IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Surface Science Tuesday Sessions
       Session SS3-TuP

Paper SS3-TuP8
Resonances in Electron-Stimulated Desorption of Europium Atoms from Oxidized Tungsten: Effects of Temperature

Tuesday, October 30, 2001, 5:30 pm, Room 134/135

Session: Adsorption/Desorption Poster Session
Presenter: V.N. Ageev, Academy of Sciences of Russia
Authors: V.N. Ageev, Academy of Sciences of Russia
Yu.A. Kuznetsov, Academy of Sciences of Russia
N.D. Potekhina, Academy of Sciences of Russia
T.E. Madey, Rutgers, The State University of New Jersey
Correspondent: Click to Email
The electron-stimulated desorption (ESD) yield for neutral europium (Eu) atoms from Eu layers adsorbed on oxidized tungsten surfaces has been measured as a function of electron energy, europium coverage and degree of oxidation of tungsten, with an emphasis on effects of substrate temperature. The measurements have been carried out using a time-of-flight method and surface ionization detector. We expand on an earlier report, and compare ESD of multivalent Eu with ESD of monovalent alkali atoms, studied previously. The Eu atom ESD is a complicated function of Eu coverage, electron energy and substrate temperature. In the coverage range 0.05 to 0.35 monolayer (ML), overlapping resonant-like Eu atom yield peaks are observed at electron energies of 36 and 41 eV that might be associated with Eu 5p and 5s level excitations. Additional resonant - like peaks are seen at electron energies of 54 and 84 eV that are associated with W 5p and 5s level excitations. The Eu atom yield peaks at 36 and 41 eV are seen only in the temperature range 220 to 300 K at an europium coverage of 0.07 ML, and the temperature range becomes narrower with increasing europium coverage. In contrast, the peaks at 54 and 84 eV persist above 500 K. The surface ionization current calculations show that the yield associated with the tungsten core level excitations may arise from the ESD of EuO molecules rather than Eu atoms. This is the only reported system for which the electron energy dependence of neutral ESD yield has a resonant character, in the absence of a non-resonant background.