AU(111) 23X-ROOT-3 SURFACE AS A TEST SURFACE FOR COMPARING THE ATOMICFORCE AND SCANNING TUNNELING MICROSCOPES

The first observation of a surface reconstruction with an atomic force microscope (AFM) is reported. The Au (111) p x square-root 3 (p appro ximately 22-30) surface under electrochemical potential control has be en studied. Values for the periodicities and corrugation of the recons truction that are similar to those found with a scanning tunneling mic roscope (STM) are obtained. This is an important test of instrumental artifacts owing to the high electric field and uncontrolled contact fo rce in the STM. The STM consistantly yields higher resolution of the r econstruction, although both techniques also consistantly show an ''at omic'' lattice at high magnification. This apparent contradiction sugg ests that the atomic resolution in the AFM may be caused by atomic-sca le periodicity in the tip-substrate interaction rather than by true si ngle atom contact. This cannot be explained by tip geometry because th e corrugation of the p X square-root 3 reconstruction is much less (ap proximately 0.15 angstrom) than the height of a single atomic step on the Au (111) surface.