Effect of tin concentration on mass independent isotopic fractionation in solvent extraction reaction using crown ether

Abstract

Isotopic anomalies have been reported for various elements in meteorites, and one factor is non-mass-dependent isotope fractionation (MIF) due to nuclear volume effects. This isotope effect is attributed to the fact that isotopes with smaller nuclear volumes have higher nuclear charge densities. The higher the nuclear charge density, the lower the Coulomb potential of the s-orbital electrons, which have a probability of existing in the nucleus, and thus stabilize it. This causes a bias of isotopes with small nuclear volumes toward molecules with small valence and shielding effects on s-orbital electrons that have electrons in the outermost s orbitals. On the other hand, clarifying the conditions under which nuclear volume effects occur is important for understanding isotopic anomalies in meteorites. In previous studies, MIF has been reported in solvent extraction experiments of Sr using crown ether, and the effect of hydration has been discussed because it becomes more pronounced at Sr concentrations above 2 M. In this study, we focus on Sn(II), which has electrons in the outermost s orbitals, and investigate the effect of Sn concentration on MIF.