AVS 45th International Symposium
    Surface Science Division Wednesday Sessions
       Session SS2-WeA

Paper SS2-WeA4
Photodesorption of Positive Ions from Oxyanion-Containing Inorganic Crystals

Wednesday, November 4, 1998, 3:00 pm, Room 309

Session: Photochemistry and Deposition
Presenter: C. Bandis, Washington State University
Authors: C. Bandis, Washington State University
M.L. Dawes, Washington State University
S.C. Langford, Washington State University
J.T. Dickinson, Washington State University
Correspondent: Click to Email
Surfaces of inorganic, ionic crystals with complex oxyanions can be dramatically altered by UV and electron irradiation. Previous work has shown that such irradiation desorbs XO@sub n@ and O@sub 2@, where X = N, P, C, and possibly S. This electronic decomposition produces cation defect complexes from which intense positive ion emission can be photo-induced. We describe two-beam experiments where either two laser beams or a laser and an electron beam are cofocused. One beam (UV laser or electron) is used to generate defects, and the second beam (laser) is used to photodesorb ions. We report metal and metal-containing ion emission accompanying nanosecond laser pulses at 248 and 1064 nm from alkali nitrates and calcium phosphates. The resulting ion kinetic energies can exceed the photon energy by factors of ten. The effect of time delay between two pulsed beams will also be presented. The critical role of radiation induced chemistry and the ion emission mechanism will be discussed. This work is supported by the Department of Energy under Contract DE-FG06-92ER14252.