Step Towards Modeling the Atmosphere of Titan: State-Selected Reactions of O+ with Methane

0459443 - ÚFCH JH 2017 RIV DE eng J - Journal Article
Hrušák, Jan - Paidarová, Ivana
Step Towards Modeling the Atmosphere of Titan: State-Selected Reactions of O+ with Methane.
Origins of Life and Evolution of the Biosphere. Roč. 46, č. 4 (2016), s. 419-424. ISSN 0169-6149. E-ISSN 1573-0875
Grant - others:COST(XE) TD1308
Institutional support: RVO:61388955
Keywords : methane oxidation * excited states * transition dipole moments
Subject RIV: CF - Physical ; Theoretical Chemistry
Impact factor: 1.000, year: 2016

Methane conversion and in particular the formation of the C-O bond is one of fundamental entries to organic chemistry and it appears to be essential for understanding parts of atmospheric chemistry of Titan, but, in broader terms it might be also relevant for Earth-like exoplanets. Theoretical study of the reactions of methane with atomic oxygen ion in its excited electronic states requires treating simultaneously at least 19 electronic states. Development of a computational strategy that would allow chemically reasonable and computationally feasible treatment of the CH4 (X)/O+ (2D, 2P) system is by far not trivial and it requires careful examination of all the complex features of the corresponding 19 potential energy surfaces. Before entering the discussion of the rich (photo) chemistry, inspection of the long range behavior of the system with focus on electric dipole transition moments is required. Our calculations show nonzero probability for the reactants to decay before entering the multiple avoided crossings region of the [CH4 + O → products]+ reaction. For the CH4/O+ (2P) system non-zero transition moment probabilities occur over the entire range of considered C-O distances (up to 15 Å), while for the CH4/O+ (2D) system these probabilities are lower by one order of magnitude and were found only at C-O distances smaller than 6 Å.
Permanent Link: http://hdl.handle.net/11104/0259637