Metal-overlayer formation onC60for Ti, Cr, Au, La, and In: Dependence on metal-C60bonding

Photoelectron spectroscopy using x rays and synchrotron radiation was used to examine surface bonding and overlayer growth modes when the representative metals Ti, Cr, Au, La, and In were deposited onto thin films of pure ${\mathrm{C}}_{60}$. None of these metals intermixed with ${\mathrm{C}}_{60}$ or formed bulk metal-fulleride compounds. Instead, metallic clusters were produced when Au, Cr, and In atoms were condensed on ${\mathrm{C}}_{60}$. For Ti and La, the first layer formed as a monolayer but subsequent depositions produced clusters. The tendency to form a single layer for Ti and La reflects the hybridization of metal d and fullerene p orbitals, as with bulk carbides. In addition, limited amounts of metal carbide formation was evident for overlayers of Ti, La, and Cr due to some disruption of ${\mathrm{C}}_{60}$.