INSITU ELECTROCHEMICAL SCANNING TUNNELING MICROSCOPY STUDY OF THE STRUCTURAL-CHANGES OF SILVER SURFACES FOLLOWING AN OXIDATION REDUCTION CYCLE IN 1M-KCL

In situ electrochemical scanning tunneling microscopy (ESTM) was employed to observe the surface of silver immersed in 1M KCl before and after an oxidation-reduction cycle (ORC). The roughness created by ORC was found to relax quickly. During the first 2 min marked decreases in surface area occur that are accompanied by the disappearance of nanometer size features. The rate of change in surface area decreases significantly after this time. Further decreases in surface energy are brought about by the growth of crystal planes which become apparent during the first 3-5 min. Some of these planes appear to be low index planes {111}; these have the lowest surface energy. The results of the present study suggest that the time evolution of surface enhanced Raman scattering (SERS) following an ORC of silver can be contributed to by changes in atomic scale roughness (less-than-or-equal-to 30 angstrom) as well as submicroscopic roughness (approximately 500 angstrom).