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The chemiionization reactions Ce + O and Ce + O 2 : Assignment of the observed chemielectron bands
Author(s) -
Todorova Tanya K.,
Infante Ivan,
Gagliardi Laura,
Dyke John M.
Publication year - 2009
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.22058
Subject(s) - lanthanum , chemistry , exothermic reaction , kinetic energy , excited state , enthalpy , spectral line , analytical chemistry (journal) , atomic physics , inorganic chemistry , thermodynamics , physics , organic chemistry , quantum mechanics , astronomy , chromatography
Abstract Multiconfigurational quantum chemical methods (CASSCF/CASPT2) have been used to study the chemiionization reactions Ce + O → CeO + + e − and Ce + O 2 → CeO 2 ++ e − . Selected spectroscopic constants for CeO n and CeO n +( n = 1, 2), as well as reaction enthalpies of the chemiionization reactions of interest, have been computed and compared with experimental values. In contrast to the lanthanum case, for both Ce + O 2 (X 3 Σ g − ) and Ce + O 2 ( a 1 Δ g ), the Ce + O 2 → CeO 2 ++ e − reaction is shown to be exothermic, and thus, contributes to the experimental chemielectron spectra. The apparent discrepancy between the computed reaction enthalpies and the high kinetic energy offset values measured in the chemielectron spectra is rationalized by arguing that chemielectrons are produced mainly via two sequential reactions (Ce + O 2 → CeO + O, followed by Ce + O → CeO + + e − ) as in the case of lanthanum. For Ce + O 2 (a 1 Δ g ), a chemielectron band with higher kinetic energy than that recorded for Ce + O 2 ( X 3 Σ g − ) is obtained. This is attributed to production of O( 1 D) from the reaction Ce + O 2 ( a 1 Δ g ) → CeO + O( 1 D), followed by chemiionization via the reaction Ce + O( 1 D) → CeO + + e − . Accurate potential energy curves for the ground and a number of excited states of CeO and CeO + have been computed, and a mechanism for the chemiionization reactions investigated experimentally was proposed. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009