Mossbauer Spectroscopy of Tin Compounds.

Arua, Awa Eke (1985)

Thesis

The Mossbauer spectrometer has been used in the transmission geometry to measure the isomer shifts and quadrupole splitting of tin and some of its inorganic compounds. The spectrometer has a Moire interferometer for absolute velocity calibration and the velocity data are fitted to a polynomial by the method of least squares. As a check on the velocity calibration, a natural iron foil absorber has been used. The ratio of the g-factors extracted from the iron data is in agreement with published values. The Mossbauer spectral data has been fitted with a sum of Lorentzians and the isomer shift and quadrupole splitting values obtained from these fits are in good agreement with published ones. Using s-electron densities Calculated from relativistic Hartree-Fock method for the various oxidation states of tin the fractional change in nuclear charge radius ΔR/R following a gamma transition has been calculated as (+2.05 ± 0.17) x 10-4. This is in good agreement with published values. From molecular orbital calculations, a configuration of 5s1..25p 2..8 has been suggested for α-tin. No equivalent data exists for β-tin. However, since the isomer shift is directly proportional to the s-electron density at the nuclear site, the measured isomer shift value has been used to suggest a configuration of 5s1.42 5p2.8 for β-tin. This is consistent with the saner shift values for the two allotropes of tin.

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