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    The Interaction of 1064 nm Photons with the Al2O3(110) Surface

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    Low energy electron diffraction (LEED), Auger electron spectroscopy (AES), and electron energy loss spectroscopy (ELS) were used to characterize Al2O3(110) surfaces before and after exposure to Nd:YAG 1064 nm, 1.17 eV photons. The clean and well-annealed (Ts>1500K) surface exhibited a (12×4) LEED pattern. Irradiation of the surface with laser fluences of approximately 3.5 J/cm2,30% of the visible damage threshold, degraded the surface to the point that the (12×4) diffraction beams were no longer detectable. Characterization of the laser-irradiated surface by AES failed to show any departure from the (12×4) surface, unlike electron beam damage of alumina where the desorption of oxygen leaves metallic aluminum. However, subsequent annealing to 1700 K was sufficient to restore the original pattern. ELS of the (12×4) surface showed the presence of surface electronic states in the bulk band gap with energy losses between 3 and 5 eV.

    Time-of-flight (TOF) spectra of laser-desorbed species obtained with a quadrupole mass spectrometer revealed that at fluences less than those leading to catastrophic surface damage, the desorbing flux was predominantly aluminum (atoms and ions). The energy of the desorbing aluminum was approximately 8 eV, the energy required to promote an electron from the valence band maximum to an exciton localized on the aluminum atom. At fluences which produce visible surface damage, oxygen molecules are observed in addition to aluminum in the desorbing flux.

    Author Information:

    Schildbach, MA
    Lawrence Livermore National Laboratory, Livermore, California

    Hamza, AV
    Lawrence Livermore National Laboratory, Livermore, California

    Committee/Subcommittee: F01.19

    DOI: 10.1520/STP23621S