Reactive collision of electrons with CO⁺ in cometary coma

Abstract

Context. In order to improve our understanding of the kinetics of the cometary coma, theoretical studies of the major reactive collisions in these environments are needed. Deep in the collisional coma, inelastic collisions between thermal electrons and molecular ions result in recombination and vibrational excitation, the rates of these processes being particularly elevated due to the high charged particle densities in the inner region. Aims. This work addresses the dissociative recombination, vibrational excitation, and vibrational de-excitation of electrons with CO + molecular cations. The aim of this study is to understand the importance of these reactive collisions in producing carbon and oxygen atoms in cometary activity. Methods. The cross-section calculations were based on Multichannel Quantum Defect Theory. The molecular data sets, used here to take into account the nuclear dynamics, were based on ab initio R-matrix approach. Results. The cross sections for the dissociative recombination, vibrational excitation, and vibrational de-excitation processes, for the six lowest vibrational levels of CO + -relevant for the electronic temperatures observed in comets -are computed, as well as their corresponding Maxwell rate coefficients. Moreover, final state distributions for different dissociation pathways are presented. Conclusions. Among all reactive collisions taking place between low-energy electrons and CO + , the dissociative recombination is the most important process at electronic temperatures characterizing the comets. We have shown that this process can be a major source of O( 3 P), O( 1 D), O( 1 S), C( 3 P) and C( 1 D) produced in the cometary coma at small cometocentric distances.

Reactive collisions between electrons and BeT$^+$: Complete set of thermal rate coefficients up to 5000 K

“…(1)(2)(3). Along with other methods we use [28], MQDT has proven to be a powerful and successful method when applied to several diatomic systems like H + 2 [29], N + 2 [30], CO + [31]. This approach, combined with the R-matrix technique, was also used to model satisfactorily -although less accurately -electronic collisions with poly-atomic ions like BF + 2 [32] and NH 2 CH 2 O + [34].…”

Plasma Modeling and Prebiotic Chemistry: A Review of the State-of-the-Art and Perspectives

“…In recent years, motivated by the great importance of CO, CO , CO and NO molecules in astrophysics, aerospace and laser technologies, great improvements, theoretically and experimentally, in the quantitative understanding of the reactivity of these species in a weakly-ionized plasma have been achieved. Figure 8 summarizes the results for cross sections by electron impact for CO [ 100 , 101 ] and NO [ 102 , 103 ] molecules obtained with the LCP method, for CO [ 104 ] molecular ion obtained in the MQDT framework and for experimental data for the CO molecule [ 105 ].…”

“… Compilation of state-resolved cross sections by electron-impact: ( a ) electron-CO [ 100 , 101 ]; ( b ) electron-CO [ 105 ]; ( c ) electron-CO [ 104 ]; ( d ) electron-NO [ 102 , 103 ]. Processes of: Vibrational Excitation (VE); Dissociative Attachment (DA); Dissociative Recombination (DR); Dissociative Excitation (DE).…”

Electron-Induced Excitation, Recombination, and Dissociation of Molecular Ions Initiating the Formation of Complex Organic Molecules

“…A detailed description of our theoretical approach has been given in previous studies on different diatomic systems, including the carbon-containing ones. − The main ideas and steps are recalled below for the three standard situations (a, b, and c) encountered. This is performed in the order of the accuracy in predicting the cross-section, from the very fine modeling of the rotational (a) and/or vibrational (a, b) resonances associated with the temporary capture into singly excited Rydberg states, to that of the broad resonances associated with the capture into doubly excited states (c).…”

“…The structure of the interaction matrix in block form, more complex than that in case b. Equation , is, e.g., for the case of one ground bound electronic core and two excited bound electronic cores the following: where the collective indices d̅ , v̅ c i , i = 1, 2, 3, span the ensembles of all individual indices connected to the dissociation channels and ionization channels built on c 1 (ground), c 2 , and c 3 (excited) ion cores. − …”