Surface-Plasmon Dispersion in A1(111) Films

Abstract

The extraction of the surface-plasmon dispersion relation from experimentally measured inelastic low-energy- ($20\lesssim E\lesssim 200$ eV) electron diffraction intensties on A1(111) films is described. Our analysis is based on the two-step model of inelastic diffraction. Attention is focused on the methodology of determining the model parameters from the data analyses, the internal consistency of parameters obtained from the consideration of independent data, and the accuracy of the values of the parameters as determined using our procedure. Examination of eight independent sets of experimental intensities leads to the dispersion relation $\hslash {\omega }_s\left(p_{\parallel }\right)=10.5(\pm 0.1)+2(\pm 1)p_{\parallel }+0\mathrm{}(+2\mathrm{})\mathrm{}{p}_{\parallel }^2$; ${\Gamma }_s\left(p_{\parallel }\right)=1.85(\pm 0.5)+3(\pm 2)p_{\parallel }$, for energies measured in eV and momenta in ${\mathrm{\AA }}^{-1\mathrm{}}$.