Sapphire (11 2 0) surface: Structure and laser-induced desorption of aluminum

Journal Article · Sat Mar 14 23:00:00 EST 1992 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.45.6197· OSTI ID:7272217

Schildbach, M A ^[1]; Hamza, A V ^[2]

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1. Department of Applied Science, University of California at Davis/Livermore, Livermore, California 94550 (United States)
2. Department of Chemistry and Material Science, University of California, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

The laser-induced desorption of particles from a well-characterized sapphire (11{bar 2}0) surface at laser wavelengths of 1064 nm (1.17 eV) and 355 nm (3.51 eV) was investigated by time-of-flight mass spectrometry. Below the laser ablation threshold, only aluminum ions were observed to desorb with average kinetic energies of 7.0{plus minus}0.7 eV at both photon energies. The high kinetic energies of the desorbing aluminum ions indicate that the desorption mechanism is electronic. The surface atomic and electronic structure was studied with low-energy electron diffraction (LEED), reflection electron-energy-loss spectroscopy, and Auger electron spectroscopy. After heating the surface to over 1500 K, a reconstructed surface exhbiting a (12{times}4) LEED pattern was established. The electron-energy-loss spectrum from the (12{times}4) surface revealed the presence of surface electronic states in the bulk band gap of sapphire as evidenced by a broad ({similar to}2 eV full width at half maximum) energy-loss feature centered at 3.6 eV. The surface electronic states are believed to participate in the photon-absorption process.

• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 7272217
• Journal Information: Physical Review, B: Condensed Matter; (United States), Journal Name: Physical Review, B: Condensed Matter; (United States) Vol. 45:11; ISSN 0163-1829; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360606* -- Other Materials-- Physical Properties-- (1992-)
ALUMINIUM
AUGER ELECTRON SPECTROSCOPY
CHEMICAL REACTIONS
CHEMISORPTION
COHERENT SCATTERING
CORUNDUM
DIFFRACTION
ELECTROMAGNETIC RADIATION
ELECTRON DIFFRACTION
ELECTRON SPECTROSCOPY
ELEMENTS
ENERGY LOSSES
ENERGY RANGE
EV RANGE
EV RANGE 01-10
LASER RADIATION
LOSSES
METALS
MINERALS
OXIDE MINERALS
RADIATIONS
SAPPHIRE
SCATTERING
SEPARATION PROCESSES
SORPTION
SPECTROSCOPY
SURFACE PROPERTIES