of spectral components were obtained using new fitting model excluding the effect of previous misfits of troilite component. Obtained parameters were related to corresponding iron-bearing minerals in ordinary chondrites. The differences of these minerals content as well as small differences in the hyperfine parameters of the same iron-bearing minerals were revealed for different meteorites. The temperatures of equilibrium cations distribution in silicates were estimated and suitable parameters for classification of H, L and LL chondrites were supposed using Mössbauer parameters.

Study of Chelyabinsk LL5 meteorite fragment with a light lithology and its fusion crust using Mössbauer spectroscopy with a high velocity resolution

Study of Chelyabinsk LL5 ordinary chondrite fragment with a light lithology and its fusion crust, fallen on February 15, 2013, in Russian Federation, was carried out using Mossbauer spectroscopy with a high velocity resolution. The Mossbauer spectra of the internal matter and fusion crust were fitted and all components were related to iron-bearing phases such as olivine, pyroxene, troilite, Fe-Ni-Co alloy, and chromite in the internal matter and olivine, pyroxene, troilite, Fe-Ni-Co alloy, and magnesioferrite in the fusion crust. A comparison of the content of different phases in the internal matter and in the fusion crust of this fragment showed that ferric compounds resulted from olivine, pyroxene, and troilite combustion in the atmosphere.

Study of Meteorites Using Mössbauer Spectroscopy with High Velocity Resolution

Study of iron‐bearing phases in ordinary and carbonaceous chondrites as well as iron meteorite and extracted iron‐nickel phosphides by Mossbauer spectroscopy with improved velocity resolution (measurement in 4096 channels, presentation in 1024 channels) demonstrated new results which were not obtained from Mossbauer spectra measured in 512 channels or less. Fitting of the iron meteorite Mossbauer spectrum measured for the first time with presentation in 4096 channels showed new details probably related to the complicated phase composition.