Influences of nuclear size and shape and nuclear spin on chemical isotope effect of zirconium‐crown complex

Fujii, Toshiyuki; Yamamoto, Tadashi; Inagawa, Jun; Watanabe, Kazuo; Nishizawa, Kazushige

doi:10.1002/bbpc.19981020410

Cited by 18 publications

(9 citation statements)

References 30 publications

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“…Anomalous (non‐mass‐dependent) isotope effects may also arise from symmetry effects [e.g., Gellene , 1996] or changes of other nuclear properties upon isotopic substitution (such as nuclear spin, size or shape). The latter changes can cause isotope shifts in the electronic spectra as well as vibrational and rotational energy levels [ Bigeleisen , 1996; Fujii et al , 1998; Tiemann et al , 1982]. Moreover, stellar nucleosynthesis, radioactive decay or natural nuclear reactors (such as in Oklo, Gabon) may cause exceptional isotopic variations even in environments uninfluenced by mankind.…”

Section: Terminologymentioning

confidence: 99%

Contribution of mass‐dependent fractionation to the oxygen isotope anomaly of atmospheric nitrous oxide

2004

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[1] Similar to other oxygen-bearing atmospheric compounds, lower-stratospheric and tropospheric nitrous oxide (N 2 O) show an oxygen isotope anomaly. This anomaly can be explained by in situ atmospheric chemical sources that transfer the well-known oxygen isotope anomaly of ozone to N 2 O. The isotope anomaly of ozone, in turn, is caused by non-mass-dependent fractionation during its formation. Nevertheless, recent work claimed that photodissociation of stratospheric N 2 O could account for up to half of the observed anomaly in N 2 O without having to invoke chemical N 2 O sources. It is shown that this prediction is due to the choice of inadequate parameters in the specific underlying physicochemical model of isotopic fractionation in N 2 O photolysis. Budget calculations based on experimentally measured fractionation factors at stratospherically relevant wavelengths show only negligible contributions of N 2 O photolysis to the observed oxygen isotope anomaly. However, biological sources at the Earth's surface, which are usually considered to produce mass-dependently fractionated N 2 O, may actually be responsible for part of the observed anomaly. This is as a consequence of slight variations in the massdependent relationships between 17 O and 18 O isotope effects and the relationship assumed in the definition of the oxygen isotope anomaly. Up to 44% of the observed anomaly might be explained by this ''numerical source'' that was not recognized previously. As a prerequisite to understand this possibly surprising result, the existing definitions of isotope anomalies and their practical consequences are analyzed. An accurate terminology will also benefit future generations of researchers in the rapidly growing fields of atmospheric isotope chemistry and physics.

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Section: Terminologymentioning

confidence: 99%

Contribution of mass‐dependent fractionation to the oxygen isotope anomaly of atmospheric nitrous oxide

2004

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“…Toshiyuki Fujii and his co-workers have made tremendous efforts on experimental evaluations of NVEs for isotope systems, including Ti, Sn, Zr, Ni, Zn, Gd, Nd, Cr, Sr, Te and Cd etc. 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 Meanwhile, they performed quantum chemistry calculations for a few isotope systems, such as Zn 20 21 , Ni 18 , Tl 30 and Pb 31 . Schauble 4 used quantum chemistry methods to calculate NVEs of some heavy elements (e.g., Hg, Tl) and showed that the NVE could affect isotope fractionations of heavy elements to surprising degrees.…”

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confidence: 99%

Nuclear volume effects in equilibrium stable isotope fractionations of mercury, thallium and lead

Yang

Liu

2015

Sci Rep

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The nuclear volume effects (NVEs) of Hg, Tl and Pb isotope systems are investigated with careful evaluation on quantum relativistic effects via the Dirac’s formalism of full-electron wave function. Equilibrium 202Hg/198Hg, 205Tl/203Tl, 207Pb/206Pb and 208Pb/206Pb isotope fractionations are found can be up to 3.61‰, 2.54‰, 1.48‰ and 3.72‰ at room temperature, respectively, larger than fractionations predicted by classical mass-dependent isotope fractionations theory. Moreover, the NVE can cause mass-independent fractionations (MIF) for odd-mass isotopes and even-mass isotopes. The plot of vs. for Hg-bearing species falls into a straight line with the slope of 1.66, which is close to previous experimental results. For the first time, Pb4+-bearing species are found can enrich heavier Pb isotopes than Pb2+-bearing species to a surprising extent, e.g., the enrichment can be up to 4.34‰ in terms of 208Pb/206Pb at room temperature, due to their NVEs are in opposite directions. In contrast, fractionations among Pb2+-bearing species are trivial. Therefore, the large Pb fractionation changes provide a potential new tracer for redox conditions in young and closed geologic systems. The magnitudes of NVE-driven even-mass MIFs of Pb isotopes (i.e., ) and odd-mass MIFs (i.e., ) are almost the same but with opposite signs.

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“…6 Most of these works represent the study of the reaction of an element with dicyclohexano-18crown-6 (DC18C6) crown ether. [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] Metal/metalloid was dissolved in aqueous solutions of HCl with different acid concentrations. Different species are predominant in these solutions depending on the HCl concentration.…”

Section: Discussionmentioning

confidence: 99%

Magnetic isotope effect and theory of atomic orbital hybridization to predict a mechanism of chemical exchange reactions

Epov

2011

Phys. Chem. Chem. Phys.

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A novel approach is suggested to investigate the mechanisms of chemical complexation reactions based on the results of Fujii with co-workers; they have experimentally observed that several metals and metalloids demonstrate mass-independent isotope fractionation during the reactions with the DC18C6 crown ether using solvent-solvent extraction. In this manuscript, the isotope fractionation caused by the magnetic isotope effect is used to understand the mechanisms of chemical exchange reactions. Due to the rule that reactions are allowed for certain electron spin states, and forbidden for others, magnetic isotopes show chemical anomalies during these reactions. Mass-independent fractionation is suggested to take place due to the hyperfine interaction of the nuclear spin with the electron spin of the intermediate product. Moreover, the sign of the mass-independent fractionation is found to be dependent on the element and its species, which is also explained by the magnetic isotope effect. For example, highly negative mass-independent isotope fractionation of magnetic isotopes was observed for reactions of DC18C6 with SnCl(2) species and with several Ru(III) chloro-species, and highly positive for reactions of this ether with TeCl(6)(2-), and with several Cd(II) and Pd(II) species. The atomic radius of an element is also a critical parameter for the reaction with crown ether, particularly the element ions with [Kr]4d(n)5s(m) electron shell fits the best with the DC18C6 crown ring. It is demonstrated that the magnetic isotope effect in combination with the theory of orbital hybridization can help to understand the mechanism of complexation reactions. The suggested approach is also applied to explain previously published mass-independent fractionation of Hg isotopes in other types of chemical exchange reactions.

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Influences of nuclear size and shape and nuclear spin on chemical isotope effect of zirconium‐crown complex

Cited by 18 publications

References 30 publications

Contribution of mass‐dependent fractionation to the oxygen isotope anomaly of atmospheric nitrous oxide

Contribution of mass‐dependent fractionation to the oxygen isotope anomaly of atmospheric nitrous oxide

Nuclear volume effects in equilibrium stable isotope fractionations of mercury, thallium and lead

Magnetic isotope effect and theory of atomic orbital hybridization to predict a mechanism of chemical exchange reactions

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