Accession Number : ADP007917

Title :   The Adsorption of 1.17 eV Photons by A1 sub 2 O sub 3 (1120),

Corporate Author : LAWRENCE LIVERMORE NATIONAL LAB CA

Personal Author(s) : Schildbach, M. A. ; Hamza, A. V.

Report Date : 22 MAY 1992

Pagination or Media Count : 4

Abstract : Recently, it has been proposed that multiphoton absorption by wide band gap materials is an important mechanism for energy absorption on surfaces ultimately leading to laser-induced surface damage. Many authors have observed non-thermal, photon-stimulated desorption of particles with radiation at energies less than the band gap of the solid material sample. The multiphoton nature of the process was gleaned either from the dependence of the particle yield on photon fluence or by the fact that the single photon energy was insufficient to excite electrons across the band gap. In cases where the number of photons required in the process is large (>3), the assistance of surface or defect states in the band gap has been proposed as the origin of photon absorption or as states that resonantly enhance the multiphoton absorption. However, the surfaces studied have not been sufficiently well-characterized to confirm the proposed mechanism.

Descriptors :   *ABSORPTION, *LASER PUMPING, DAMAGE, DESORPTION, ELECTRONS, ENERGY, MATERIALS, PARTICLES, PHOTONS, RADIATION, SOLIDS, ALUMINUM OXIDES, SURFACE CHEMISTRY, PHOTOCHEMICAL REACTIONS.

Subject Categories : Physical Chemistry
      Radiation and Nuclear Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE