STEP DYNAMICS AT THE AG(111)-ELECTROLYTE INTERFACE

Monoatomic high steps on Ag(111), which look frazzled in STM images due to the movement of kink sites have been studied in sulfuric acid electrolytes by in situ scanning tunneling microscopy with atomic-scale resolution. The width of the frizzy region was found to depend on the electrode potential. While at around -120 mV versus SCE the width is about the same as in air, it increases with potential until at very positive values, i.e., close to the Ag dissolution potential, the frizzy region extends over two and more atomic diameters for normal scan rates. At +80 mV versus SCE the average width is about four times larger than for silver in air suggesting a very high mobility of kinks at the Ag-solution interface under such conditions. Steps emerging at a screw dislocation were found to be non-frizzy as long as they have not yet reached monoatomic height. From an analysis of STM images and x-t scans the velocity of kink sites moving along steps has been estimated.