In situ STM studies of sulfur and thiocyanate adlayers on Cu(1 1 1) in alkaline solution

Adlayers of sulfur (S) and thiocyanate (SCN−) on Cu(1 1 1) were investigated by using in situ scanning tunneling microscopy in alkaline solution. Two different structures of S adlayers, (√3×√3)R30° and (19×19), were revealed in the double-layer potential region. The (√3×√3)R30° structure observed at negative potentials was transformed into (19×19) on sweeping the potential in the positive direction. For SCN− on Cu(1 1 1), the (√3×√3)R30° structure was also observed at negative potentials. At positive potentials, a structural change was observed also for the SCN adlayer; however, the adlayer structure was much distorted compared with the (19×19) structure of the S adlayer.