Münster 1997 – wissenschaftliches Programm

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O: Oberflächenphysik

O 6: POSTER I

O 6.27: Poster

Montag, 17. März 1997, 14:15–15:45, AULA

The Effect of Oxygen Adsorption on (e,2e) Spectra of W(001) — •S. Samarin, O. Artamonov, H. Schwabe, and J. Kirschner — Max-Planck-Institut für Mikrostrukturphysik, Halle

Two-dimensional energy distributions of correlated electron pairs
((e,2e) spectra) excited by electrons with energies between 18 eV and 34 eV at grazing incidence were measured from clean and oxygen covered W(001) surface by a time-of-flight (e,2e) spectrometer. Adsorption of 0.13 ML of oxygen suppresses the excitation of correlated electrons from the energy levels (0.1 - 0.5) eV and (3.5 ±0.5) eV below Fermi level. These energies correspond rather well to the energy positions of the surface resonances found on the W(001) surface in photoemission and field emission experiments [1]. At higher oxygen coverage (0.5 ML) and higher incident electron energy (33.6 eV) a new maximum corresponding to the excitation of correlated pairs from the energy level 6 eV below Fermi level was found in (e,2e) spectrum. This result is consistent with the UPS study of oxygen adsorption on W(001) [2] where the adsorbate photoemission peak was observed at 6 eV below Fermi level.

[1] Shang-Lin Weng, E.W. Plummer, and T. Gustafsson, Phys. Rev. B 18 4, 1718 (1978).

[2] A.M. Bradshaw, D. Menzel, and M. Steinkilberg, Japan. J. Appl. Phys. Suppl. 2 Pt. 2, 841 (1974).