Rotational cross sections and rate coefficients of aluminium monoxide AlO(X2Σ+) induced by its collision with He(1S) at low temperature

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.

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

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab2451 ◽

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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Electron-impact double ionization of the carbon atom

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834303 ◽

2018 ◽

Vol 620 ◽

pp. A188 ◽

Cited By ~ 6

Author(s):

Valdas Jonauskas

Keyword(s):

Carbon Atom ◽

Electron Impact ◽

Cross Sections ◽

Double Ionization ◽

Impact Excitation ◽

Rate Coefficients ◽

Electron Impact Excitation ◽

Ionization Cross ◽

Ionization Cross Sections ◽

Good Agreement

Electron-impact single- and double-ionization cross sections and Maxwellian rate coefficients are presented for the carbon atom. Scaling factors are introduced for the electron-impact excitation and ionization cross sections obtained in the distorted wave (DW) approximation. It is shown that the scaled DW cross sections provide good agreement with measurements for the single ionization of the C atom and C1+ ion. The direct double-ionization (DDI) process is studied using a multi-step approach. Ionization–ionization, excitation–ionization–ionization, and ionization–excitation–ionization branches are analyzed. It is demonstrated that the three-step processes contribute ≼40% of the total DDI cross sections for the case where one of the electrons takes all of the excess energy after the first ionization process.

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Semiempirical formulae for dipole excitation cross sections and rate coefficients in atoms and ions

Physica Scripta ◽

10.1088/0031-8949/43/3/009 ◽

1991 ◽

Vol 43 (3) ◽

pp. 266-269 ◽

Cited By ~ 2

Author(s):

V P Shevelko

Keyword(s):

Cross Sections ◽

Rate Coefficients ◽

Dipole Excitation ◽

Excitation Cross Sections

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On apparent barrier-free reactions

QUARKS: Brazilian Electronic Journal of Physics, Chemistry and Materials Science ◽

10.34019/2674-9688.2020.v3.30967 ◽

2020 ◽

Vol 3 (1) ◽

pp. 3-8

Author(s):

Maikel Ballester

Keyword(s):

Low Temperature ◽

Chemical Reactions ◽

Rate Constant ◽

Kinetic Models ◽

Rate Coefficient ◽

Minimum Energy ◽

Temperature Limit ◽

Rate Coefficients ◽

Minimum Energy Path ◽

Full Dimension

Rate coefficients of bi-molecular chemical reactions are fundamental for kinetic models. The rate coefficient dependence on temperature is commonly extracted from the analyses of the reaction minimum energy path. However, a full dimension study of the same reaction may suggest a different asymptotic low-temperature limit in the rate constant than the obtained from the energetic profile.

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