: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Whenever a mineral or mineral assemblage comes into contact with a fluid with which it is out of equilibrium, reequilibration will tend to take place to reduce the free energy of the whole system (i.e., of the solid + fluid). Such fluid-solid interactions span a very wide range of possible reactions, and are responsible for most of the mineral assemblages we see in the Earth’s crust. However, before discussing mineral replacement reactions, we will put them into the broader context of fluid-solid interactions by considering some examples of such reequilibration.

In the simplest case, we could consider the situation where a mineral, thermodynamically stable under some speciflc temperature and pressure conditions, comes into contact with pure water, such as quartz within its stability field (e.g., at T = 100 °C and 1 atmosphere pressure). Clearly, quartz will tend to dissolve until, at equilibrium, the aqueous silica solution, which at neutral pH is H4SiO4(aq), becomes saturated with respect to quartz. The reaction for this equilibration can be written:

\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \[SiO\_{2\ (qtz)}\ +\ H\_{2}O\ {\leftrightarrow}\ H\_{4}SiO\_{4(aq)}\] \end{document}(1) 

The equilibrium solubility constant for reaction (1) is given by

\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \[\mathit{K}\_{\mathit{sp}}\ (\mathit{qtz})\ =\ \frac{\mathit{a}(H\_{4}SiO\_{4})\_{\mathit{aq}}}{\mathit{a}(SiO\_{2})\_{\mathit{qtz}}\ {\cdot}\ \mathit{a}(H\_{2}O)}\ =\ \mathit{a}(H\_{4}SiO\_{4})\_{\mathit{aq}}\] \end{document} 

where a ( i ) aq stands for the activity of the parenthetical aqueous species. For the case of pure quartz and pure water where the activity is 1, K sp ( qtz ) ~1.2 × 10−3 at 100 °C and 1 atmosphere pressure. However, if under these conditions the solid silica phase in contact with pure water was cristobalite (the high temperature polymorph of SiO2), the resulting aqueous solution, saturated with respect to cristobalite, would be supersaturated with respect to quartz, since the less stable phase is more soluble. The value of K sp for cristobalite at 100 °C and 1 atmosphere pressure is ~5.1 × 10−3. Thus the thermodynamics would indicate that quartz …

Mineral Replacement Reactions

Hierarchical NiMoO4 architectures assembled from well-aligned uniform nanosheets or nanorods are successfully grown on various conductive substrates using a facile and effective general approach. Importantly, the nanostructures of NiMoO4 can be easily controlled to be nanosheets or nanorods by using different solvents. By virtue of their intriguing structure features, NiMoO4 nanosheets as integrated additive-free electrodes for supercapacitors manifest higher Faradaic capacitance than NiMoO4 nanorods. Moreover, an asymmetric supercapacitor (ASC) is constructed using the as-prepared NiMoO4 nanosheets as the positive electrode and activated carbon (AC) as the negative electrode. The optimized ASC with an extended operating voltage range of 0–1.7 V displays excellent electrochemical performance with a high energy density of 60.9 Wh kg−1 at a power density of 850 W kg−1 in addition to superior rate capability. Furthermore, the NiMoO4//AC ASC device exhibits remarkable cycling stability with 85.7% specific capacitance retention after 10 000 cycles. The results show that these NiMoO4-based nanostructures are promising for high-energy supercapacitors.

Controlled Growth of NiMoO4 Nanosheet and Nanorod Arrays on Various Conductive Substrates as Advanced Electrodes for Asymmetric Supercapacitors

Infrared and raman spectra of moo3 molybdenum trioxides and moo3.xh2o molybdenum trioxide hydrates

The mechanism of reequilibration of solids in the presence of a fluid phase

Longitudinal-transverse splitting effects in IR absorption spectra of MoO3

Hydrogen molybdenum bronzes, HxMoO3, of Type-I (x=0.21), Type-III (x=1.55), and Type-IV (x=1.90) were prepared by the Glemser’s method. Type-II (x=0.91) was obtained from Type-III by standing in air for 120 days. The bronzes with low hydrogen contents were stable, but those with high contents were not so stable. All these bronzes have been studied by X-ray diffraction, IR spectroscopy, and TG-DTA. Bronzes with high hydrogen contents were changed upon heating in air, successively, to those with low hydrogen contents by the evolution of H2.

Preparation and Characterization of Hydrogen Molybdenum Bronzes, HxMoO3

Crystal structure of cobalt molybdate hydrate CoMoO4·nH2O

Ligand Effects of 2-(2-Pyridyl)benzazole−Pd Complexes on the X-ray Crystallographic Structures, 1H NMR Spectra, and Catalytic Activities in Mizoroki−Heck Reactions

Kazuo Eda

Papers

Longitudinal-transverse splitting effects in IR absorption spectra of MoO3

Preparation and Characterization of Hydrogen Molybdenum Bronzes, HxMoO3

Crystal structure of cobalt molybdate hydrate CoMoO4·nH2O

Ligand Effects of 2-(2-Pyridyl)benzazole−Pd Complexes on the X-ray Crystallographic Structures, 1H NMR Spectra, and Catalytic Activities in Mizoroki−Heck Reactions

Synthesis, crystal structure, and structural conversion of Ni molybdate hydrate NiMoO4·nH2O