title: The reactivity of CO2 with K atoms adsorbed on MgO powders.
abstract: In this combined quantum chemical and EPR study we have investigated the formation of CO(2)(-) radicals by contact of CO(2) molecules with a K precovered MgO surface. K atoms have been deposited on polycrystalline MgO samples, and then exposed to CO(2). The typical EPR signal of the isolated K atoms disappears when the reaction with CO(2) takes place and a new paramagnetic species attributed to CO(2)(-) is observed. DFT cluster model calculations show that there is a spontaneous electron transfer from the adsorbed K atom to the CO(2) molecule, with formation of K(+)CO(2)(-) surface complexes. These species have the same electronic characteristics and spin distribution of gas-phase M(+)CO(2)(-) (M = Li, Na, K) molecules, but are stabilized by the presence of the ionic surface. The most stable MgO sites where the adsorption of CO(2) occurs and the computed EPR properties are discussed.
authors.affiliation: Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, 53-20125, Milano, Italy.
authors.forename: Gloria
authors.initials: G
authors.lastname: Preda
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Pacchioni
authors.forename: Mario
authors.initials: M
authors.lastname: Chiesa
authors.forename: Elio
authors.initials: E
authors.lastname: Giamello