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Titolo:
Reductive activation of the nitrogen molecule at the surface of "electron-rich" MgO and CaO. The N-2(-) surface adsorbed radical ion
Autore:
Chiesa, M; Giamello, E; Murphy, DM; Pacchioni, G; Paganini, MC; Soave, R; Sojka, Z;
Indirizzi:
Univ Turin, Dipartimento Chim IFM, I-10125 Turin, Italy Univ Turin TurinItaly I-10125 partimento Chim IFM, I-10125 Turin, Italy Unita INFM Torino, I-10125 Turin, Italy Unita INFM Torino Turin Italy I-10125 INFM Torino, I-10125 Turin, Italy Univ Milan, Dipartimento Sci Mat, I-20125 Milan, Italy Univ Milan Milan Italy I-20125 ipartimento Sci Mat, I-20125 Milan, Italy Unita INFM Milano, I-20125 Milan, Italy Unita INFM Milano Milan Italy I-20125 INFM Milano, I-20125 Milan, Italy Univ Wales Coll Cardiff, Dept Chem, Cardiff CF10 3TB, S Glam, Wales Univ Wales Coll Cardiff Cardiff S Glam Wales CF10 3TB 3TB, S Glam, Wales Jagiellonian Univ, Dept Chem, Krakow, Poland Jagiellonian Univ Krakow Poland llonian Univ, Dept Chem, Krakow, Poland
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY B
fascicolo: 2, volume: 105, anno: 2001,
pagine: 497 - 505
SICI:
1520-6106(20010118)105:2<497:RAOTNM>2.0.ZU;2-V
Fonte:
ISI
Lingua:
ENG
Soggetto:
DOPED MAGNESIUM-OXIDE; MGO(100) SURFACE; EMBEDDED-CLUSTER; SUPEROXIDE IONS; COLOR-CENTERS; DEFECT SITES; CO; ADSORPTION; RESONANCE; EPR;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
52
Recensione:
Indirizzi per estratti:
Indirizzo: Giamello, E Univ Turin, Dipartimento Chim IFM, Via Giuria 7, I-10125 Turin, Italy Univ Turin Via Giuria 7 Turin Italy I-10125 0125 Turin, Italy
Citazione:
M. Chiesa et al., "Reductive activation of the nitrogen molecule at the surface of "electron-rich" MgO and CaO. The N-2(-) surface adsorbed radical ion", J PHYS CH B, 105(2), 2001, pp. 497-505

Abstract

Upon nitrogen adsorption at low temperature onto the surface of magnesium oxide and calcium oxide containing F-S(+) centers (single electron trapped in a suitable surface vacancy), electron transfer occurs from the solid to the adsorbed molecule. About 90% of the total electron density is localizedon the adsorbed molecule. The Ii-electron N-2(-) radical anion so formed has been detected by electron paramagnetic resonance for both N-14(2) and N-15(2). The electron transfer is reversible and, when the pressure is lowered or the temperature increased, the Nz molecules desorb, regenerating the original F-S(+) center. The diatomic radical ion lies parallel to the surface, and the electron density is mainly confined in the pi (y)* orbital. Theoretical calculations at the DFT level indicate that a small energy barrier separates the unbound F-S(+)/N-2 state from the bound F-S(2+)/N-2(-) state. This explains the facile reversibility of the electron-transfer process. The calculated spin densities are in excellent agreement with those derived from the experiments. The results reported in this paper represent a new method for N-2 activation over the basic alkaline earth oxides, which are also known to activate H-2 by dissociative adsorption.

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Documento generato il 25/09/20 alle ore 22:53:13