Scanning tunneling microscope study of bromine adsorbed on the Ag(111)surface

Bromine adsorbed silver (111) surfaces with (root 3 x root 3)R30 degrees and (3 x 3) phases were studied by scanning tunneling microscopy at room temperature. For the (root 3 x root 3)R30 degrees surface, no feature associated with the Br overlayer could be obtained: only the substrate (1 x 1) structure was observed. On the other hand, for the (3 x 3) phase, it was revealed that a bromine overlayer is formed with hexagonal arrangement, of which the lattice constant is 3/2 that of the substrate. It was also found that the coadsorbed cadmium atoms change the Br overlayer structure. (C) 1999 Elsevier Science B.V. All rights reserved.