Scanning tunneling microscopy and x-ray photoelectron diffraction investigation ofC60films on Cu(100)

Abstract

Ultrathin ${\mathrm{C}}_{60}$ films grown on a Cu(100) surface in ultrahigh vacuum have been investigated by scanning tunneling microscopy (STM) and x-ray photoelectron diffraction (XPD). STM observations show that following deposition at room temperature ${\mathrm{C}}_{60}$ molecules decorate substrate steps and order in densely packed extended islands and layers. Two kinds of contrast, i.e., different apparent heights, are encountered in the film evolution, which are associated with substrate reconstruction and inequivalent ${\mathrm{C}}_{60}$ bonding. At elevated temperatures (500–600 K) a striped regular ${(}_{04}^{106})$ superstructure is obtained comprising two distinct ${\mathrm{C}}_{60}$ species. From an XPD analysis of this phase the corresponding possible ${\mathrm{C}}_{60}$ bonding configurations could be determined.