Speaker
Description
Electron impact recombination, (ro-)vibrational-, electronic- and dissociative excitation
of molecular cations: $AB^++e^− \rightarrow AB^*, AB^{**} \rightarrow A + B$ (DR) or ${AB^+}^* + e^−$ (RV(d)E) or $A + B^+ + e^−$ (DE) are in the heart of the molecular reactivity in all cold ionized media [1], being major charged particles destruction reactions and producing often atomic species in metastable states, inaccessible through optical excitations. They involve super-excited molecular states undergoing predissociation and autoionization, having thus strong resonant character. The Multichannel Quantum Defect Theory (MQDT) [1,2] based methods are the most suitable approaches for these processes, capable to account the strong mixing between ionization and dissociative channels, open - direct mechanism - and closed - indirect mechanism, via capture into prominent Rydberg resonances correlating to the ground and excited ionic states, and the rotational effects. These features will be illustrated for several cations of high astrophysical, planetary atmosphere and fusion edge plasma relevance such as SH$^+$ [3], NS$^+$ [4] and BeH$^+$ [5], comparisons with other existing theoretical and experimental results also being performed. Advancement in the theoretical treatment - different dissociation channels or the isotopic effects for diatomic and polyatomic systems like NeH$^+$ [6], H$_2^+$/HD$^+$ and N$_2$H$^+$ [7], or C$_2$H$^+$ etc. - will be presented.
[1] I. F. Schneider, O. Dulieu, J. Robert, eds., EPJ Web of Conferences 84 (2015).
[2] J. Zs. Mezei etal, ACS Earth and Space Chem 3, 2276 (2019).
[3] J. Boffelli etal, MNRAS 522, 2259 (2023).
[4] R. Hassaine etal, J. Phys. B: At. Mol. Opt. Phys. 57, 165201 (2024).
[5] E. Djuissi etal, PCCP 26, 18311 (2024).
[6] R. Hassaine etal, J. Chem. Phys. 162, 134302 (2025).
[7] J. Zs. Mezei etal, EPJST 232, 1967 (2023).
