Surface phonons of TiC(310)

We have observed the vibrational spectrum of a stepped surface, the TiC(310) surface by means of electron energy loss spectroscopy (EELS). Apart from two losses at 61 and 80 meV, which are similar to those observed for the flat TiC(100) surface in specular direction, three new loss features appear at the G{cyrillic}-point at 18, 28 and 49 meV respectively. These loss peaks are due to a "backfolding" of surface phonons. Small frequency shifts are caused by a "mixing" of these modes. All frequencies can be reproduced by our lattice dynamical calculations if we assume that the force constants for the terrace atoms are very similar to the force constants at the flat TiC(100) surface. Only the force constants in the vicinity of the steps have to be changed.