Abstract:
The atomic and molecular collision processes are of fundamental interest, which are crucial in several fields including cometary and interstellar matter, as well as the upper planetary atmosphere1. Such collisions lead to various elastic and inelastic processes. The major components of the stellar wind ions are H+, He+, He2+ along with minor neutrals such as CO, N2, O2, H2, NO, and so on. The current research aims to comprehend ion-diatom dynamics from the quantum as well as semi-classical viewpoints. Helium is observed to allow large number of product channels in the charge transfer process due to its high ionization potential value (24.5 eV). We present an ab initio analysis of the charge transfer reaction of He+ with N22. Various excited states of N2+ have been identified and are found to corroborate the collision spectra3. Our next study elaborates on the charge transfer reaction of He+ with CO molecule4. Various charge transfer channels have been identified, which are in agreement with the experimental findings5. Adiabatic potential energy surfaces with non-adiabatic coupling matrix elements (NACMEs) and quasi-diabatic potential energy surfaces along with the coupling potentials are also computed which can facilitate the dynamics study at various collision energies. Dynamics within the quantum (for moderate collision energy) and semiclassical (for high collision energy) formulations have been performed. We have studied IVE and VCT processes of H+ with CO at Ecoll = 30 eV within the vibrational close-coupling rotational infinite-order sudden approximation (VCC-RIOSA) and results have been compared with scattering experiments6. A systematic study has been done to see the involvement of excited states. Further investigations indicate that the dynamical attributes are sensitive to the quasi-diabatization procedure. Elastic and charge transfer dynamics of H+ + O2 have been carried out in high collision energy range (0.5 – 5 keV) using semi-classical time dependent impact parameter model. A good agreement is observed between the computed and the available experimental findings78.

References:
(1) Larsson, M. et. al., Reports Prog. Phys. 2012, 75 (6) 066901.
(2) Reja, D.; Kumar, S., ChemPhysChem 2023, e202200880.
(3) Dowek, D. et. al., Phys. Rev. A 1981, 24 (5), 2445–2464.
(4) Reja, D.; Kumar, S., Chem. Phys. Lett. 2023, 822, 140535.
(5) Dowek, D. et. al., Phys. Rev. A 1983, 28 (5), 2838–2850.
(6) Niedner‐Schatteburg, G.; Toennies, J. P., Proton Energy Loss Spectroscopy as a State‐to‐State Probe of Molecular Dynamics; 1992; Vol. LXXXII.
(7) Cabrera-Trujillo, R. et. al., Phys. Rev. A., 2004, 70 (4), 1–9.
(8) Gao, R. S. et. al., Phys. Rev. A., 1990, 41 (11), 5229-5933.