An Ab initio study of reactions in the H3BO3/B2O3/H2O system

The H₃BO₃ ? HBO₂ + H₂O, HBO₂ + HBO₂ ? (HBO₂ · HBO₂) complex, and (HBO₂ · HBO₂) ? B₂O₃ + H₂O reactions of forward and reverse conversion of H₃BO₃ into B₂O₃ and the (HBO₂ · HBO₂) ? (HBO₂)₂ reactions of forward and reverse transformation of the complex into a fairly stable dimer (HBO₂)₂ were studied ab initio at the MP2/6-31+G*//6-31+G* level. The transition state method and calculated equilibrium constants were used to determine forward and reverse reaction constants.     

配合物La（C5O3H3）3·C12H8N2·H2O的合成和表征

本以α－呋喃甲酸（Ｃ５Ｏ３Ｈ４）和邻菲罗啉（Ｃ１２Ｈ８Ｎ２）为配体,在乙醇８溶剂中与硝酸镧反应,合成了与稀土离子Ｌａ（Ⅲ）的三元混配配合物。经元素分析确定其配合物的组成为Ｌａ（Ｃ５Ｏ３Ｈ３）·Ｃ１２Ｈ８Ｎ２·Ｈ２Ｏ,同时还通过了ＩＲ、＾１ＨＮＭＲ、ＵＶ、ＴＧ－ＤＴＡ等谱光的测试与分析,表征了配合物的组成结构和性质。ＩＲ、＾１ＨＮＭＲ和ＵＶ谱的分析结果表明配体羧酸是以脱质子的酸根形式与中心稀土离子     

New Results for Radiative 2H3H Capture at Astrophysical Energies

Russian Physics Journal - Within the framework of the modified potential cluster model with forbidden states which follow from the classification of orbital states of the clusters according to the...     

A shock-tube study of NH3 and NH3/H2 oxidation using laser absorption of NH3 and H2O

Ammonia (NH₃) is an attractive carbon-free fuel, yet its low reactivity presents many challenges for direct use in combustion applications. These combustion challenges could be resolved by mixing NH₃ with more reactive fuels such as hydrogen (H₂). To further contribute to NH₃ and NH₃/H₂ kinetics—which arguably still requires much improvement—new experiments were conducted over a wide range of temperatures (1474–2307 K), near-atmospheric pressure, several NH₃/O₂ mixtures (equivalence ratios varying from 0.56 to 2.07), and near-stoichiometric NH₃/H₂/O₂ mixtures with NH₃:H₂ ratios of 80:20 and 50:50. During these experiments, laser absorption diagnostics near 10.4 µm and 7.4 µm were simultaneously employed to measure NH₃ and H₂O time histories, respectively. Characteristic parameters, such as NH₃ half-life time and H₂O induction delay time, were extracted from the time-history profiles, and these parameters present stringent speciation targets for mechanism validation. After an assessment of most modern kinetics models, three, most accurate, mechanisms were compared against the experimental results. Only one model was able to partially reproduce the pure NH₃ experiments, yet none of the models were capable of predicting the NH₃/H₂ experiments. Reaction pathway analysis showed that NH₃ oxidation proceeds via forming NH₂ then followed three different routes to form N₂. Importantly, the models considered showed different levels of importance for each route. Sensitivity analysis showed that the NH₃/H₂ experiment is mostly sensitive to NH₃+OH⇄NH₂+H₂O. Interestingly, this reaction showed no sensitivity for the NH₃/O₂ experiments. Overall, the models exhibited significantly slower reactivity than the NH₃/H₂ experiments, and the kinetics analysis showed that the start of this reactivity is governed by the levels of H-atoms in the early stages of the experiments. At these early stages of the experiments, propagation and branching reactions in the H₂/O₂ system are the main contributors to generating H radicals, along with the reaction NH₃+H⇄NH₂+H₂ which proceeds in its reverse direction.     

Interaction of Muons with H2/H3-Centres in Diamond

We report on transverse field muon spin rotation measurements on a nitrogen-rich type Ia diamond, both before and after the conversion of some of the aggregated nitrogen centres to nitrogen-vacancy complexes known as H2/H3-centres. The prompt fractions f and the spin relaxation rates λ were determined for the diamagnetic (μ_d) and the paramagnetic (Mu_T) states in the temperature range 10–300 K. The production of the nitrogen-vacancy complexes had little effect on the parameters of the Mu_T state for which f and λ remained unchanged at approximately 30% and 4 μs⁻¹, respectively. For the μ_d state, on the other hand, the formation of the H2/H3-centres resulted in an increase of the prompt fraction from 10(2)% to 20(3)%, and (for the first time) the spin relaxation rate showed a non-zero value of 0.020(3) μs⁻¹. These results show evidence of strong μ_d interactions with the nitrogen-vacancy complexes in diamond, and suggest a more complex structure for this state than a bare μ⁺. This revised version was published online in September 2006 with corrections to the Cover Date.     

Proton conductivity in the layer compound H3OUO2AsO4·3H2O (HU As)

The proton conductivity in H₃OUO₂AsO₄·3H₂O (HUAs) has been measured below the transition temperature at 299 K. A consistent picture of the elementary process taking place is developed from separate electrochemical, spectroscopic and calorimetric measurements. The conductivity is proposed to occur by the “vehicle mechanism” of proton transport, i.e. the cooperative motion of H₃O⁺ and H₂O. This mechanism is compared with the Grotthuss and the simple ion hopping mechanism.     

Study of angular asymmetries in the 2H(α, 3He)3H reaction

The Barshay-Temmer theorem predicts that the angular distribution of the products of the reaction ²H(α, ³He)³H will be symmetric about 90° in the c.m. system. Recently, asymmetries have been reported in the angular distribution in excess of 10 % at some angles. These asymmetries clearly violate the theorem. In an effort to explain the asymmetry as well as describe the angular distribution an exact finite-range multi-interaction DWBA calculation, which includes all appropriate one-particle transfer reaction mechanisms, was employed. Semi-realistic three-nucleon wave functions were utilized in one case in deriving the form factors appropriate for two-particle clustering of the tri-nucleon systems and various Coulomb effects associated with the interactions were included. It was found that both the asymmetry and angular distribution are well described within the present formalism.     

Adsorption and diffusion behaviors of H2, H2S,NH3, CO and H2O gases molecules on MoO3 monolayer: A DFT study

Molybdenum trioxide (MoO₃) with α-phase is a promising material for gas sensing because of its high sensitivity, fast response and thermodynamic stability. To probe the mechanism of superior gas detection ability of MoO₃ monolayer, the adsorption and diffusion of H₂, H₂S, NH₃, CO and H₂O molecules on two-dimensional (2D) MoO₃ layer are studied via density functional theory (DFT) calculations. Based on calculated adsorption energies, density of states, charge transfer, diffusion barriers and diffusion coefficient, MoO₃ shows a superior sensitive and fast response to H₂ and H₂S than CO, NH₃, H₂O, which is consistent with experimental conclusions. Moreover, the response of MoO₃ to H₂S and H₂ will be obviously enhanced at high gas concentration, and the incorporation of H₂ and H₂S results in an obvious increasing in DOS near Fermi level. Our analysis provides a conceptual foundation for future design of MoO₃-based gas sensing materials.     

Crystal structure of di-(L-serine) phosphate monohydrate [C3O3NH7]2H3PO4H2O

The crystal structure of di-(L-serine) phosphate monohydrate [C₃O₃NH₇]₂H₃PO₄H₂O is determined by single-crystal x-ray diffraction. The intensities of x-ray reflections are measured at temperatures of 295 and 203 K. The crystal structure is refined using two sets of intensities. It is established that, in the structure, symmetrically nonequivalent molecules of L-serine occur in two forms, namely, the monoprotonated positively charged molecule CH₂(OH)CH(NH₃)⁺COOH and the zwitterion CH₂(OH)CH(NH₃)⁺COO^?, which are linked with each other and with the H₂PO ^?₄ ion through a hydrogen-bond system involving water molecules.

     

Eu（C8H7O3）3·C12N2·H2O配合物的合成与表征

合成了新的Eu(C8H7O3)3·C12H8N2·H2O配合物.并经元素分析、摩尔电导、IR、UV、1H NMR等表征,初步确定配体3-甲氧基苯甲酸以桥式双齿形式和Eu(Ⅲ)配位.     

H3 PAuPh与(H3PAu)2(1,4-C6H4)2光谱性质的密度泛函研究

用密度泛函(DFT)方法优化了配合物H3 PAuPh(a),(H3 Pau)2(1,4-C6 H4)2(b)的基态的几何结构,并用含时密度泛函方法计算了它们的吸收光谱.结果表明配合物a与b的最低能量吸收谱线的波长分别为257.5 nm和307.6nm,皆具有C(2p)→Au(6p)电荷转移参与下的Px(芳环)→px>(芳环)跃迁本质,并伴有Au(5d)→Au(6p)的金属中心电荷转移性质.配合物b是由两个配合物a相连接而成,配合物b的分子轨道也是由配合物a的分子轨道组合而成.由于轨道组合中存在px或Px相互作用,配合物b的最低能量吸收谱线的波长大于配合物a的相应值.     

Phase transitions and lattice dynamics in Ag2H3IO6 and (NH4)2H3IO6

The investigation of thermal, optical and dielectric properties of Ag₂H₃IO₆ and (NH₄)₂H₃IO₆ revealed phase transitions in two steps with unknown intermediate phases. Reflectivity measurements in the far infrared region confirm that the main step is caused by a freezing in of the proton tunnelling modes. From the results of NMR-NQR-spectroscopy the low temperature structures for both compounds are deduced. The complete group analysis of lattice vibrations and proton ordering modes of the room temperature phases is performed. In the case of Ag₂H₃IO₆ the transitions can be discussed in the frame-work of the Landau theory, starting with a condensation of an antiphase vibration of the silver atoms in theF point of the trigonal Brillouin zone, whereas in the case of (NH₄)₂H₃IO₆ a simultaneous ordering of protons inZ, F, andL-points of the Brillouin zone is proposed for the first step. A new definition of antiferroelectric transitions is suggested which is based on symmetry arguments only. The proton-ordering transitions in both compounds can then be classified as antiferroelectric.     

Chemisorbed phases of H2O on TiO2 and SrTiO3

Ultraviolet photoemission spectroscopy in ultrahigh vacuum has been used to study the interaction of H₂O with argon-ion-bombarded and annealed TiO₂(110) and SrTiO₃ (100) surfaces. At low exposure, evidence is found for the presence of the OH free radical on both bombarded and annealed TiO₂. At high exposure, a spectrum of slightly perturbed adsorbed H₂O is observed, with the a₁ molecular orbital shifted 0.5–1 eV toward tighter binding. This suggests that H₂O binds to the surface of TiO₂ via its a₁, in-plane O lone-pair orbital. No evidence is found for OH on the surface of SrTiO₃. The spectrum of H₂O adsorbed on bombarded SrTiO₃ shows both the a₁ and b₂ molecular orbitals shifted 0.4 toward tighter binding, indicating a more complicated bonding to the surface. For SrTiO₃ that has been bombarded and then annealed, the spectrum of adsorbed H₂O shows no significant bonding effects.     

The catalytic effects of H2CO3, CH3COOH,HCOOH and H2O on the addition reaction of CH2OO + H2O → CH2(OH)OOH

The addition reaction of CH₂OO + H₂O → CH₂(OH)OOH without and with X (X = H₂CO₃, CH₃COOH and HCOOH) and H₂O was studied at CCSD(T)/6-311+ G(3df,2dp)//B3LYP/6-311+G(2d,2p) level of theory. Our results show that X can catalyse CH₂OO + H₂O → CH₂(OH)OOH reaction both by increasing the number of rings, and by adding the size of the ring in which ring enlargement by COOH moiety of X inserting into CH₂OO···H₂O is favourable one. Water-assisted CH₂OO + H₂O → CH₂(OH)OOH can occur by H₂O moiety of (H₂O)₂ or the whole (H₂O)₂ forming cyclic structure with CH₂OO, where the latter form is more favourable. Because the concentration of H₂CO₃ is unknown, the influence of CH₃COOH, HCOOH and H₂O were calculated within 0–30 km altitude of the Earth's atmosphere. The results calculated within 0–5 km altitude show that H₂O and HCOOH have obvious effect on enhancing the rate with the enhancement factors are, respectively, 62.47%–77.26% and 0.04%–1.76%. Within 5–30 km altitude, HCOOH has obvious effect on enhancing the title rate with the enhancement factor of 2.69%–98.28%. However, compared with the reaction of CH₂OO + HCOOH, the rate of CH₂OO···H₂O + HCOOH is much slower.     

H2+和H3+系统的电子频谱与高次谐波谱

针对单电子H2+和双电子H3+系统,采用对称分裂算符法求解波函数的时间演化。计算了电子的含时频谱和体系的高次谐波谱,结果表明:电子频谱和高次谐波谱呈互补规律,即电子频谱峰值出现在基波的偶数倍频率位置,高次谐波则出现在奇数位置。对高次谐波谱随软化库仑参数的变化规律进行了数值研究,发现只在软化库仑参数的一定范围内才产生高次谐波,对该现象作了解释。     

1H NMR study of N(CH3)4H(ClF2CCOO)2

The proton spin–lattice relaxation times and ¹H NMR second moments were measured over a wide range of temperature. The results were compared with those of the ¹⁹F NMR relaxation that we obtained earlier. For both nuclear species, the evolution of the longitudinal magnetizations with time is observed to be strongly bi-exponential and were in good quantitative agreement with the cross-relaxation theory.     

H2（V=3）+H2（He）碰撞中的转动能量转移

激发态Na₂与H₂碰撞,使H₂（V=3,J=3）得到布居,在H₂和He总气压为800 Pa及温度为700 K的条件下,利用相干反斯托克斯拉曼散射（CARS）光谱技术研究了H₂（3,3）与H₂（He）间转动能量转移过程.改变CARS激光束与激发Na₂的激光之间的延迟时间,测量He不同摩尔配比时H₂（3,J）态CARS谱强度的时间演化,得到H₂（3,3）的总弛豫速率系数分别为k_3,3^H₂=（21士5）×10^-3cm³·s^-1和k_3,3^H_e=（5.6士1.6）×10^-13cm³·s^-1.测量H₂（3,J）各转动态的相对CARS谱强度,由速率方程分析,得到H₂（3,3）+H₂→H₂（3,J）+H₂中,对于J=2,4,转移速率系数分别为（11±4）×10^-13cm³·s^-1和（8.2±3.1）×10^-13cm³·s_<sup>-1.在H₂（3,3）+He→H₂（3,J）+He中,对于J=2,4,转移速率系数分别为（3.1±1.2）×10^-13cm³·s^-1和（2.1士0.7）×10¹³cm³·s^-1.对于H₂（3,3）,单量子弛豫|△J|=1约占该态总弛豫率的90%.