The surface-phonon dispersion curves of the TiC(100) surface along both the M and X azimuths of the two-dimensional Brillouin zone have been measured by electron-energy-loss spectroscopy (EELS). We have observed two acoustical-phonon branches (Rayleigh and resonance modes) and three optical-phonon branches (Wallis, Lucas, and new modes). Those experimental curves are in good agreement with the theoretical ones calculated on the basis of a screened-shell model. In this calculation, the 20% stiffening of the stretching force constant between the first-layer Ti atom and the second-layer carbon produces a quasitransverse mode localized strongly at the second-layer carbon, which corresponds to the new observed surface mode. The local spectral densities calculated with use of these parameters have been compared with the experimental EELS spectra.
ASJC Scopus subject areas
- Condensed Matter Physics