Determination of tin equilibrium isotope fractionation factors from synchrotron radiation experiments

A method of determination of the reduced isotopic partition function ratio (beta-factor) from the partial density of state (PDOS) obtained by inelastic nuclear resonant X-ray scattering (INRXS) in synchrotron radiation experiments has been established. The method has been demonstrated by the example of tin isotopes. The tin beta-factors for CaSnO3, SnO2, SnO have been computed from the INRXS-derived PDOSs. ln beta(122/116Sn) =(0.390 +/- 0.0076)x - (0.00160 +/- 0.0000242)x(2) + (1.099 +/- 0.0573) - 10(-5)x(3)) for SnO ln(beta 122/116Sn) = (0.771 +/- 0.0150)x - (0.00392 +/- 0.000061)x(2) + (3.548 +/- 0.287). 10(-5)x(3) for SnO2 ln beta(122/116Sn) = (0.776 +/- 0.0157)x - (0.00334 +/- 0.000064)x(2) + (2.561 +/- 0.157). 10(-5)x(3) for CaSnO3 Equilibrium Sn-122/116 isotope fractionation between di- and tetravalent tin compounds is about 0.4 parts per thousand at 1000 K and about 4.1 parts per thousand at room temperature and can be measured by modern multicollector inductively-coupled plasma mass-spectrometers. Tin beta-factors reveal dependence on oxidation state previously detected for iron isotopes. A comparison of the tin beta-factors for SnO2 obtained on the basis of the INRXS-derived PDOS with those obtained by the Mossbauer spectroscopy method shows that both methods give similar results, but application of synchrotron radiation provides more accurate and reliable data. Equilibrium stable isotope fractionation of transition metals between different oxidation state compounds is not negligible even for elements as heavy as tin. Copyright (c) 2005 Elsevier Ltd.