Comparisons and scaling rules between N+N₂and N₂+N₂collision induced dissociation cross sections from atomistic studies

Abstract

Quantitative knowledge of elementary processes involved in plasmas are key to successfully perform accurate kinetic simulations. The issue is the huge amount of data to treat, both in the dynamical calculation and in the kinetic simulation. The aim of this paper is to study the dissociation in atom-molecule (AM) and molecule-molecule (MM) collisions involving nitrogen, obtained by molecular dynamics calculations considering vibrational states in the range 10-50 and collision energy up to 10eV, in order to formulate suitable scaling laws resulting in less expensive computational procedures and easier to handle treatments in kinetic simulations. It is shown that, while a direct substitution of MM dissociation cross sections with AM ones might be acceptable only at very high collision energy, scaling laws application allows to obtain quite good results on almost the whole energy range of interest.

Collisional O2+ N2State-Selected Cross Sections for Open Science Cloud Reuse

“…This also offers the advantage of both dealing on an even foot all paths and structures of the process channel and binding the key PES features to the focused process evolution when branching into different channels. As a matter of fact, when moving along an increasing value of α (from α = 0 to α = 90°), the corresponding values of the PES (at the appropriate values of ρ) agree with the threshold energy values even by assuming simple interaction models and internal energy shifts …”

“…These threshold energy values tell us that a total energy of roughly 165, 137, and 123 kcal mol –1 for v = 10, 20, and 30, respectively, is needed to dissociate the oxygen molecule (120.2 kcal mol –1 ), and this feature clearly demonstrates the lower efficiency of E tr with respect to the rovibrational energy in promoting dissociation. As shown in ref , all these features turn out to be useful for modeling the cross section using reduced dimensionality approaches built over crossed molecular beam experiments (see also refs and ).…”

“…As a matter of fact, when moving along an increasing value of α (from α = 0 to α = 90°), the corresponding values of the PES (at the appropriate values of ρ) agree with the threshold energy values even by assuming simple interaction models and internal energy shifts. 31 3.3. Key Features of the Cross Section for O 2 (v,j) + N 2 (w = 0,m = 0) Collisions.…”

“…More in detail, in the present paper, we compare for the title reaction the vibrational state-selected and rotational state thermalized rate coefficients with those derived from fully discretized internal energy cross sections by supporting the analysis of related components with both internuclear distance and bond-order (BO, by analogy with the Pauling’s homonym concept) reduced dimensionality representations of the isoenergetic contours of the PES as well as of the homonymous process coordinate. Such procedure is inspired by the guidelines given in ref and by the applications of refs − to N + N 2 , O + O 2 , O + N 2 , N 2 + N 2 , and O 2 + N 2 systems at different values of the translational energy E tr for a selected set of rovibrational energy combinations. The outcomes of such calculations were then used, for example, for Monte Carlo simulation schemes and accurate calibration of the N 2 –N 2 PES …”

The role of the long-range tail of the potential in O2 + N2 collisional inelastic vibrational energy transfers

“…24,25 This method makes internally consistent the for mulation of two, three and four body components of the interac tion and has the advantage of providing a valid description of the collision induced fragmentation of the involved molecules. 6,26 In the progress of our studies aimed at characterizing the non reactive diatomdiatom behaviour of O 2 + N 2 collisions, we first started using an older semiempirical PES (GB1) 27 , and we moved later to the more recently formulated semiempirical PESs MF1 and MF2. 12,13 In particular, Quantum Classical (QC) values com puted on MF1 12 agreed with measured vibrationto vibration (VV) and vibrationtotranslation (VT) rate coefficients 28 and with VV rate coefficients for transitions involving the lowest vibra tional states.…”