STM IMAGING OF THE SURFACE OF SMALL METAL PARTICLES FORMED IN ANODIC OXIDE PORES

The surfaces of Fe, Ni, and Au particles formed by ac electrolysis in the uniform pores of anodic aluminum oxide have been imaged at varying magnifications using SEM, TEM, and STM. Particles of Fe and Ni are found to be rod shaped while those of Au are ellipsoidal or spherical. Parallel ridges along the length of the Fe and Ni particles with a mean separation of approximately 80 angstrom indicate that pore formation rate is not angularly uniform about the central axis of the pore. Atomically resolved images of the Au particles reveal an unreconstructed (110) surface as well as twinned (111) surfaces. The observation of twinned microcrystallites is speculated to indicate that a transition had occurred from an icosahedral structure to a cubic form as the particle grew in size.