Ultra-thin oxide films grown on a metal substrate and of thickness smaller than 1 nm may exhibit unusual properties with respect to thicker films or single crystal oxide surfaces. In a previous study [G. Pacchioni, L. Giordano and M. Baistrocchi, Phys. Rev. Lett., 2005, 94, 226104] we have suggested that a Au atom adsorbed on a MgO/Mo(100) thin film becomes negatively charged by direct electron tunneling from the Mo metal and that this is related to the low MgO/Mo(100) work function. Here we show, based on periodic DFT supercell calculations, that charge transfer can occur also in the opposite direction by adsorption of electropositive K atoms on MgO/Ag(100) films. We predict the occurrence of a charge transfer also for Au on MgO/Ag(100)films despite the fact that here the work function is 1 eV larger than in MgO/Mo(100). The formation of a layer of adsorbed negative (Au delta-/MgO/Ag) or positive ((delta)(K)/MgO/Ag) adsorbates results in an increase or decrease, respectively, of the MgO/Ag(100) work function as predicted by the classical Gurney model for ionic adsorbates on metal surfaces.

Giordano, L., Pacchioni, G. (2006). Charge transfers at metal/oxide interfaces: a DFT study of formation of K delta and Au delta- species on MgO/Ag(100) ultra-thin films from deposition of neutral atoms. PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 8(28), 3335-3341 [10.1039/b604288k].

Charge transfers at metal/oxide interfaces: a DFT study of formation of K delta and Au delta- species on MgO/Ag(100) ultra-thin films from deposition of neutral atoms

GIORDANO, LIVIA;PACCHIONI, GIANFRANCO
2006

Abstract

Ultra-thin oxide films grown on a metal substrate and of thickness smaller than 1 nm may exhibit unusual properties with respect to thicker films or single crystal oxide surfaces. In a previous study [G. Pacchioni, L. Giordano and M. Baistrocchi, Phys. Rev. Lett., 2005, 94, 226104] we have suggested that a Au atom adsorbed on a MgO/Mo(100) thin film becomes negatively charged by direct electron tunneling from the Mo metal and that this is related to the low MgO/Mo(100) work function. Here we show, based on periodic DFT supercell calculations, that charge transfer can occur also in the opposite direction by adsorption of electropositive K atoms on MgO/Ag(100) films. We predict the occurrence of a charge transfer also for Au on MgO/Ag(100)films despite the fact that here the work function is 1 eV larger than in MgO/Mo(100). The formation of a layer of adsorbed negative (Au delta-/MgO/Ag) or positive ((delta)(K)/MgO/Ag) adsorbates results in an increase or decrease, respectively, of the MgO/Ag(100) work function as predicted by the classical Gurney model for ionic adsorbates on metal surfaces.
Articolo in rivista - Articolo scientifico
ultrathin films, DFT calculations
English
2006
8
28
3335
3341
none
Giordano, L., Pacchioni, G. (2006). Charge transfers at metal/oxide interfaces: a DFT study of formation of K delta and Au delta- species on MgO/Ag(100) ultra-thin films from deposition of neutral atoms. PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 8(28), 3335-3341 [10.1039/b604288k].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/21082
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