[M-ZZ45] Frontiers in geochemistry: discussing its appeal and future prospects

[MZZ45-10] Mass-independent isotopic fractionation induced by the magnetic isotope effect and isotope geochemistry of heavy elements

★Invited Papers

*Yusuke Fukami¹ (1.Gakushuin University)

Keywords:mass-independent isotopic fractionation, magnetic isotope effect, nuclear spin, odd isotope

Magnetic isotope effect (MIE) is known as the isotope effect that fractionates isotopes with a nuclear spin from isotopes without a nuclear spin, resulting mass-independent isotope fractionation because the presence or absence of nuclear spins in isotopes causes difference in chemical reaction rates (Buchachenko, 1976; Turro, 1983). Most studies on high-precision isotope analysis of MIE for heavy elements have been conducted on mercury (e.g., Blum et al., 2014), which is used as an environmental tracer, and few studies have been performed on other heavy elements. Recently, the MIE for tin isotopes has been reported in meteorites (Bragagni et al., 2023), and the MIE has been reported as a cause of analytical artifact compromise high-precision tungsten isotope analysis (Budde et al., 2022). It will be increasingly important to expand our understanding for the nature of mass-independent fractionation induced by MIE for isotopes of heavy elements other than mercury. In heavy elements with even atomic numbers, such as mercury and tin, only odd isotopes have a nuclear spin. These heavy elements have multiple odd isotopes, enabling compare magnitude of fractionation induced by MIE among odd isotopes, and whether fractionation by the MIE causes comparable variations for different odd isotopes have been open issues. Recent studies for mercury reported the difference in the correlation between odd isotopes in fractionation induced by the MIE has been reported to vary with the reaction system (e.g. Tsui et al., 2020). Further, experimental study for tin isotopes by our group was consistent with theoretical prediction (Buchachenko, 2018) regarding to studies for mercury, suggesting that this prediction is applicable to other heavy elements. These studies indicate that mass-independent isotopic fractionation induced by the MIE has following features: (i) fractionation of odd isotopes from even isotopes, (ii) difference of magnitude of fractionation between odd isotopes controlled by nuclear magnetic moment of isotopes, (iii) correlation between odd isotopes in fractionation varies according to the condition of reaction system. In the presentation, we will review the mechanism and nature of mass-independent isotopic fractionation induced by the MIE, and discuss potential contribution of MIE to natural samples, such as isotope anomalies in meteorites.