Calculations of Chemical Reaction Dynamics for D+ H_2(j_i,ν_i=0)→DH(j_f, ν_f=0) + H

The constant Centrifugal potential approximation is Corrected so as to apply to the reactions of rotational excited reactants for D + H2 (j,, νi = 0 ) -DH(jf, νf = 0) + H. Our results show that the contributions from ji≠0 and Ωi terms are not negligible.

Mechanism analysis of reaction S+(2D)+H2(X1Σg^+) → SH+(X3Σ-) + H(2S) based on the quantum state-to-state dynamics

We present a state-to-state dynamical calculation on the reaction S++ H2→ SH+ +H based on an accurate X2 A″ potential surface. Some reaction properties, such as reaction probability, integral cross sections, product distribution, etc.,are found to be those with characteristics of an indirect reaction. The oscillating structures appearing in reaction probability versus collision energy are considered to be the consequence of the deep potential well in the reaction. The comparison of the present total integral cross sections with the previous quasi-classical trajectory results shows that the quantum effect is more important at low collision energies. In addition, the quantum number inversion in the rotational distribution of the product is regarded as the result of the heavy–light–light mass combination, which is not effective for the vibrational excitation. For the collision energies considered, the product differential cross sections of the title reaction are mainly concentrated in the forward and backward regions, which suggests that there is a long-life intermediate complex in the reaction process.

Visualization of atomic scale reaction dynamics of supported nanocatalysts during oxidation and ammonia synthesis using in-situ environmental(scanning) transmission electron microscopy

Reaction dynamics in gases at operating temperatures at the atomic level are the basis of heterogeneous gas-solid catalyst reactions and are crucial to the catalyst function.Supported noble metal nanocatalysts such as platinum are of interest in fuel cells and as diesel oxidation catalysts for pollution control,and practical ruthenium nanocatalysts are explored for ammonia synthesis.Graphite and graphitic carbons are of interest as supports for the nanocatalysts.Despite considerable literature on the catalytic processes on graphite and graphitic supports,reaction dynamics of the nanocatalysts on the supports in different reactive gas environments and operating temperatures at the single atom level are not well understood.Here we present real time in-situ observations and analyses of reaction dynamics of Pt in oxidation,and practical Ru nanocatalysts in ammonia synthesis,on graphite and related supports under controlled reaction environments using a novel in-situ environmental(scanning) transmission electron microscope with single atom resolution.By recording snapshots of the reaction dynamics,the behaviour of the catalysts is imaged.The images reveal single metal atoms,clusters of a few atoms on the graphitic supports and the support function.These all play key roles in the mobility,sintering and growth of the catalysts.The experimental findings provide new structural insights into atomic scale reaction dynamics,morphology and stability of the nanocatalysts.

The characteristics of O+HD(v = 0,j = 0) reaction dynamics

The analytical potential energy function of HDO is constructed at first using the many-body expansion method. The reaction dynamics of O＋HD （v = 0, j = 0） in five product channels are all studied by quasi-classical trajectory （QCT） method. The results show that the long-lived complex compound HDO is the dominant product at low collision energy. With increasing collision energy, O＋HD → OH＋D and O＋HD → OD＋H exchange reactions will occur with remarkable characteristics, such as near threshold energies, different reaction probabilities, and different reaction cross sections, implying the isotopic effect between H and D. With further increasing collision energy （e.g., up to 502.08 kJ/mol）, O＋HD → O＋H＋D will occur and induce the complete dissociation into single O, H, and D atoms.

Dynamics of Ore-Forming Processesof the Stratabound Skarn Copper Depositsof Tongling, Anhui Province

The skarn and ore bodies of the stratabound skarn copper deposits of Tongling, Anhui Province, are both controlled by definite stratigraphic horizons, and they are concordant with the strata. They occur as layers and layer-like bodies in permeable carbonate rocks of the Middle-Upper Carboniferous Huanglong and Chuanshan Formations which are underlain by impermeable shale or siliceous rocks of the Upper Devonian Wutong Formation. The authors study the dynamics of ore-forming processes of the ore deposits with the dynamic model of coupled transport and reaction, and the following results are obtained: The salinity gradient and flow rate of the ore-forming fluids can both promote the mixing and reaction of juvenile water and formation water, and the permeable strata are favourable sites for the intense transport-reaction of mixing and the formation of deposits. (2) As isothermal transport-reaction took place along the bedding of strata, the moving transport-reaction front formed at the contact between the ore-forming fluids and the rocks advanced slowly along the permeable strata, and then stratiform skarn and ore bodies concordant with the strata were formed. (3) The gradient transport-reaction taking place across the isotherms in the cross-bedding direction caused the mineralogical composition to alter gradually from magnesian skarn to sulphide ore bodies.

The Dynamics of Acid Treatment in the Preparation of Porous Glass

The phase-separation glasses with composition of Na 2O(9.0)B 2O 3(25.0)-SiO 2(66.0)(in mole ratio)were leached with hydrochloric acid,and porous glasses were prepared.The dynamics of the acid treatment was investigated.The effects of treatment time,temperature and acid concentration on the acid treatment process were studied using HCl as treatment solution.The dynamics equation and apparent activation energy obtained in acid treatment process were dw/dt=a/2t and E=57.74 kJ·mol -1,respectively.The constants of the reaction rate at different temperatures were calculated.On the basis of experimental data the mechanism of acid treatment process and the source of swollen stress,which was the main stress during treatment process,were discussed.

A NEW DYNAMIC MODEL FOR STUDY OF DISLOCATION PATTERN FORMATION

Based on the principle given in nonlinear diffusion-reaction dynamics, a new dynamic model for dislocation patterning is proposed by introducing a relaxation time to the relation between dislocation density and dislocation flux. The so-called chemical potential like quantities, which appear in the model can be derived from variation principle for free energy functional of dislocated media, where the free energy density function is expressed in terms of not only the dislocation density itself but also their spatial gradients. The Linear stability analysis on the governing equations of a simple dislocation density shows that there exists an intrinsic wave number leading to bifurcation of space structure of dislocation density. At the same time, the numerical results also demonstrate the coexistence and transition between different dislocation patterns.

Time-dependent density functional theoretical studies on the photo-induced dynamics of an HCI molecule encapsulated in C60 under femtosecond laser pulses

By using first-principles simulations based on time-dependent density functional theory, the chemical reaction of an HCl molecule encapsulated in C60 induced by femtosecond laser pulses is observed. The H atom starts to leave the Cl atom and is reflected by the C60 wall. The coherent nuclear dynamic behaviors of bond breakage and recombination of the HCl molecule occurring in both polarized parallel and perpendicular to the H-Cl bond axis are investigated. The radial oscillation is also found in the two polarization directions of the laser pulse. The relaxation time of the H-Cl bond lengths in transverse polarization is slow in comparison with that in longitudinal polarization. Those results are important for studying the dynamics of the chemical bond at an atomic level.

A semiclassical molecular dynamics of the photochromic ring-opening reaction of spiropyran

The photochromic ring-opening reaction of spiropyran（SP） has been investigated by a realistic semiclassical dynamics simulation,accompanied by SA3-CASSCF（12 10）/MS-CASPT2 potential energy curves（PECs） of S0–S2.The main simulation results show the dominate pathway corresponds to the ringopening process of trans-SP to form the most stable merocyanine（MC） product.These findings provide more important complementarity for interpreting experimental observations.

Comprehensive Investigations of the Cl+CH_(3)OH→HCl+CH_(3)O/CH_(2)OH Reaction:Validation of Experiment and Dynamic Insights

Cl+CH_(3)OH→HCl+CH_(3)O/CH_(2)OH is a prototypical multiple-channel reaction.Experimentally,ample dynamical and kinetic information is available,but there are still many uncertainties concerning the reaction mechanism.Theoretical investigations are rare due to the absence of a potential energy surface(PES),which has greatly hindered our understanding of the reaction dynamics.Using a machine-learning approach,an accurate full-dimensional PES for the title reaction based on tens of thousands of high-level ab initio data is reported.Comprehensive dynamical calculations were performed on the PES using quasi-classical trajectories,and the results provide insights into the reaction kinetics and dynamics.The calculated non-Arrhenius rate coefficients are consistent with the experimental data,attributable to a complex-forming mechanism at low temperatures.At high energies,the reaction is dominated by a direct mechanism,which results in dominant forward scattering via a stripping mechanism augmented by less prominent sideways and backward scattering via a rebound mechanism.At collision energies of 5.6 and 8.7 kcal/mol,the measured product translational energy and ro-vibrational state distributions of HCl are well reproduced.In addition,mode specificity is revealed and rationalized by the sudden vector projection model.This work sheds valuable light on the microscopic mechanism and dynamics of this prototypical multichannel reaction.

Representative Elementary Volume(REV) in Spatio-Temporal Domain： A Method to Find REVfor Dynamic Pores

One of the potential risks associated with subsurface storage of CO_2 is the seepage of CO_2 through existing faults and fractures. There have been a number of studies devoted to this topic. Some of these studies show that geochemistry, especially mineralization, plays an important role in rendering the faults as conduits for CO_2 movement while others show that mineralization due to CO_2 injection can result in seep migration and flow diversion. Therefore, understanding the changes in reservoir properties due to pore alterations is important to ensure safe long term CO_2 storage in the subsurface. We study the changes in the Representative Elementary Volume（REV） of a rock due to reactive kinetics over a time, using a statistical approach and pore-scale CO_2-rock interactiondata.The goal of this study is to obtain the REV of a rock property that accounts for pore-scale changes over time due to reactive kinetics, and we call this as spatiotemporal REV. Scale-up results suggest that the REV changes with time when CO_2-rock interaction is considered. It is hypothesized that the alteration in pore structure introduces more heterogeneity in the rock, and because of this the magnitude of REV increases. It is possible that these noticeable changes in REV at pore-scale may have an impact when analyzed at the reservoir scale.

Rosin side chain type catalyst-free vitrimers with high cross-link density,mechanical strength,and thermal stability

The emergence of vitrimer,a new class of polymer materials can address the problem of recyclability,reprocess ability and recyclability of thermosetting plastics.Rosin,a natural product,is an ideal raw material for the preparation of polymers in a more sustainable way.Nevertheless,due to the huge steric hindrance caused by the hydrogenated phenanthrene ring structure,the cross-link density of materials is frequently lowered.In this study,hydrogenated rosin was adopted for preparing hydrogenated rosin side-chain type diacids,which were reacted with mixed epoxy to obtain rosin side-chain type vitrimers.It was completely characterized by differential scanning calorimetry test,thermogravimetric analysis,shape memory test and self-healing test.The prepared vitrimers exhibited good self-healing properties,excellent heat resistance(T_(d)=352℃)as well as high mechanical properties(tensile strength of 46.75 MPa).The tricyclic diterpene structure of rosin was introduced into the side chain in order to avoid the reduction of cross-link density resulting from the huge steric hindrance of the rigid tricyclic hydrophenylene skeleton.Vitrimers can undergo dynamic transesterification reaction without external catalysts due to the autocatalytic effect of tertiary amines from epoxy.Moreover,our work expanded the application field of rosin,increased the added value of rosin,and provided a novel method for preparing rosin-based vitrimers with ideal properties.

In-Situ Synchrotron Radiation Infrared Spectroscopic Identification of Reactive Intermediates over Multiphase Electrocatalytic Interfaces

A comprehensive understanding of the microscopic reaction mechanisms at the gas-solid-liquid electrochemical interfaces is urgently required for the development of advanced electrocatalysts applied in burgeoning sustainable energy conversion systems. In-situ synchrotron radiation Fourier transform infrared(SR-FTIR) spectroscopy is one of the most powerful techniques for investigating the evolving dynamics of reactive intermediates during electrocatalytic reactions. In this review, we methodically summarize the recent progress in the research of dynamic mechanisms for valuable electrocatalytic reactions based on in-situ SR-FTIR methodology. Moreover, the merits and drawbacks of SRFTIR spectroscopy, the design principles of infrared beam setups and in-situ cells, as well as the in-situ measurement criteria are also discussed in detail. Lastly, the potential challenges and opportunities in this field are prudently stated. This review is expected to stimulate a broad interest in the material science and electrochemistry communities for exploring the dynamic mechanisms of prominent catalysis at the atomic/molecular level by using SR-based spectroscopy.

形状记忆聚己内酯/氧化钨纳米线复合薄膜的光导二维到三维变形结构

形状记忆材料在受到外部刺激时具备可编程的复杂形状和大变形,该特性对其潜在应用至关重要.通常情况下将平面二维结构转化为复杂三维结构需要设计非对称的或双层薄膜结构.在本工作中,我们提出了一个简单的策略以实现二维到三维结构的转变,即可以通过激光刺激预拉伸复合薄膜的特定点进而变形成各种预先确定的形状序列.具体的,将吸光性W18O49纳米线物理掺杂到丙烯酸封端的聚己内酯交联网络中,当用98 mW cm^(−2)的激光刺激复合薄膜时,温度梯度和单层薄膜在厚度维度上的单畴取向导致形状记忆聚己内酯/W_(18)O_(49)纳米线复合薄膜的面外弯曲变形.紧接着,通过调控激光辐照时间、薄膜厚度和预拉伸应变,可以实现复合薄膜的不同弯曲变形速率和弯曲幅度.此外,通过将预拉伸的平面二维状聚合物薄膜与剪纸技术相结合,复合薄膜在受激后可以朝着更为复杂的三维形状发生变化.通过激活同一薄膜内的动态酯交换反应也可以实现聚己内酯基复合薄膜的二维到三维形状转化.因此这种新型薄膜在生物医学器件或软机器人领域具有巨大的应用潜力.