Surface lattice dynamics of Cu(111)
We present and analyze off-specular electron-energy-loss data which explore surface vibrations of Cu(111), along the line from Gamma-bar to M-bar in the two-dimensional surface Brillouin zone. The dispersion relation of the Rayleigh surface phonon and the longitudinal resonance found in inelastic-He-scattering studies have been measured out to M-bar, thus extending the earlier He work. In addition, we obtain the frequency of a (high-frequency) surface phonon which exists at and near M-bar, in a gap in the projected bulk-phonon density of states. The data are analyzed within a simple model of surface lattice dynamics. We have also carried out extensive calculations of the energy variation of the various features observed in the electron-loss spectrum, using multiple-scattering theory. Very good agreement between theory and experiment is obtained within a model where the intraplanar force constant between surface atoms is softened by a modest amount, 15%. In our view, the results presented here raise questions about recent suggestions that a very large (70%) softening of the intraplanar surface force constant is present in the Cu(111) surface.
- Research Organization:
- The Institute for Surface and Interface Science and Department of Physics, University of California, Irvine, California 92717
- OSTI ID:
- 7092004
- Journal Information:
- Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 38:9; ISSN PRBMD
- Country of Publication:
- United States
- Language:
- English
Similar Records
Phonon dynamics and structure of the deuterated diamond(111)-(1{times}1) surface: Experiment and theory
Cu(111) and Ag(111) surface-phonon spectrum: The importance of avoided crossings