title: Ferroelectric triggering of carbon monoxide adsorption on lead zirco-titanate (001) surfaces.
abstract: Atomically clean lead zirco-titanate PbZr0.2Ti0.8O3(001) layers exhibit a polarization oriented inwards P(-), visible by a band bending of all core levels towards lower binding energies, whereas as introduced layers exhibit P(+)polarization under air or in ultrahigh vacuum. The magnitude of the inwards polarization decreases when the temperature is increased at 700 K. CO adsorption on P(-)polarized surfaces saturates at about one quarter of a monolayer of carbon, and occurs in both molecular (oxidized) and dissociated (reduced) states of carbon, with a large majority of reduced state. The sticking of CO on the surface in ultrahigh vacuum is found to be directly related to the P(-)polarization state of the surface. A simple electrostatic mechanism is proposed to explain these dissociation processes and the sticking of carbon on P(-)polarized areas. Carbon desorbs also when the surface is irradiated with soft X-rays. Carbon desorption when the polarization is lost proceeds most probably in form of CO2. Upon carbon desorption cycles, the ferroelectric surface is depleted in oxygen and at some point reverses its polarization, owing to electrons provided by oxygen vacancies which are able to screen the depolarization field produced by positive fixed charges at the surface.
authors.affiliation: National Institute of Materials Physics, Atomistilor 405A, 077125 Măgurele-Ilfov, Romania.|University of Bucharest, Faculty of Physics, Atomiştilor 405, 077125 Măgurele-Ilfov, Romania.
authors.forename: Liviu Cristian
authors.initials: LC
authors.lastname: Tănase
authors.affiliation: National Institute of Materials Physics, Atomistilor 405A, 077125 Măgurele-Ilfov, Romania.
authors.forename: Nicoleta Georgiana
authors.initials: NG
authors.lastname: Apostol
authors.affiliation: National Institute of Materials Physics, Atomistilor 405A, 077125 Măgurele-Ilfov, Romania.|University of Bucharest, Faculty of Physics, Atomiştilor 405, 077125 Măgurele-Ilfov, Romania.
authors.forename: Laura Elena
authors.initials: LE
authors.lastname: Abramiuc
authors.affiliation: National Institute of Materials Physics, Atomistilor 405A, 077125 Măgurele-Ilfov, Romania.|University of Trieste, Department of Physics, Via Valerio 2 - 34127 Trieste, Italy.
authors.forename: Cristian Alexandru
authors.initials: CA
authors.lastname: Tache
authors.affiliation: National Institute of Materials Physics, Atomistilor 405A, 077125 Măgurele-Ilfov, Romania.
authors.forename: Luminița
authors.initials: L
authors.lastname: Hrib
authors.affiliation: National Institute of Materials Physics, Atomistilor 405A, 077125 Măgurele-Ilfov, Romania.
authors.forename: Lucian
authors.initials: L
authors.lastname: Trupină
authors.affiliation: National Institute of Materials Physics, Atomistilor 405A, 077125 Măgurele-Ilfov, Romania.
authors.forename: Lucian
authors.initials: L
authors.lastname: Pintilie
authors.affiliation: National Institute of Materials Physics, Atomistilor 405A, 077125 Măgurele-Ilfov, Romania.
authors.forename: Cristian Mihail
authors.initials: CM
authors.lastname: Teodorescu