Ab initio rate coefficients for reactions of 2,5-dimethylhexyl isomers with O2: temperature- and pressure-dependent branching ratios

2021 ◽  
Vol 23 (10) ◽  
pp. 6225-6240
Author(s):  
Mohamad Akbar Ali
Keyword(s):  
Ab Initio ◽  
Branching Ratios ◽  
Rate Coefficients ◽  
Temperature And Pressure

Pressures-dependence rate coefficients for the formation 2,2,5,5-tetramethyl-tetrahydrofuran.

Rotational de-excitations of C3H+ (1Σ+) by collision with He: new ab initio potential energy surface and scattering calculations

2020 ◽  
Vol 494 (4) ◽  
pp. 5675-5681 ◽  
Author(s):  
Sanchit Chhabra ◽  
T J Dhilip Kumar
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Cross Sections ◽  
Energy Surface ◽  
Molecular Ions ◽  
Basis Set ◽  
Rate Coefficients ◽  
Close Coupling ◽  
Collisional Rate Coefficients

ABSTRACT Molecular ions play an important role in the astrochemistry of interstellar and circumstellar media. C3H+ has been identified in the interstellar medium recently. A new potential energy surface of the C3H+–He van der Waals complex is computed using the ab initio explicitly correlated coupled cluster with the single, double and perturbative triple excitation [CCSD(T)-F12] method and the augmented correlation consistent polarized valence triple zeta (aug-cc-pVTZ) basis set. The potential presents a well of 174.6 cm−1 in linear geometry towards the H end. Calculations of pure rotational excitation cross-sections of C3H+ by He are carried out using the exact quantum mechanical close-coupling approach. Cross-sections for transitions among the rotational levels of C3H+ are computed for energies up to 600 cm−1. The cross-sections are used to obtain the collisional rate coefficients for temperatures T ≤ 100 K. Along with laboratory experiments, the results obtained in this work may be very useful for astrophysical applications to understand hydrocarbon chemistry.

Vibrational branching ratios and radiative lifetimes in the laser cooling of AlBr

2017 ◽  
Vol 19 (7) ◽  
pp. 5519-5524 ◽  
Author(s):  
Yufeng Gao ◽  
Mingjie Wan
Keyword(s):  
Quantum Chemistry ◽  
Ab Initio ◽  
Laser Cooling ◽  
Branching Ratios ◽  
Radiative Lifetimes

The feasibility of laser cooling of the AlBr molecule is investigated usingab initioquantum chemistry.

Barrierless Reactions of Three Benzonitrile Radical Cations with Ethylene

2020 ◽  
Vol 73 (8) ◽  
pp. 705
Author(s):  
Oisin J. Shiels ◽  
P. D. Kelly ◽  
Stephen J. Blanksby ◽  
Gabriel da Silva ◽  
Adam J. Trevitt
Keyword(s):  
Ion Trap ◽  
Radical Cations ◽  
Branching Ratios ◽  
Ring Closure ◽  
Van Der Waals Complexes ◽  
Rate Coefficients ◽  
Ion Trap Mass Spectrometry ◽  
Closure Mechanism ◽  
Product Ions ◽  
Product Branching

Reactions of three protonated benzonitrile radical cations with ethylene are investigated. Product branching ratios and reaction kinetics, measured using ion-trap mass spectrometry, are reported and mechanisms are developed with support from quantum chemical calculations. Reactions proceed via pre-reactive van der Waals complexes with no energy barrier (above the reactant energy) and form radical addition and addition–elimination product ions. Rate coefficients are 4-dehydrobenzonitrilium: 1.72±0.01×10−11 cm3 molecule−1 s−1, 3-dehydrobenzonitrilium: 1.85±0.01×10−11 cm3 molecule−1 s−1, and 2-dehydrobenzonitrilium: 5.96±0.06×10−11 cm3 molecule−1 s−1 (with±50% absolute uncertainty). A ring-closure mechanism involving the protonated nitrile substituent is proposed for the 2-dehydrobenzonitrilium case and suggests favourable formation of the protonated indenimine cation.

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