Analytical cross sections and rate coefficients for H-H inelastic collisions

1992 ◽  
Vol 394 ◽  
pp. 717 ◽  
Author(s):  
W. H. Soon
Keyword(s):  
Cross Sections ◽  
Inelastic Collisions ◽  
Rate Coefficients

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 collisions at low energies

1969 ◽  
Vol 47 (10) ◽  
pp. 1723-1729 ◽  
Author(s):  
A. Dalgarno
Keyword(s):  
Energy Loss ◽  
Cross Sections ◽  
Low Energy ◽  
Inelastic Collisions ◽  
Low Energies ◽  
Low Energy Electrons ◽  
The Cross ◽  
Loss Rates

A summary is presented of the processes by which low energy electrons lose energy in moving through the atmosphere and estimates are given of the cross sections and energy loss rates. The mechanisms by which thermal electrons cool are described and the cooling efficiencies are listed.

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.

scholarly journals Electron-impact double ionization of the carbon atom

2018 ◽  
Vol 620 ◽  
pp. A188 ◽  
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.

scholarly journals Breakdown of energy transfer gap laws revealed by full-dimensional quantum scattering between HF molecules

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Dongzheng Yang ◽  
Jing Huang ◽  
Xixi Hu ◽  
Hua Guo ◽  
Daiqian Xie
Keyword(s):  
Energy Transfer ◽  
Angular Momentum ◽  
Vibrational Energy ◽  
Energy Gap ◽  
Inelastic Collisions ◽  
Rate Coefficients ◽  
Quantum Scattering ◽  
Final States ◽  
Energy Gap Law ◽  
Quantitative Basis

Abstract Inelastic collisions involving molecular species are key to energy transfer in gaseous environments. They are commonly governed by an energy gap law, which dictates that transitions are dominated by those between initial and final states with roughly the same ro-vibrational energy. Transitions involving rotational inelasticity are often further constrained by the rotational angular momentum. Here, we demonstrate using full-dimensional quantum scattering on an ab initio based global potential energy surface (PES) that HF–HF inelastic collisions do not obey the energy and angular momentum gap laws. Detailed analyses attribute the failure of gap laws to the exceedingly strong intermolecular interaction. On the other hand, vibrational state-resolved rate coefficients are in good agreement with existing experimental results, validating the accuracy of the PES. These new and surprising results are expected to extend our understanding of energy transfer and provide a quantitative basis for numerical simulations of hydrogen fluoride chemical lasers.

Rotational cross sections and rate coefficients of CP ( X 2 Σ + ) $\mathrm{CP}(\mathrm{X}^{2}\varSigma ^{+})$ induced by its collision with He ( 1 S ) $\mathrm{He}(^{1}S)$ at low temperature

2018 ◽  
Vol 363 (3) ◽  
Author(s):  
Théophile Tchakoua ◽  
Mama Pamboundom ◽  
Berthelot Said Duvalier Ramlina Vamhindi ◽  
Serge Guy Nana Engo ◽  
Ousmanou Motapon ◽  
...  
Keyword(s):  
Low Temperature ◽  
Cross Sections ◽  
Rate Coefficients

Inelastic rate coefficients for collisions of C4H− with H2

2021 ◽  
Author(s):  
Christian Balança ◽  
Ernesto Quintas-Sánchez ◽  
Richard Dawes ◽  
Fabien Dumouchel ◽  
François Lique ◽  
...  
Keyword(s):  
Cross Sections ◽  
Rotational Level ◽  
Carbon Chain ◽  
Rate Coefficients ◽  
Thermodynamical Equilibrium ◽  
Close Coupling ◽  
State Approximation ◽  
Explicitly Correlated ◽  
State Rate ◽  
Chemical Conditions

Abstract Carbon-chain anions were recently detected in the interstellar medium. These very reactive species are used as tracers of the physical and chemical conditions in a variety of astrophysical environments. However, the Local Thermodynamical Equilibrium conditions are generally not fulfilled in these environments. Therefore, collisional as well as radiative rates are needed to accurately model the observed emission lines. We determine in this work the state-to-state rate coefficients of C4H− in collision with both ortho- and para-H2. A new ab initio 4D potential energy surface was computed using explicitly-correlated coupled cluster procedures. This surface was then employed to determine rotational excitation and de-excitation cross sections and rate coefficients for the first 21 rotational levels (up to rotational level j1 = 20) using the close-coupling method, while the coupled-state approximation was used to extend the calculations up to j1 = 30. State-to-state rate coefficients were obtained for the temperature range 2–100 K. The differences between the ortho- and para-H2 rate coefficients are found to be small.

Sign in / Sign up

Export Citation Format

Share Document