The first experimental measurement of the Rayleigh mode dispersion curve for the Al(100) surface is reported. Excellent agreement is found between the experimental results and the theoretical first-principles calculation performed by Bohnen and Ho [J. Vac. Sci. Technol. A5, 462 (1987)] for the phonon energy at X¯. This is to be contrasted with the large discrepancy reported by Toennies and Wöll [Phys. Rev. B 36, 4475 (1987)] between the experimental and theoretical values at X¯ for the Al(110) surface.

• Received 4 November 1987

DOI:https://doi.org/10.1103/PhysRevB.37.6519