C-60 thin films on Ag(001): an STM study

The structure of submonolayer C-60 films deposited on Ag(001) is studied as a function of the substrate temperature in the range 100-700 K. Morphologi cal aspects such as island shape and preferential nucleation sites are in a greement with the theory of submonolayer deposition. A peculiar irreversibl e transition which leads to the onset of brightness differences between mol ecules of the same film is observed at around 300 K. This effect is ascribe d to electronic differences due to non-equivalent orientation of the C-60 m olecules on the surface rather than to murphological differences induced by a surface reconstruction. (C) 1999 Elsevier Science Ltd. All rights reserv ed.