DEFORMATION OF OCTAHEDRA AT LAB6(100) SURFACE STUDIED BY HREELS

The surface phonons of LaB6(100) surface have been investigated by mea ns of high resolution electron energy spectroscopy. On the clean surfa ce we have observed 8 loss peaks in the off-specular spectra, of which the higher energy losses are related to the vibrations of the three-d imensional network of boron. Theoretical analysis based on a force con stant model strongly suggests the deformation of the three-dimensional network of boron; the topmost octahedra are expanded by approximately 0.004 nm parallel to the surface.