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The chemiionization reactions Ce+O and Ce+O2: assignment of the observed chemielectron bands

The chemiionization reactions Ce+O and Ce+O2: assignment of the observed chemielectron bands
The chemiionization reactions Ce+O and Ce+O2: assignment of the observed chemielectron bands
Multiconfigurational quantum chemical methods (CASSCF/CASPT2) have been used to study the chemiionization reactions Ce + O CeO+ + e- and Ce + O2 CeO + e-. Selected spectroscopic constants for CeOn and CeO (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 + O2(X3) and Ce + O2( a1g), the Ce + O2 CeO + 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 + O2 CeO + O, followed by Ce + O CeO+ + e-) as in the case of lanthanum. For Ce + O2 (a1g), a chemielectron band with higher kinetic energy than that recorded for Ce + O2( X3) is obtained. This is attributed to production of O( 1D) from the reaction Ce + O2( a1g) CeO + O( 1D), followed by chemiionization via the reaction Ce + O( 1D) 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.
cerium oxides, multiconfigurational methods, chemiionization reactions, spin-orbit coupling
0020-7608
2068-2079
Todorova, Tanya K.
de270f0a-1abc-4d7c-97f4-58a5d2860b23
Infante, Ivan
69c5436a-4746-4e1a-b9c9-65b06af14f03
Gagliardi, Laura
b20d2c29-eb23-4b27-bef0-9ea53ea717dc
Dyke, John M.
46393b45-6694-46f3-af20-d7369d26199f
Todorova, Tanya K.
de270f0a-1abc-4d7c-97f4-58a5d2860b23
Infante, Ivan
69c5436a-4746-4e1a-b9c9-65b06af14f03
Gagliardi, Laura
b20d2c29-eb23-4b27-bef0-9ea53ea717dc
Dyke, John M.
46393b45-6694-46f3-af20-d7369d26199f

Todorova, Tanya K., Infante, Ivan, Gagliardi, Laura and Dyke, John M. (2009) The chemiionization reactions Ce+O and Ce+O2: assignment of the observed chemielectron bands. International Journal of Quantum Chemistry, 109 (10), 2068-2079. (doi:10.1002/qua.22058).

Record type: Article

Abstract

Multiconfigurational quantum chemical methods (CASSCF/CASPT2) have been used to study the chemiionization reactions Ce + O CeO+ + e- and Ce + O2 CeO + e-. Selected spectroscopic constants for CeOn and CeO (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 + O2(X3) and Ce + O2( a1g), the Ce + O2 CeO + 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 + O2 CeO + O, followed by Ce + O CeO+ + e-) as in the case of lanthanum. For Ce + O2 (a1g), a chemielectron band with higher kinetic energy than that recorded for Ce + O2( X3) is obtained. This is attributed to production of O( 1D) from the reaction Ce + O2( a1g) CeO + O( 1D), followed by chemiionization via the reaction Ce + O( 1D) 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.

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Published date: March 2009
Keywords: cerium oxides, multiconfigurational methods, chemiionization reactions, spin-orbit coupling

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Local EPrints ID: 147169
URI: http://eprints.soton.ac.uk/id/eprint/147169
ISSN: 0020-7608
PURE UUID: d36dc90e-36bf-4f19-952e-01caddf7db87
ORCID for John M. Dyke: ORCID iD orcid.org/0000-0002-9808-303X

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Date deposited: 23 Apr 2010 11:36
Last modified: 03 Dec 2019 02:07

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