scholarly journals Role of Electronic Excited State in Kinetics of the CH2OO + SO2 ! HCHO + SO3 Reaction

2021 ◽  
Author(s):  
Qingfei Song ◽  
Qiuyu Zhang ◽  
Qingyong Meng
Keyword(s):  
Excited State ◽  
Room Temperature ◽  
Energy Surface ◽  
Regression Method ◽  
Vibrationally Excited ◽  
Compute Data ◽  
Ring Polymer ◽  
Experimental Values ◽  
Kinetics Of

In this work, kinetics of the CH2OO + SO2 ! HCHO + SO3 reaction was studied by ring-polymer molecular dynamics (RPMD). To perform RPMD calculations, multi-reference configuration interaction (MRCI) was first carried out to compute data for constructing potential energy surface (PES) through a kernel regression method. On the basis of the present MRCI calculations, the statics multi-state mechanism involving the lowest-lying singlet excited state (denoted by S 1) was proposed, which is di?erent from the previously proposed mechanism with the lowest-lying triplet state (denoted by T1). Moreover, the present RPMD calculations predicted the rate coe?cient of 3:95?10􀀀11cm3 molecule􀀀1s􀀀1 at the room temperature (namely 298 K), agreeing with the previously reported experimental values. Finally, based on the present calculations, a probable dynamics mechanism was discussed, where the produced HCHO molecule was proposed to be in a vibrationally excited state. This needs further experimental and theoretical observation in the future.<br>

scholarly journals Role of Electronic Excited State in Kinetics of the CH2OO + SO2 ! HCHO + SO3 Reaction

2021 ◽  
Author(s):  
Qingfei Song ◽  
Qiuyu Zhang ◽  
Qingyong Meng
Keyword(s):  
Excited State ◽  
Room Temperature ◽  
Energy Surface ◽  
Regression Method ◽  
Vibrationally Excited ◽  
Compute Data ◽  
Ring Polymer ◽  
Experimental Values ◽  
Kinetics Of

In this work, kinetics of the CH2OO + SO2 ! HCHO + SO3 reaction was studied by ring-polymer molecular dynamics (RPMD). To perform RPMD calculations, multi-reference configuration interaction (MRCI) was first carried out to compute data for constructing potential energy surface (PES) through a kernel regression method. On the basis of the present MRCI calculations, the statics multi-state mechanism involving the lowest-lying singlet excited state (denoted by S 1) was proposed, which is di?erent from the previously proposed mechanism with the lowest-lying triplet state (denoted by T1). Moreover, the present RPMD calculations predicted the rate coe?cient of 3:95?10􀀀11cm3 molecule􀀀1s􀀀1 at the room temperature (namely 298 K), agreeing with the previously reported experimental values. Finally, based on the present calculations, a probable dynamics mechanism was discussed, where the produced HCHO molecule was proposed to be in a vibrationally excited state. This needs further experimental and theoretical observation in the future.<br>

Dynamics and kinetics of the Si(1D) + H2/D2 reactions on a new global ab initio potential energy surface

2021 ◽  
Vol 23 (10) ◽  
pp. 6141-6153
Author(s):  
Jianwei Cao ◽  
Yanan Wu ◽  
Haitao Ma ◽  
Zhitao Shen ◽  
Wensheng Bian
Keyword(s):  
Molecular Dynamics ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Quantum Dynamics ◽  
Energy Surface ◽  
Molecular Dynamics Calculations ◽  
Ring Polymer ◽  
Ring Polymer Molecular Dynamics ◽  
Kinetics Of

Quantum dynamics and ring polymer molecular dynamics calculations reveal interesting dynamical and kinetic behaviors of an endothermic complex-forming reaction.

Di-imide: Some Physical and Chemical Properties, and the Kinetics and Stoichiometry of the Gas-phase Decomposition

1973 ◽  
Vol 51 (21) ◽  
pp. 3605-3619 ◽  
Author(s):  
C. Willis ◽  
R. A. Back
Keyword(s):  
Gas Phase ◽  
Room Temperature ◽  
Chemical Properties ◽  
Phase Decomposition ◽  
Important Intermediate ◽  
Long Lifetime ◽  
Physical And Chemical ◽  
Text Formation ◽  
Kinetics Of

Preparation of di-imide by passing hydrazine vapor through a microwave discharge yields mixtures with NH3 containing typically about 15% N2H2, estimated from the gases evolved on decomposition. The behavior of the mixture (which melts at −65 °C) on warming from −196 to −30 °C suggests a strong interaction between the components. Measurements of magnetic susceptibility and e.p.r. experiments showed that N2H2 is not strongly paramagnetic, which with other observations points to a singlet rather than a triplet ground-state.Di-imide can be vaporized efficiently, together with NH3, by rapid warming, and the vapor is surprisingly long-lived, with a typical half-life of several minutes at room temperature. The near-u.v. (3200–4400 Å) absorption spectrum of the vapor was photographed; it shows well-defined but diffuse bands, with εmax = 6(± 3) at 3450 Å.Di-imide decomposes at room temperature in two ways:[Formula: see text][Formula: see text]Formation of NH3 was not observed but cannot be ruled out. The decomposition of the vapor is complicated by a sizeable and variable decomposition that occurs rapidly during the vaporization. The stoichiometry of this and the vapor-phase decomposition depends on total pressure and di-imide concentration. The kinetics of the decomposition of the vapor were studied from 22 to 200 °C by following the disappearance of N2H2 by absorption of light at 3450 Å, or the formation of N2H4 by absorption at 2400 Å, and by mass spectrometry. The kinetics are complex and can be either first- or second-order, or mixed, depending on surface conditions. The effect of olefin additives on the decomposition was studied, and is also complex.Mechanisms for the decomposition are discussed, including the possible role of trans-cis isomerization. The relatively long lifetime found for di-imide in the gas phase suggests that it may be an important intermediate in many reactions of hydronitrogen systems.

scholarly journals Rate Coefficients and Kinetic Isotope Effects of the Cl + XCl  XCl + Cl (X=H, D, Mu) Reactions from Ring Polymer Molecular Dynamics

2020 ◽  
Author(s):  
junhua fang ◽  
Wenbin Fan ◽  
Hui Yang ◽  
Jianing Song ◽  
Yongle Li
Keyword(s):  
Molecular Dynamics ◽  
Free Energy ◽  
Energy Surface ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Rate Coefficients ◽  
Theoretical Methods ◽  
Kinetic Isotope ◽  
Ring Polymer ◽  
Experimental Values

<p>The ring-polymer molecular dynamics (RPMD) was used to calculate the thermal rate coefficients and kinetic isotope effects of the heavy-light-heavy abstract reaction Cl + XCl ® XCl + Cl (X=H, D, Mu). For the Cl + HCl reaction, the excellent agreement between the RPMD and experimental values provides a strong proof for the accuracy of the RPMD theory. And the RPMD results also consistent with results from other theoretical methods including improved-canonical-variational-theory and quantum dynamics. The most novel finding is there is a double peak in Cl + MuCl reaction near the transition state, leaving a free energy well. It comes from the mode softening of the reaction system at the peak of the potential energy surface. Such an explicit free energy well suggests strongly there is an observable resonance. And for the Cl + DCl reaction, the RPMD rate coefficient again gives very accurate results comparing with experimental values. The only exception is at the temperature of 312.5 K, at this temperature, results from RPMD and all other theoretical methods are close to each other but slightly lower than the experimental value, which indicates experimental or potential energy surface deficiency.</p><div><br></div>

scholarly journals Rate Coefficients and Kinetic Isotope Effects of the XCl + Cl (X=H, D, Mu) Reactions from Ring Polymer Molecular Dynamics

2020 ◽  
Author(s):  
junhua fang ◽  
Wenbin Fan ◽  
Hui Yang ◽  
Jianing Song ◽  
Yongle Li
Keyword(s):  
Molecular Dynamics ◽  
Free Energy ◽  
Energy Surface ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Rate Coefficients ◽  
Theoretical Methods ◽  
Kinetic Isotope ◽  
Ring Polymer ◽  
Experimental Values

<p>The ring-polymer molecular dynamics (RPMD) was used to calculate the thermal rate coefficients and kinetic isotope effects of the heavy-light-heavy abstract reaction Cl + XCl ® XCl + Cl (X=H, D, Mu). For the Cl + HCl reaction, the excellent agreement between the RPMD and experimental values provides a strong proof for the accuracy of the RPMD theory. And the RPMD results also consistent with results from other theoretical methods including improved-canonical-variational-theory and quantum dynamics. The most novel finding is there is a double peak in Cl + MuCl reaction near the transition state, leaving a free energy well. It comes from the mode softening of the reaction system at the peak of the potential energy surface. Such an explicit free energy well suggests strongly there is an observable resonance. And for the Cl + DCl reaction, the RPMD rate coefficient again gives very accurate results comparing with experimental values. The only exception is at the temperature of 312.5 K, at this temperature, results from RPMD and all other theoretical methods are close to each other but slightly lower than the experimental value, which indicates experimental or potential energy surface deficiency.</p><div><br></div>

scholarly journals Interstellar nitrile anions: Detection of C3N− and C5N− in TMC-1

2020 ◽  
Vol 641 ◽  
pp. L9 ◽  
Author(s):  
J. Cernicharo ◽  
N. Marcelino ◽  
J. R. Pardo ◽  
M. Agúndez ◽  
B. Tercero ◽  
...  
Keyword(s):  
Excited State ◽  
Strong Support ◽  
Carbon Chain ◽  
Formation Mechanisms ◽  
Circumstellar Envelope ◽  
Vibrationally Excited ◽  
Neutral Radical ◽  
Taurus Region ◽  
Dark Core

We report on the first detection of C3N− and C5N− towards the cold dark core TMC-1 in the Taurus region, using the Yebes 40 m telescope. The observed C3N/C3N− and C5N/C5N− abundance ratios are ∼140 and ∼2, respectively; that is similar to those found in the circumstellar envelope of the carbon-rich star IRC +10216. Although the formation mechanisms for the neutrals are different in interstellar (ion-neutral reactions) and circumstellar clouds (photodissociation and radical-neutral reactions), the similarity of the C3N/C3N− and C5N/C5N− abundance ratios strongly suggests a common chemical path for the formation of these anions in interstellar and circumstellar clouds. We discuss the role of radiative electronic attachment, reactions between N atoms and carbon chain anions Cn−, and that of H− reactions with HC3N and HC5N as possible routes to form CnN−. The detection of C5N− in TMC-1 gives strong support for assigning to this anion the lines found in IRC +10216, as it excludes the possibility of a metal-bearing species, or a vibrationally excited state. New sets of rotational parameters have been derived from the observed frequencies in TMC-1 and IRC +10216 for C5N− and the neutral radical C5N.

scholarly journals Роль модельных представлений в описании кинетики люминесценции гибридных нитевидных нанокристаллов

2020 ◽  
Vol 128 (1) ◽  
pp. 122
Author(s):  
А.С. Кулагина ◽  
А.И. Хребтов ◽  
Р.Р. Резник ◽  
Е.В. Убыйвовк ◽  
А.П. Литвин ◽  
...  
Keyword(s):  
Room Temperature ◽  
Theoretical Models ◽  
Decay Kinetics ◽  
Semiconductor Structures ◽  
Long Duration ◽  
State Radiation ◽  
Radiation Lifetime ◽  
Kinetics Of ◽  
Luminescence Decay Kinetics

On the example of InP/InAsP/InP nanowires, the role of theoretical models in the photodynamics study of hybrid semiconductor structures is considered. The photodynamics of luminescence of an array of InP/InAsP/InP nanowires formed by molecular beam epitaxy on a Si (III) substrate was studied. Based on a comparison of several kinetic models, including the use of poly-exponential and stretched-exponential functions, the analysis of experimental data is carried out. Experiments were performed by excitation with laser radiation of 633 nm at room temperature. It has been shown that the luminescence decay kinetics of the InAsP nanoinsert is best described in terms of the contact quenching model. The total decay time of the excited state (radiation lifetime) of the InAsP insert was estimated at τ ~ 40 ns. The reasons for the unusually long duration of transfer of excitation from InP have been suggested.

Kinetic study of the OH + HO2 → H2O + O2 reaction using ring polymer molecular dynamics and quantum dynamics

2020 ◽  
Vol 22 (41) ◽  
pp. 23657-23664
Author(s):  
Yang Liu ◽  
Hongwei Song ◽  
Jun Li
Keyword(s):  
Molecular Dynamics ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Kinetic Study ◽  
Quantum Dynamics ◽  
Energy Surface ◽  
Title Reaction ◽  
Ring Polymer ◽  
Ring Polymer Molecular Dynamics ◽  
Kinetics Of

The kinetics of the title reaction is studied by running the ring polymer molecular dynamics and quantum dynamics on an accurate potential energy surface.

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