AVS 47th International Symposium
    Surface Science Wednesday Sessions
       Session SS-WeP

Paper SS-WeP23
Electron-Stimulated Desorption of Europium Atoms from Oxidized Tungsten Surfaces

Wednesday, October 4, 2000, 11:00 am, Room Exhibit Hall C & D

Session: Poster Session
Presenter: V.N. Ageev, A. F. Ioffe Physico-Technical Institute, Russia
Authors: V.N. Ageev, A. F. Ioffe Physico-Technical Institute, Russia
Yu.A. Kuznetsov, A. F. Ioffe Physico-Technical Institute, Russia
T.E. Madey, Rutgers, The State University of New Jersey
Correspondent: Click to Email
We have measured the electron-stimulated desorption (ESD) yield for neutral europium (Eu) atoms from Eu layers adsorbed on oxidized tungsten surfaces, as a function of electron energy, europium coverage, degree of oxidation of tungsten and surface temperature. The objective is to compare ESD of multivalent Eu with ESD of monovalent alkali atoms, studied previously. The measurements have been carried out using a time-of-flight method and surface ionization detector. The Eu ESD desorption yield is a complicated function of Eu coverage, electron energy E@sub e@ and substrate temperature. In the coverage range 0.05 to 0.35 monolayers (ML), thresholds for Eu desorption are observed at electron energies E@sub e@ of 25 and 37 eV, and are associated with Eu 5p and 5s excitations. Additional features (resonant-like peaks) are seen at E@sub e@ = 50 eV and 80 eV; these are associated with W 5p and 5s, respectively, and are observed even for Eu coverages > 1 ML. The Eu yields at 25 and 37 eV vanish above 330K, whereas the yields at 50 and 80 eV persist above 500K. This is the first report of ESD of metal atoms in which threshold features correlate both with adsorbate excitation energies and substrate excitation energies.