scholarly journals Cross-sections and rate coefficients for rotational excitation of aluminium hydroxide by helium

2018 ◽  
Vol 480 (4) ◽  
pp. 5412-5418 ◽  
Author(s):  
Manel Naouai ◽  
Faouzi Najar ◽  
Cheikh Tidiane Bop ◽  
Kamel Hammami
Keyword(s):  
Cross Sections ◽  
Aluminium Hydroxide ◽  
Rate Coefficients ◽  
Rotational Excitation

Rotational excitation of HNCO by He: potential energy surface, collisional cross-sections and rate coefficients

2017 ◽  
Vol 471 (1) ◽  
pp. 80-88 ◽  
Author(s):  
E. Sahnoun ◽  
Y. Ajili ◽  
K. Hammami ◽  
N.-E. Jaidane ◽  
M. Mogren Al Mogren ◽  
...  
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Cross Sections ◽  
Energy Surface ◽  
Rate Coefficients ◽  
Rotational Excitation

The rotational excitation of carbon monoxide by hydrogen atom impact

1975 ◽  
Vol 342 (1629) ◽  
pp. 191-207 ◽  
Keyword(s):  
Carbon Monoxide ◽  
Cross Sections ◽  
Rate Coefficients ◽  
Rotational Degree ◽  
Rotational Excitation ◽  
Body Frame ◽  
Hydrogen Atoms ◽  
Close Coupling ◽  
Coupling Methods ◽  
Low Energies

A quantal study is carried out of the rotational excitation of carbon monoxide in collision with hydrogen atoms. The interaction potential at short range is constructed semi-empirically and joined to the Buckingham potential at long range. The close-coupling formulation is used to assess the reliability of the fixed-nuclei approximation, which is developed in terms of the adiabatic theory of electron-molecule scattering. The applicability of two simplified close-coupling formulations, introduced by Rabitz and by McGuire & Kouri, is examined. We found that the fixed nuclei method is unpromising at low energies and time-consuming at high energies. The two simplified close-coupling methods are capable of providing results of useful accuracy. The similarity in formulation of the fixed-nuclei and one of the close-coupling methods, both of which are body-frame treatments, and the differences in their results show that the rotational degree of freedom must be treated rigorously. The method of Rabitz is economical, and we adopted it to calculate the energy dependent rotation excitation cross sections for the scattering of H + CO. The results are presented in the form of Maxwellian-averaged rate coefficients in the temperature range of 5-150 K.

scholarly journals Diffusion, Attachment and Attachment Cooling of Thermal Electrons in Oxygen and Oxygen Mixtures

1983 ◽  
Vol 36 (6) ◽  
pp. 831 ◽  
Author(s):  
R Hegerberg ◽  
RW Crompton
Keyword(s):  
Diffusion Coefficient ◽  
Cross Sections ◽  
Rate Coefficient ◽  
Resonance Energy ◽  
Sampling Technique ◽  
Rate Coefficients ◽  
Rotational Excitation ◽  
Attachment Rate ◽  
Excitation Cross Sections ◽  
Three Body

The Cavalieri electron density sampling technique has been used to measure the diffusion and attachment rate coefficients for thermal electrons in O2, and in O2–N2 and O2–C02 mixtures. The observed pressure dependence of the three-body attachment rate coefficient va/N2 is shown to be caused by the selective removal of electrons from the distribution at the attachment resonance energy, and the magnitude of this effect (so-called 'attachment cooling') is shown to be a measure of the magnitude of the rotational excitation cross sections in O2 and N2. Three-body rate coefficients for the formation of O2 involving O2, N2 and CO¯2 as third bodies have been found to be 2.2,011 and 3.5 X 10¯30 cm6 S¯l respectively. The value of the diffusion coefficient ND for thermal electrons in O2 is found to be (37 � 3) x 1021 cm¯1s¯1.

scholarly journals Cross Sections and Rate Coefficients for Rotational Excitation of HeH+ Molecule by Electron Impact

Atoms ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 49 ◽  
Author(s):  
Marjan Khamesian ◽  
Mehdi Ayouz ◽  
Jasmeet Singh ◽  
Viatcheslav Kokoouline
Keyword(s):  
Electron Impact ◽  
Cross Sections ◽  
Theoretical Approach ◽  
Analytical Formula ◽  
Rate Coefficients ◽  
Rotational Excitation ◽  
R Matrix ◽  
Wide Range ◽  
The Uk ◽  
Quantum Defect Theory

Cross sections for rotational excitation and de-excitation of the HeH+ ion by an electron impact are computed using a theoretical approach that combines the UK R-matrix code and the multi-channel quantum defect theory. The thermally-averaged rate coefficients derived from the obtained cross sections are fitted to an analytical formula valid for a wide range of temperatures.

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.

Inelastic scattering of interstellar silyl cyanide (SiH3CN) by helium atoms : cross-sections and rate coefficients for A- and E-SiH3CN

2021 ◽  
Vol 507 (4) ◽  
pp. 5264-5271
Author(s):  
Manel Naouai ◽  
Abdelhak Jrad ◽  
Ayda Badri ◽  
Faouzi Najar
Keyword(s):  
Inelastic Scattering ◽  
Total Energy ◽  
Cross Sections ◽  
Three Dimensional ◽  
Basis Set ◽  
Rate Coefficients ◽  
Close Coupling ◽  
Explicitly Correlated ◽  
Correlation Consistent ◽  
Triple Excitation

ABSTRACT Rotational inelastic scattering of silyl cyanide (SiH3CN) molecule with helium (He) atoms is investigated. Three-dimensional potential energy surface (3D-PES) for the SiH3CN–He interacting system is carried out. The ab initio 3D-PES is computed using explicitly correlated coupled cluster approach with single, double, and perturbative triple excitation CCSD(T)-F12a connected to augmented-correlation consistent-polarized valence triple zeta Gaussian basis set. A global minimum at (R = 6.35 bohr; θ = 90○; ϕ = 60○) with a well depth of 52.99 cm−1 is pointed out. Inelastic rotational cross-sections are emphasized for the 22 first rotational levels for total energy up to 500 cm−1 via close coupling (CC) approach in the case of A-SiH3CN and for the 24 first rotational levels for total energy up to 100 cm−1 via CC and from 100 to 500 cm−1 via coupled states (CS) in the case of E-SiH3CN. Rate coefficients are derived for temperature until 80 K for both A- and E-SiH3CN–He systems. Propensity rules are obtained for |ΔJ| = 2 processes with broken parity for A-SiH3CN and for |ΔJ| = 2 processes with |ΔK| = 0 and unbroken parity for E-SiH3CN.

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