Dynamics of Pb deposits on the Si(100)2X1 surface at room temperature

We have studied by scanning tunneling microscopy at room temperature the dy namics of Pb deposits on the Si(100)2 x 1 surface. The deposit consists of long one-dimensional rows of dimers (chains), where two kinds of terminatio ns are observed. The long chains coexist with short ones, that consist of o ne or two protrusions. We have observed gains and losses of atoms at the en d of these structures. From the analysis of these events, we have obtained information on the nature and the stability of the terminations, and on the nucleation process of the chains on the terraces.