Direct determination of the reaction path of Sb4 on Si(001) with scanning tunneling microscopy

The complex reaction path of the dissociative chemisorption of Sb4 on Si(001) involving four distinct types of precursor states is determined using a direct tracking method with scanning tunneling microscopy. The energy barriers and the prefactors for the transitions between different states are measured by analyzing the population distribution of Sb clusters as a function of thermal treatment. These precursors are found not to have thermal mobility before dissociation, contrary to the widely held notion about precursor states. © 1993 The American Physical Society.