Raman study of ferric nitrate crystalline hydrate and variably hydrated liquids
01 Sep 1974-Journal of Chemical Physics (American Institute of Physics)-Vol. 61, Iss: 5, pp 1748-1754
TL;DR: A Raman investigation on crystalline ferric nitrate enneahydrate (FNEH) has shown that NO3− and Fe(H2O)63+ ions are present in two distinct environments in the monoclinic unit cell of the crystal as mentioned in this paper.
Abstract: A Raman investigation on crystalline ferric nitrate enneahydrate (FNEH) has shown that NO3− and Fe(H2O)63+ ions are present in two distinct environments in the monoclinic unit cell of the crystal. In FNEH melt, it has been found that NO3− and Fe3+ ions form a complex in which water is also coordinated to the Fe3+ ion. Raman evidence is presented which indicates that NO3− ion in the nitrate complex is coordinated to the Fe3+ ion in monodentate fashion, with an appreciable covalency in the Fe3+–ONO2− bond. The addition of water to FNEH melt causes dissociation of the nitrate complex. This complex almost ceases to exist when the water content of the melt is raised to 28 mole of water per mole of the salt. A weak polarized band at ∼407 cm−1 in the Fe(NO3)3 · xH2O system (x ≥ 28) has been attributed to the presence of the hydrolysis product of Fe3+ ions. The effect of dilution and of temperature on this band has also been investigated. It is suggested that the hydrolysis product of the salt exists in the form ...
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TL;DR: In this paper, Kuharski et al. computed the nuclear tunneling enhancement of the rate for ferrous-ferric exchange in water and showed that the quantum dynamics of water molecules beyond the first solvation shell prove quite significant.
Abstract: By computer simulation and also by analytical methods we have computed the nuclear tunneling enhancement of the rate for ferrous–ferric exchange in water. The model we have examined is the one studied earlier where we treated water as a classical liquid [R. A. Kuharski, J. S. Bader, D. Chandler, M. Sprik, M. L. Klein, and R. W. Impey, J. Chem. Phys. 89, 3248 (1988)]. But now we treat water quantum mechanically and find that the tunneling enhancement is a factor of 60 in the rate constant. Further, as observed experimentally, we find that the isotope shift on the rate when changing from D2O to H2O is approximately a factor of 2. The computer simulation aspects of these calculations employ path integral methods and a novel partitioning of the free energy associated with electron transfer. Our results show that it is insufficient to quantize only the atoms composing the ligands. The quantum dynamics of water molecules beyond the first solvation shell prove quite significant.
253 citations
TL;DR: In this paper, the authors have simulated the solvent relaxation immediately after photoinduced electron transfer of an aqueous ferric-ferrous system and showed that the process occurs in a sub-picosecond time scale.
178 citations
TL;DR: In this paper, Ab initio molecular orbital pair potentials for the interaction of Fe2+ and Fe3+ ions with H2O were used to calculate the three-body energies from the interactions of two water molecules with the cations.
Abstract: Ab initio molecular orbital pair potentials for the interaction of Fe2+ and Fe3+ ions with H2O are reported. Molecular dynamics calculations of the static structure of the solvation shell of Fe2+ and Fe3+ in water using the ab initio pair potentials gives physically incorrect results, i.e., the coordination numbers are eight instead of six as observed experimentally. This problem has also been encountered by other workers for divalent transition metal ions in water. By computing three‐body energies from the interaction of two water molecules with the cations, we show that the origin of the problem is most likely in the assumption of the additivity of the pair potentials, i.e., neglect of many‐body forces. Empirical potentials are reported which take approximate account of the three‐body forces and give coordination numbers of six for both Fe2+ and Fe3+ in water.
143 citations
TL;DR: The Raman technique can unambiguously identify ferrous sulfate of various hydration states and jarosites bearing different alkali metal ions.
50 citations
TL;DR: In this article, Fe promoted NOx storage materials were synthesized in the form of FeOx/BaO/Al2O3 ternary oxides with varying BaO (8 and 20 wt %) and Fe (5 and 10 wt percent) contents.
Abstract: Fe promoted NOx storage materials were synthesized in the form of FeOx/BaO/Al2O3 ternary oxides with varying BaO (8 and 20 wt %) and Fe (5 and 10 wt %) contents. Synthesized NOx storage materials were investigated via TEM, EELS, BET, FTIR, TPD, XRD, XPS, and Raman spectroscopy, and the results were compared with the conventional BaO/Al2O3 NOx storage system. Our results suggest that the introduction of Fe in the BaO/Al2O3 system leads to the formation of additional NOx storage sites which store NOx mostly in the form of bidentate nitrates. NO2 adsorption experiments at 323 K via FTIR indicate that, particularly in the early stages of the NOx uptake, the NOx storage mechanism is significantly altered in the presence of Fe sites where a set of new surface nitrosyl and nitrite groups were detected on the Fe sites and the surface oxidation of nitrites to nitrates is significantly hindered with respect to the BaO/Al2O3 system. Evidence for the existence of both Fe3+ as well as reduced Fe2+/(3−x)+ sites on the ...
32 citations
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248 citations
TL;DR: In this article, the infrared spectra from 300-880 cm−1 of 208 inorganic substances are reported, nearly all of which are salts containing polyatomic ions, and a list of characteristic frequencies is given for twenty ions.
189 citations