The potential (E)-dependent transformations of adsorbed sulfur on Au(111) i
n 0.1 M NaOH + 3 x 10(-3) M Na2S have been followed by in situ STM imaging.
When E is changed from -0.6 to -0.8 V, the transformation from rectangular
S-8 surface structures to a root 3 x root 3 R30 degrees S lattice takes pl
ace. This process involves sulfur atom desorption, the formation of rectang
ular tetramerical surface structures, and the displacement of sulfur atoms
to nearest hollow sites, When E moves from -0.8 to -1.0 V fast desorption o
f the root 3 x root 3 R 30 degrees lattice from Au (111)terraces is observe
d while sulfur atoms become progressively bonded to step edges. Sulfur atom
readsorption to form the root 3 x root 3 R 30 degrees lattice takes place
by returning to E = -0.8 V. Experimental data provide an estimation of the
excess of binding energy close to step edges.