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We present calculated cross sections and rate coefficients for the formation of the dicarbon cation (C$_2^+$) by the radiative association process in collisions of a C$(^3P)$ atom and a C$^+(^2P^o)$ ion. Molecular structure calculations for…

Atomic Physics · Physics 2019-10-24 James F. Babb , R. T. Smyth , B. M. McLaughlin

In the present paper the problem of the radiative association of atoms of carbon C with electrons $e^{-}$ for kinetic temperatures $T_{c}$ of $100 < T_{c} < 3000$ K is considered. The calculation of the rate rate constant of the radiative…

Astrophysics · Physics 2007-05-23 J. Campos , A. Lipovka , J. Saucedo

A theoretical rate constant for the associative detachment reaction Rb($^{2}S$)$+$OH$^{-}$($^{1}\Sigma^{+}$)$\rightarrow \,$ RbOH($^{1}\Sigma^{+}$)$+\,e^{-}$ of 4$\,\times$10$^{-10}$cm$^{3}$s$^{-1}$ at 300 K has been calculated. This result…

Chemical Physics · Physics 2016-06-22 Milaim Kas , Jérôme Loreau , Jacques Liévin , Nathalie Vaeck

Our current understanding of interstellar carbon fractionation hinges on the interpretation of astrochemical kinetic models. Yet, the various reactions included carry large uncertainties in their (estimated) rate coefficients, notably those…

Astrophysics of Galaxies · Physics 2021-03-24 C. M. R. Rocha , H. Linnartz

Cross sections and rate coefficients for rovibronic excitation of the CH$^+$ ion by electron impact and dissociative recombination of CH$^+$ with electrons are evaluated using a theoretical approach combining an R-matrix method and…

Astrophysics of Galaxies · Physics 2025-11-25 Joshua Forer , Dávid Hvizdoš , Mehdi Ayouz , Chris H. Greene , Viatcheslav Kokoouline

We propose an efficient method to compute reaction rate constants of thermally activated processes occurring in many-body systems at finite temperature. The method consists in two steps: first, paths are sampled using a transition path…

Statistical Mechanics · Physics 2011-12-22 Massimiliano Picciani

Canonical instanton theory is known to overestimate the rate constant close to a system-dependent crossover temperature and is inapplicable above that temperature. We compare the accuracy of the reaction rate constants calculated using…

Chemical Physics · Physics 2020-09-15 Sean McConnell , Johannes Kästner

We present theoretical thermally-averaged rate constants for vibrational and rotational (de-)excitation of the H3+ ion by electron impact. The constants are calculated using the multi-channel quantum-defect approach. The calculation…

Atomic Physics · Physics 2015-05-18 Viatcheslav Kokoouline , Alexandre Faure , Jonathan Tennyson , Chris H. Greene

Light-assisted reactive collisions between laser-cooled Ba+ ions and Rb atoms were studied in an ion-atom hybrid trap. The reaction rate was found to strongly depend on the electronic state of the reaction partners with the largest rate…

Atomic Physics · Physics 2015-06-12 Felix H. J. Hall , Mireille Aymar , Maurice Raoult , Olivier Dulieu , Stefan Willitsch

The temperature dependence of the rate of the reaction CH_4+H \to CH_3+H_2 is studied using classical collision theory with a temperature-dependent effective potential derived from a path integral analysis. Analytical expressions are…

Chemical Physics · Physics 2016-09-08 David Z. Goodson , Dustin W. Roelse , Wan-Ting Chiang , Steven M. Valone , J. D. Doll

Our knowledge about the "cold" Universe often relies on molecular spectra. A general property of such spectra is that the energy level populations are rarely at local thermodynamic equilibrium. Solving the radiative transfer thus requires…

Instrumentation and Methods for Astrophysics · Physics 2018-01-23 Jérôme Loreau , François Lique , Alexandre Faure

A theoretical method for the estimation of cross sections and rates for excitation and charge transfer processes in low-energy hydrogen atom collisions with neutral atoms, based on an asymptotic two-electron model of ionic-covalent…

Atomic Physics · Physics 2016-05-04 Paul S. Barklem

Detailed quantum chemistry calculations within the multireference configuration interaction approximation with the Davidson correction (MRCI+Q) are presented using an aug-cc-pV6Z basis set, for the potential energy curves and transition…

Atomic Physics · Physics 2016-09-08 Robert C. Forrey , James F. Babb , Phillip C. Stancil , Brendan M. McLaughlin

The experimental determination of the reaction rate coefficients for production and destruction of $\text{HCN}^+$ and $\text{HNC}^+$ in collisions with $\text{H}_2$ is presented. A variable temperature 22 pole radio frequency ion trap was…

Astrophysics of Galaxies · Physics 2023-06-08 Petr Dohnal , Pavol Jusko , Miguel Jiménez-Redondo , Paola Caselli

The dynamics of the reaction H + OH $\to$ O (3P) + H2 have been studied in a series of quasi-classical trajectory (QCT) calculations and transition state theory (TST) methods using high quality 3A' and 3A'' potential energy surfaces (PESs).…

Solar and Stellar Astrophysics · Physics 2014-02-27 Xiaohu Li , Carina Arasa , Marc C. van Hemert , Ewine F. van Dishoeck

A general method for the direct evaluation of the temperature dependence of the quantum-mechanical reaction rate constant in many-dimensional systems is described. The method is based on the quantum instanton approximation for the rate…

Chemical Physics · Physics 2013-01-15 Marcin Buchowiecki , Jiri Vanicek

Accurate molecular data for the low-lying states of SiO are computed and used to calculate rate constants for radiative association of Si and O. Einstein A-coefficients are also calculated for transitions between all of the bound and…

Instrumentation and Methods for Astrophysics · Physics 2017-08-23 M. Cairnie , R. C. Forrey , J. F. Babb , P. C. Stancil , B. M. McLaughlin

Modern potential energy surfaces have shifted attention to molecular simulations of chemical reactions. While various methods can estimate rate constants for conformational transitions in molecular dynamics simulations, their applicability…

Chemical Physics · Physics 2024-07-10 Simon Ghysbrecht , Luca Donati , Bettina G. Keller

Modeling environments that are not in local thermal equilibrium, such as protoplanetary disks or planetary atmospheres, with molecular spectroscopic data from space telescopes requires knowledge of the rate coefficients of rovibrationally…

Atomic Physics · Physics 2023-10-10 Taha Selim , Ad van der Avoird , Gerrit C. Groenenboom

We have incorporated our experimentally derived thermal rate coefficients for C + H$_3^+$ forming CH$^+$ and CH$_2^+$ into a commonly used astrochemical model. We find that the Arrhenius-Kooij equation typically used in chemical models does…

Instrumentation and Methods for Astrophysics · Physics 2016-11-23 S. Vissapragada , C. F. Buzard , K. A. Miller , A. P. O'Connor , N. de Ruette , X. Urbain , D. W. Savin
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