In situ and real time X-ray diffraction study of interdiffusion at the Ag/Au(111) interface after electrolytic deposition

Abstract

We have previously used laboratory based X-ray diffraction to observe that underpotentially deposited Ag on Au(111) formed a structure with a spacing (normal to the surface plane at the interface) that was out of phase with the Au(111) atomic planes. We have also recently used the same technique to observe the expected diffusion controlled epitaxial growth of Ag on Au(111) during electrolytic bulk deposition. Both measurements were made at the electrode/electrolyte interface in situ and in real time. However, in the work reported here, we have observed the existence of a structure at the Ag/Au(111) interface that diffracted X-rays out-of-phase with the Au(111) planes after bulk electrolytic deposition of Ag. We attribute this phenomenon to interdiffusion between the Ag and the Au(111) lattice at the interface. Furthermore, we have observed that the structure diffracting X-rays out-of-phase switched to one diffracting in-phase after a period of time. This implies that we were able to monitor the process of interdiffusion between Ag and Au both in situ and in real time.