Calculations of Reduced Partition Function Ratios of Monomeric and Dimeric Boric Acids and Borates by the<i>ab initio</i>Molecular Orbital Theory

Oi, Takao

doi:10.1080/18811248.2000.9714880

Cited by 51 publications

(41 citation statements)

References 20 publications

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“…$1.030 and a (B32B4) ¼ 1.027 at 300 K, respectively (Zeebe 2005a;Liu & Tossell 2005). These results were based on various theoretical, analytical methods and on numerical approaches using ab initio molecular orbital theory and point towards a larger value for a (B32B4) , as also indicated by Oi (2000). Thus, theory predicts a value for the boron isotope fractionation factor between B(OH) 3 and B(OH) 4 2 at 258C of about 30‰ rather than 20‰.…”

Section: Inorganic Isotope Fractionationmentioning

confidence: 74%

Vital effects and beyond: a modelling perspective on developing palaeoceanographical proxy relationships in foraminifera

Zeebe

Biȷma

Hönisch

et al. 2008

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This paper mainly reviews our recent work on the biology and geochemistry of foraminifera with respect to their use as palaeoceanographic proxies. Our approach to proxy validation and development is described, primarily from a modeler's point of view. The approach is based on complementary steps in understanding the inorganic chemistry, inorganic isotope fractionation, and biological controls that determine palaeo-tracer signals in organisms used in climate reconstructions. Integration of laboratory experiments, field and culture studies, theoretical considerations and numerical modelling holds the key to the method's success. We describe effects of life-processes in foraminifera on stable carbon, oxygen, and boron isotopes as well as Mg incorporation into foraminiferal calcite shells. Stable boron isotopes will be used to illustrate our approach. We show that a mechanism-based understanding is often required before primary climate signals can be extracted from the geologic record because the signals can be heavily overprinted by secondary, non-climate related phenomena. Moreover, for some of the proxies, fundamental knowledge on the thermodynamic, inorganic basis is still lacking. One example is stable boron isotopes, a palaeo-pH proxy, for which the boron isotope fractionation between the dissolved boron compounds in seawater was not precisely known until recently. Attempts to overcome such hurdles are described and implications of our work for palaeoceanographic reconstructions are discussed.

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Section: Inorganic Isotope Fractionationmentioning

confidence: 74%

Vital effects and beyond: a modelling perspective on developing palaeoceanographical proxy relationships in foraminifera

Zeebe

Biȷma

Hönisch

et al. 2008

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“…Calculations were made at the B3LYP/6-31G(d) level of theory using the Gaussian 03 and 98 program packages (Gaussian Inc.) [17]. In our previous paper on boron (B) isotope fractionations between the boric acid (B(OH) 3 ) molecule and the monoborate anion (B(OH) 4 7 ) [18], we showed that a more advanced MO theory with a higher basis level basis set did not necessarily yield better rpfr results. The B3LYP theory is probably the most commonly used one in computational chemistry nowadays, and the 6-31G(d) basis set, although not a large one, may be one of the most standard basis sets.…”

Section: Analysesmentioning

confidence: 99%

Calcium isotope fractionation in liquid chromatography with crown ether resins

Nemoto

Suga

Fukuda

et al. 2012

Journal of Nuclear Science and Technology

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Breakthrough mode liquid chromatography was employed to study calcium isotope fractionation. Highly porous silica beads, the inner pores of which were embedded with a benzo-18-crown-6 ether resin or a benzo-15-crown-5 ether resin, were used as column packing material. For both the resins, enrichment of heavier isotopes of calcium was observed in the frontal part of their respective calcium chromatograms. The values of the isotope fractionation coefficient were on the order of 10 73 and 10 74for the benzo-18-crown-6 ether and benzo-15-crown-5 ether resins, respectively. The observed isotope fractionation coefficient was dependent on the concentration of hydrochloric acid in the calcium feed solution; a higher hydrochloric acid concentration resulted in a smaller fractionation coefficient value. The present calcium isotope effects were most probably mass dependent, indicating they came from isotope effects based on molecular vibration. Molecular orbital calculations supported the present experimental results in a qualitative fashion.

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“…The calculated values reported late, however, are 0.975 [13,14] , 0.974 [15,16] and 0.972 [17] , which are distinctly lower than 0.981.…”

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confidence: 56%

“…Various theoretical α 4-3 values of 0.981 [12] , 0.975 [13,14] , 0.974 [15,16] and 0.972 [17] have been proposed. Zeebe [18] concluded that theoretical α 4-3 values may vary between 0.980 and 0.952 at 300 K.…”

Section: A Practical Model For the Reconstruction Of Paleo-ph Of Seawmentioning

confidence: 98%

Boron isotopic fractionation in laboratory inorganic carbonate precipitation: evidence for the incorporation of B(OH)3 into carbonate

Liu

Wang

et al. 2008

Sci. China Ser. D-Earth Sci.

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A laboratory inorganic carbonate precipitation experiment at high pH of 8.96 to 9.34 was conducted, and the boron isotopic fractionations of the precipitated carbonate were measured. The data show that boron isotopic fractionation factors (α carb-3 ) between carbonate and B(OH) 3 in seawater range 0.937 and 0.965, with an average value of 0.953. Our results together with those reported by Sanyal and collaborators show that the α carb-3 values between carbonate and B(OH) 3 in solution are not constant but are negatively correlated with the pH of seawater. The measured boron isotopic compositions of carbonate precipitation (δ 11 B carb ) do not exactly lie on the best-fit theoretical δ 11 B 4 -pH curves and neither do they exactly parallel any theoretical δ 11 B 4 -pH curves. Therefore, it is reasonable to argue that a changeable proportion of B(OH) 3 with pH of seawater should also be incorporated into carbonate except for the dominant incorporation of B(OH) 4 − in carbonate . Hence, in the reconstruction of the paleo-pH of seawater from boron isotopes in marine biogenic carbonates, the use of theoretical boron isotopic fractionation factor (α 4-3 ) between B(OH) 4 − and B(OH) 3 is not suitable. Instead, an empirical equation should be established. boron, isotopic fractionation, biogenic carbonate, B(OH) 3 incorporation Naturally occurring boron has two stable isotopes, 11 B and 10 B, which have average relative abundances of 80.17% and 19.83%, respectively. Boron is dissolvable element and can participate widely in various chemical, physical and geological processes. The isotopic fractionation occurs in these processes. Briefly, there are two dominant species of dissolved boron, B(OH) 3 and B(OH) 4 -, in solution and their relative concentrations are controlled by pH as following relation: B(OH) 3 (B 3 )+ H 2 O→ B(OH) 4 − (B 4 )+ H + (1) Boron has no variety of valences and isotopic fractionation of boron takes place between B 3 and B 4 − , which have different reduced partition function ratios. The light isotope 10 B is enriched in B(OH) 4 − compared to B(OH) 3 [1-3]. The characteristic of boron isotopic fractionation has been proverbially applied in crust-mantle evolution and subduction-related processes, sedimentary environments

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Calculations of Reduced Partition Function Ratios of Monomeric and Dimeric Boric Acids and Borates by theab initioMolecular Orbital Theory

Cited by 51 publications

References 20 publications

Vital effects and beyond: a modelling perspective on developing palaeoceanographical proxy relationships in foraminifera

Vital effects and beyond: a modelling perspective on developing palaeoceanographical proxy relationships in foraminifera

Calcium isotope fractionation in liquid chromatography with crown ether resins

Boron isotopic fractionation in laboratory inorganic carbonate precipitation: evidence for the incorporation of B(OH)3 into carbonate

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