Motion of Surface Atoms on Small Gold Particles Revealed by HREM with Real-Time VTR System

A new method of high resolution electron microscopy utilizing a real time VTR-TV monitor system has been developed for the study of small metal particles less than 100 Å in size. The study for the first time revealed the real time motion of the surface atoms on a 100 Å gold cluster. The particle is a cuboctahedron and its {111} and {100} type surface are viewed as their edge-on projections along the <110 > direction. The surface atomic steps are formed on the {100} type surfaces but not on the {111} surfaces. The steps frequently change their positions within less than one tenth of a second. This motion is direct evidence of the random walk of the surface atoms on metal surfaces.