Rotational State-to-State Rate Coefficients of HeHNe⁺ by Collision with He at Low Temperatures

Abstract

The HeHNe+ molecule is expected to have, after NeH+, the strongest neon bond found so far. Furthermore, formation mechanisms in the interstellar medium (ISM) have been proposed for this molecule. If HeHNe+ is detected, the collisional rate coefficients of this species with the most abundant constituents of the ISM will be critical for employing nonlocal thermodynamic equilibrium (non-LTE) models. Therefore, the main goals of this work are to study the interaction of HeHNe+ with He and to report a set of rotational rate coefficients for this collision at low temperatures. For this purpose, the first potential energy surface for the HeHNe+ + He complex is developed from ab initio calculations. The close-coupling method is employed for studying the dynamics of the system. A |Δj| = 2 propensity rule is found for transitions starting from the rotational state j = 5. Finally, the rate coefficients for the lower 20 rotational states of HeHNe+ are reported.

Noble gas hydrides: theoretical prediction of the first group of anionic species

“…The first evidence of gaseous cationic species dates back to 1925, 1 when Hogness and Lunn detected the simplest HeH + and HeH 2 + from ionized He/H 2 mixtures. Over the years, the gas-phase chemistry of the Ng m H n + (Ng = He–Xe; m , n ≥ 1) turned out to be rich and varied, 2 and the rejuvenated interest that it is currently enjoying 3–13 is also stimulated by the actual detection of ArH + and HeH + in various galactic and extragalactic regions. 14–18 Neutral compounds with Ng–H bonds emerged first in 1995, 19 when Räsänen and his coworkers identified the strong infrared absorbers originating from the photodissociation of hydrogen halides in Kr and Xe matrices as the “inserted” compounds HXeI, HXeBr, HXeCl, and HKrCl.…”

Unusual Dynamics and Vibrational Fingerprints of van der Waals Dimers Formed by Linear Molecules and Rare-Gas Atoms

“…86 The He-solvated dimers, such as HHe 3 + , HNe 2 + •He, HAr 2 + •He, and HHeNe + •He, have also been playing a crucial role in testing collisional and nonlocal thermodynamic equilibrium models. 87,88 A common structural motif of the four proton-bound rare-gas dimers mentioned is that their chromophores are triatomic, formally linear cations. If a linear molecule, whose quadrupole moment dominates its multipole expansion, 89 interacts with a single solvating atom, the resulting dimer forms a (nearly) T-shaped global minimum (GM), though linear secondary minima (SM) might also be present on the potential energy surface (PES).…”

“…The structures and vibrations of larger HAr n + complexes ( n = 3–7) have also been studied via gas-phase infrared spectroscopy . The He-solvated dimers, such as HHe 3 + , HNe 2 + ·He, HAr 2 + ·He, and HHeNe + ·He, have also been playing a crucial role in testing collisional and nonlocal thermodynamic equilibrium models. , A common structural motif of the four proton-bound rare-gas dimers mentioned is that their chromophores are triatomic, formally linear cations.…”