The eMol (Electron/MOLecule collisions) group is centred at Laboratoire Ondes et Milieux Complexes (LOMC UMR6294), a French laboratory affiliated to Université Le Havre Normandie (ULHN) and to the Centre National de la Recherche Scientifique (CNRS). Meanwhile, this group is an international one, since the researchers from Le Havre work often together with colleagues from Institute for Nuclear Research in Debrecen (Hungary), Scottish Church College in Calcutta (India), Politehnica and West Universities in Timisoara (Romania), Douala and Maroua Universities (Cameroon) and Burundi University.
Furthermore, we have strong collaborations with University College London (UK), Université Paris-Saclay (France), University of Central Florida, Orlando (US) and Istituto per la Scienza e Tecnologia dei Plasmi, Bari (Italy).
Our main research activity concerns the theoretical study of the reactive collisions of electrons with molecular positive ions (cations): dissociative recombination, ro-vibrational (de)excitation and dissociative excitation.
These elementary processes are in the heart of molecular reactivity of the cold ionised media [2], being major charged particles destruction factors. They involve super-excited molecular states undergoing pre-dissociation and auto-ionization and having thus strong resonant character. Consequently, they are modelled in a beyond-Born-Oppenheimer formalism and, very often, require rather quasi-diabatic than adiabatic representations of the molecular states. In addition, they involve particularly sophisticated methods for modelling the collisional dynamics, able to manage superposition of many continua and infinite series of Rydberg states. We use the Multichannel Quantum Defect Theory [1, 3-8], 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 ground and excited ionic states, and the rotational effects.
We employ our theoretical tools in order to produce cross sections and rate coefficients ready to be used in the collisional-radiative models for astro-chemistry – interstellar molecular clouds, early universe [1, 9] – and of several types of cold plasmas – close to the wall of the fusion devices (JET, ITER, etc.) [10, 11], at the boundary layer of space-crafts during their entries in the planetary atmospheres [12,13], and other plasmas of industrial or energetic interest [14].
Contact
Ioan F. SCHNEIDER
Université Le Havre Normandie, UFR Sciences & Techniques, 25, rue Philippe Lebon, BP 1123, 76063 Le Havre cedex, France Email: ioan.schneider@univ-lehavre.fr Phone: +33 (0)6 61 50 53 99
References
[1] D. O. Kashinski et al., "A theoretical study of the dissociative recombination of SH with electrons through the 2Π states of SH", The Journal of Chemical Physics146, 204109 (2017). [link to article]
[2] I. F. Schneider, O. Dulieu and J. Robert (editors), "DR2013: Ninth International Conference on Dissociative Recombination: Theory, Experiment, and Applications", EPJ Web of Conferences84 (2015).
[3] Ch. Jungen, "Elements of quantum defect theory", Handbook of High Resolution Spectroscopy, 471 (2011).
[4] A. Giusti, "A multichannel quantum defect approach to dissociative recombination", Journal of Physics B: Atomic and Molecular Physics13, 3867-3894 (1980). [link to article]
[5] I. F. Schneider, O. Dulieu and A. Giusti-Suzor, "The role of Rydberg states in H2+ dissociative recombination with slow electrons", Journal of Physics B: Atomic, Molecular and Optical Physics24, L289 . [link to article]
[6] F. O. Waffeu Tamo et al., "Assignment of resonances in dissociative recombination of HD+ ions: High-resolution measurements compared with accurate computations", Physical Review A64, 022710 (2011). [link to article]
[7] K. Chakrabarti et al., "Dissociative recombination of electrons with diatomic molecular cations above dissociation threshold: Application to H2+ and HD+", Physical Review A87, 022702 (2013). [link to article]
[8] O. Motapon et al., "Rotational transitions induced by collisions of HD+ ions with low-energy electrons", Physical Review A90, 012706 (2014). [link to article]
[9] Z. J. Mezei et al., "Electron-Induced Excitation, Recombination, and Dissociation of Molecular Ions Initiating the Formation of Complex Organic Molecules", ACS Earth and Space Chemistry3, 2376-2389 (2019). [link to article]
[10] S. Niyonzima et al., "Low-energy collisions between electrons and BeD+", Plasma Sources Science and Technology27, 025015 (2018). [link to article]
[11] N. Pop et al., "Reactive collisions between electrons and BeT+: Complete set of thermal rate coefficients up to 5000 K", Atomic Data and Nuclear Data Tables139, 101414 (2021). [link to article]
[12] A. Bultel et al., "Collisional-radiative model in air for earth re-entry problems", Physics of Plasmas13, 043502 (2006). [link to article]
[13] A. Abdoulanziz et al., "Low-energy electron impact dissociative recombination and vibrational transitions of N2+", Journal of Applied Physics129, 053303 (2021). [link to article]
[14] J. Zs Mezei et al., "Dissociative recombination and vibrational excitation of BF+in low energy electron collisions", Plasma Sources Science and Technology25, 055022 (2016). [link to article]