The Study of Alloy Surfaces by Plasmon Excitation.
Final rept. 1 Oct 75-31 Aug 78,
YALE UNIV NEW HAVEN CONN DEPT OF ENGINEERING AND APPLIED SCIENCE
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The surface plasmon dispersion relation for the 100 surface plane of aluminum has been measured by electron energy loss spectroscopy at glancing incidence, which completely suppresses the volume plasmon and minimizes multiple scattering. The dispersion relationship, compares favorably with the only other measurement made by a different technique, ILEED on a well characterized single crystal surface. The results of the two independent measurements disagree substantially with all of the numerous dispersion relationships which are computed for different models of the surface charge density profile and which employ different computational approximations. However, the negative sign of the linear coefficient-1.9, which is related to the density fluctuation of surface plasmons, is established and it may be interpreted to mean that the maximum in the surface charge fluctuation occurs inside the metal, rather than symmetrically about the surface plane. An appendix describes the effect of adsorbed oxygen on the energy loss spectra obtained from a clean surface. The surface plasmon peak at 10.3 eV is displaced by a new peak at 7.5 eV as oxygen exposure torr-seconds is increased. At large exposure of oxygen a broad peak appears at 20.6 eV. Plasmon dispersion was measured during oxygen exposure and it was found to be constant until the 10.3 eV plasmon peak disappears from the spectrum.
- Metallurgy and Metallography
- Electricity and Magnetism
- Plasma Physics and Magnetohydrodynamics
- Solid State Physics