SURFACE-STRUCTURE OF ALPHA-GA(010)

We have determined the surface structure of alpha-Ga(010) near its mel ting point using x-ray diffraction. Of the two possible ideal ways to form the (010) surface, we find that the true surface is formed by cut ting through dimer bonds (i.e., between metallic bilayers). The contra ction of the metallic bonds and the expansion of the covalent bonds at the surface imply that the surface is more metallic than the bulk. Ou r results suggest that a-Ga is fundamentally composed not of Ga-2 dime rs, but of corrugated metallic bilayers which can be modeled as deltah edral clusters.