TAC(110) - A PERIODIC FACET RECONSTRUCTION STUDIED BY LEED AND STM

A simple model is established to describe diffraction phenomena (LEED) from a unidirectionally reconstructed TaC(110) surface. By comparing diffraction data with results of detailed simulations, the reconstruct ion is found to consist of alternate (100) and (010) facets propagatin g periodically along the [11(0) over bar] direction like an irregular ridge-and-valley grating, with (110) terraces completely absent. The i rregularity is due to variation in facet sizes, and the mean separatio n is determined to be L = 6 lattice spacings. The validity of this mod el is supported by STM imaging results which confirm the structure obt ained from the LEED-data analysis.