Jump to contact, neck formation, and surface melting in the scanning tunneling microscope

Abstract

With a scanning tunneling microscope the Pb (110) surface was studied from room temperature to temperatures where surface melting occurs. At room temperature scanning tunneling microscopy images of Pb(110) can be recorded with atomic resolution. At higher temperatures we observe a jump to contact by the surface, resulting in the formation of a connecting neck of Pb between the surface and the tip. As the tip is retracted, the neck elongates and finally breaks. The dependence of the average neck height just before rupture on temperature and retraction speed suggests that mobile adatoms are responsible for the growth of the neck.