Atomic observation of the sublimation process of the Pb (111) surface

The dynamic behavior of the sublimation process using ultrafine Pb particles produced by the gas evaporation technique was examined at the level of atomic resolution using a transmission electron microscope equipped with a real-time video-recording system. The ultrafine Pb particles coated with a carbon layer with a thickness of the order of 5 nm were prepared in the electron microscope by heating particles on carbon film at 300°C. Sublimation of the Pb particle covered with the carbon layer took place above 470°C, which is slightly higher than the melting point of Pb. Sublimation occurred at the surface with a higher surface energy. The sublimation process of the (111) surface was clearly observed at an atomic level. It was found that two- or four-atomic-layer step flow was observed at the (111) surface. At the (111) surface between the stacking faults, two-layer and successive one-layer sublimation occurred.