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Publication Detail
Exciton-Driven Highly Hyperthermal O-Atom Desorption from Nanostructured CaO
  • Publication Type:
    Journal article
  • Publication Sub Type:
    Article
  • Authors:
    Sushko PV, Shluger AL, Joly AG, Beck KM, Hess WP
  • Publisher:
    AMER CHEMICAL SOC
  • Publication date:
    27/01/2011
  • Pagination:
    692, 699
  • Journal:
    J PHYS CHEM C
  • Volume:
    115
  • Issue:
    3
  • Print ISSN:
    1932-7447
  • Language:
    EN
  • Keywords:
    EFFECTIVE CORE POTENTIALS, ALKALINE-EARTH OXIDES, CALCIUM-OXIDE, MOLECULAR CALCULATIONS, STIMULATED DESORPTION, SURFACE EXCITATION, IONIC SURFACES, ELECTRON TRAPS, MGO, CRYSTALS
  • Addresses:
    Hess, WP
    Pacific NW Natl Lab
    Chem & Mat Sci Div
    Environm Mol Sci Lab
    Richland
    WA
    99352
    USA

    UCL
    Dept Phys & Astron
    London
    WC1E 6BT
    England

    UCL
    London Ctr Nanotechnol
    London
    WC1E 6BT
    England
Abstract
We report qualitatively new highly hyperthermal (HHT) oxygen atom emission from nanostructured CaO excited by 6.4 eV nanosecond laser pulses. The kinetic energy distribution of emitted O-atoms peaks at 0.7 eV, which is over 4 times greater than previously observed. Excitation of MgO and CaO nanostructures with UV laser pulses is known to result in thermal and hyperthermal emission of oxygen atoms when photons with energies above and below the band gap, respectively, are used. The highly energetic atomic desorption we observe, following bulk excitation, challenges the conventional view that bulk excitation can only induce thermal desorption. Using density functional theory and an embedded cluster method, we propose a mechanism for this HHT feature based on the interaction of surface holes with bulk excitons. These experimental and theoretical results suggest that specific atomic desorption mechanisms in wide-bandgap materials can be controlled by selective electronic excitation of not only the surface but also the bulk of these materials.
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