Scanning tunneling microscopy of Dy@C82 and Dy@C60 adsorbed on Si(111)-(7x7) surfaces

Dy@C-82 and Dy@C-60 adsorbed on Si(111)-(7x7) surface are investigated by scanning tunneling microscopy (STM) at 295 K. The Dy@C-82 molecules in the first layer are adsorbed on the Si(111)-(7x7) surface without formation of islands and nucleation, and the internal structure of the Dy@C-82 molecule is first observed on the surface at 295 K. The average heights of the Dy@C-82 molecules in the first and second layers are estimated to be 7.2 and 10.8 A, respectively, by STM. These results suggest strong interactions between the Si atoms and the Dy@C-82 molecules in the first layer. The STM image reveals that the Dy@C-60 molecule is nearly spherical, showing that the metal endohedral C-60 possesses a cage-form structure.