Localized and Delocalized Features of Microscopic Work Functions

Abstract

Highly localized and widely delocalized features of the microscopic work function have been observed on the basis of the local tunneling barrier height by means of scanning tunneling microscopy. The eŠect of work function reduction by Cs adsorption on Pt(111) extends over an area wider than tens of nanometers. On the other hand, the individual atoms on NiAl (110) show element-speciˆc local work functions. These results indicate that the work function distribution can not be explained within the framework of electric dipoles induced by surface atoms, and that detailed features of wave functions should be taken into account.