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1.
Reduced TiO2(110) surfaces usually have OH groups as a result of H2O dissociation at oxygen vacancy defects. Because of excess electrons due to OH adsorption, OH/TiO2 exhibit interesting properties favorable to further O2 or H2O adsorption. Both O2 and H2O can adsorb and easily diffuse on the OH/TiO2 surface; such behavior plays a significant role in photocatalysis, heterogeneous catalysis, electronic devices and sensors. Indeed, the processes of H2O dissociation, O2 and H2O diffusion on such TiO2 surfaces, in the presence of OH groups, are important issues in their own right. Herein, the most recent experimental and theoretical progresses in understanding the interactions between adsorbed OH groups and O2, or H2O, over TiO2(110) surfaces and their implications will be reviewed. 相似文献
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Gustav Peinel Horst Frischleder Frieder Birnstock 《Theoretical chemistry accounts》1980,57(3):245-253
Starting from the molecular potential we get, by using elementary electrostatics, information about energetically favoured regions for interaction with ions and dipoles around H2O and H2CO. The molecule-dipole interaction is represented by the electric field patterns. 相似文献
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We use ab initio electronic structure methods to calculate the many-body decomposition of the binding energies of the OH.(H2O)n (n=2,3) complexes. We employ MP2 and CCSD(T) levels of theory with aug-cc-pVDZ and aug-cc-pVTZ basis sets and analyze the significance of the nonpairwise interactions between OH radical and the surrounding water molecules. We also evaluate the accuracy of our newly developed potential function, the modified Thole-type model, for predicting the many-body terms in these complexes. Our analysis of the many-body contributions to the OH.(H2O)n binding energies clearly shows that they are just as important in the OH interactions with water as they are for interactions in pure water systems. 相似文献
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The rate coefficient for the reaction has been determined in mixtures of nitric acid (HNO3) and argon in incident shock wave experiments. Quantitative OH time-histories were obtained by cw narrow-linewidth uv laser absorption of the R1(5) line of the A2 σ+ ← X2 Πi (0,0) transition at 32606.56 cm?1 (vacuum). The experiments were conducted over the temperature range 1050–2380 K and the pressure range 0.18–0.60 atm. The second-order rate coefficient was determined to be with overall uncertainties of +11%, ?16% at high temperatures and +25%, ?22% at low temperatures. By incorporating data from previous investigations in the temperature range 298–578 K, the following expression is determined for the temperature range 298–2380 K © 1994 John Wiley & Sons, Inc. 相似文献
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Quantum dynamics of the H + O2 --> O + OH reaction on an accurate ab initio potential energy surface
We report exact time-dependent and time-independent quantum mechanical studies of the title reaction on an accurate ab initio potential energy surface of Xu et al. (J. Chem. Phys. 2005, 122, 24305). The J = 0 reaction probabilities for several reactant states show sharp resonance structures superimposed on relatively low backgrounds, and they are remarkably different from existing quantum results on an earlier potential energy surface (DMBE-IV). The new findings reported here suggest that our current understanding of this important reaction might require significant revision. 相似文献
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A model potential for the adsorbate-adsorbate interaction among OH and H2O molecules adsorbed on a Pt(111) surface has been developed solely based on first-principle calculations. By combining this directional-dependent model potential for the lateral interaction with a lattice model of Ising type, large length scale structure calculations can be made. The strength of different hydrogen bonds can be analyzed in detail from this model potential. It is found that the hydrogen bond between OH and H2O molecules is stronger than that between two H2O molecules (0.4 eV per pair as compared to 0.2 eV per pair, respectively). Via the computed chemical potential for water in mixed OH + H2O overlayers the water uptake as a function of oxygen precoverage on Pt(111) has been determined. The results compare very well with recent experiments. 相似文献
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Neutral ZnO and ZnOH molecules could be produced in a molecular beam by expansion of laser ablated zinc together with H2O, O2 or N2O seeded in a rare gas (Ar, Ne, He). Due to the characteristic Zn isotope distribution, the zinc containing compounds, ionized with a 100 fs laser pulse, could unambiguously be identified with a TOF mass spectrometer. The abundance of ZnOH produced in our experiments exceeds the one of ZnO and ZnN by orders of magnitude if H2O is present in the system. Small quantities of (ZnO)2H and Zn2(OH)3 compounds could also be observed. To our knowledge this is the first evidence for the occurrence of neutral ZnO and ZnOH molecules in a molecular beam. 相似文献
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David Quiñonero Antonio Frontera Salvador Tomàs Guillem A. Suñer Jeroni Morey Antoni Costa Pau Ballester Pere M. Deyà 《Theoretical chemistry accounts》2000,104(1):50-66
A computational study of the mechanism of host–guest complexation between quaternary ammonium compounds and squaramido-based
tripodal receptors has been carried out. Semiempirical molecular orbital calculations, which are in qualitative agreement
with experimental results have been performed using the PM3 Hamiltonian. Molecular interaction potential (MIP) maps were used
to analyze the suitability of both host and guest binding units for a high-affinity recognition process. MIP calculations
were computed from PM3 wavefunctions of the corresponding ammonium cations and dimethyl squaramide as a model compound for
the hydrogen-bond-acceptor unit of the receptors. MIP analyses are helpful for understanding the host–guest process from the
point of view of the double-complementarity principle.
Received: 23 June 1999 / Accepted: 22 September 1999 / Published online: 17 January 2000 相似文献
10.
The ability to use calculated OH frequencies to assign experimentally observed peaks in hydrogen bonded systems hinges on the accuracy of the calculation. Here we test the ability of several commonly employed model chemistries—HF, MP2, and several density functionals paired with the 6‐31+G(d) and 6‐311++G(d,p) basis sets—to calculate the interaction energy (De) and shift in OH stretch fundamental frequency on dimerization (δ(ν)) for the H2O → H2O, CH3OH → H2O, and H2O → CH3OH dimers (where for X → Y, X is the hydrogen bond donor and Y the acceptor). We quantify the error in De and δ(ν) by comparison to experiment and high level calculation and, using a simple model, evaluate how error in De propagates to δ(ν). We find that B3LYP and MPWB1K perform best of the density functional methods studied, that their accuracy in calculating δ(ν) is ≈ 30–50 cm?1 and that correcting for error in De does little to heighten agreement between the calculated and experimental δ(ν). Accuracy of calculated δ(ν) is also shown to vary as a function of hydrogen bond donor: while the PBE and TPSS functionals perform best in the calculation of δ(ν) for the CH3OH → H2O dimer their performance is relatively poor in describing H2O → H2O and H2O → CH3OH. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010 相似文献
11.
Sabu A Kondo S Saito R Kasai Y Hashimoto K 《The journal of physical chemistry. A》2005,109(9):1836-1842
The intermolecular potential energy surface of O(2)-H(2)O was investigated at ab initio MP2 and MRSDCI levels using the aug-cc-pVTZ basis set. The vibrational levels were evaluated by numerically solving the Schr?dinger equations for the nuclear motions with the ab initio potential functions using one- to three-dimensional finite-element methods. On the basis of the calculated partition functions, the equilibrium constant of the complex, K(p), was studied. The K(p) values at atmospheric temperatures of 200-300 K were found to be 1-2 orders of magnitude less than previous estimates from the harmonic oscillator approximation. 相似文献
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Ang-yang Yu 《Structural chemistry》2014,25(2):607-615
The mechanisms and the kinetics of the OH radical reaction with 4-hydroxy-2-butanone (4H2B) are investigated theoretically. Five hydrogen-abstraction channels are identified for the title reaction. The first potential energy profile of the title reaction is presented. The rate constants for each reaction channel are evaluated using transition state theory method in the temperature range of 200–1,000 K. Branching ratio of the title reaction is calculated and plotted. It is shown that the “in-plane hydrogen abstraction” from the methoxy end is the dominant channel, and the other hydrogen-abstraction channels play the minor role. The comparison between theoretical and experimental results is discussed. The three-parameter Arrhenius expression for the rate constants is also provided. 相似文献
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U. Müller Th. Bubel G. Schulz 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1993,25(2):167-174
The optical emission spectrum in the near ultraviolet and visible following electron impact on H2O was studied in a crossed-beam and a static gas-target experiment. Emissions of H*, OH*, OH+*, and H2O+* fragments were detected and absolute emission cross sections for the different fragments were determined. A nonthermal rotational population was observed for the diatomic fragments which gives insight into the dissociation process. Further conclusions on the dissociation mechanism are possible based on appearance potentials and the shape of the emission cross sections as a function of impact energy. 相似文献
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The cooperativity between the O-H...O and C-H...O hydrogen bonds has been studied by quantum chemical calculations at the MP2/6-311++G(d,p) level in gaseous phase and at the B3LYP/6-311++G(d,p) level in solution. The interaction energies of the O-H...O and C-H...O H-bonds are increased by 53 and 58%, respectively, demonstrating that there is a large cooperativity. Analysis of hydrogen-bonding lengths, OH bond lengths, and OH stretching frequencies also supports such a conclusion. By NBO analysis, it is found that orbital interaction plays a great role in enhancing their cooperativity. The strength increase of the C-H...O H-bond is larger than that of the O-H...O H-bond due to the cooperativity. The solvent has a weakening effect on the cooperativity. 相似文献
18.
《Spectrochimica Acta Part B: Atomic Spectroscopy》2003,58(2):249-257
From the application point of view, gas temperature is one of the most important parameters for atmospheric plasmas. Based on the fact that the gas temperature is closely related with the rotational temperature of an atmospheric plasma, a spectroscopic method of measuring the rotational temperature is described in this work by analyzing OH, O2 and N2+ molecular spectra emitted from the atmospheric plasma in ambient air. The OH and N2+ molecular spectra are emitted because of the oxygen, hydrogen and nitrogen atoms existing in the ambient air. The O2 diatomic molecular spectrum is emitted from the oxygen plasma that is frequently produced for atmospheric plasma applications. In order to utilize a spectrometer with modest spectral resolution, a synthetic diatomic molecular spectrum was compared with the experimentally obtained spectrum. The rotational temperatures determined by the above three different molecular spectra are in good agreement within 2.4% error. In the case of a plasma with low gas temperature, the temperature measured by a thermocouple was compared to verify the accuracy of the spectroscopic method, and the results show excellent agreement. From the study, it was found that an appropriate diatomic molecular species can be chosen to be used as a thermometer depending on experimental circumstances. 相似文献
19.
Hydrothermal investigations in the system MgO/B2O3/P2O5(/H2O) yielded two new magnesium borophosphates, Mg2(H2O)[BP3O9(OH)4] and Mg(H2O)2[B2P2O8(OH)2]·H2O. The crystal structures were solved by means of single crystal X‐ray diffraction. While the acentric crystal structure of Mg2(H2O)[BP3O9(OH)4] (orthorhombic, P212121 (No. 19), a = 709.44(5) pm, b = 859.70(4) pm, c = 1635.1(1) pm, V = 997.3(3) × 106 pm3, Z = 4) contains 1D infinite chains of magnesium coordination octahedra interconnected by a borophosphate tetramer, Mg(H2O)2[B2P2O8(OH)2]·H2O (monoclinic, P21/c (No. 14), a = 776.04(5) pm, b = 1464.26(9) pm, c = 824.10(4) pm, β = 90.25(1)°, V = 936.44(9) × 106 pm3,Z = 4) represents the first layered borophosphate with 63 net topology. The structures are discussed and classified in terms of structural systematics. 相似文献