Adsorption and decomposition of C60 on Ni(1 1 0) surfaces

In the present paper we study the adsorption of C60 on Ni(1 1 0) surfaces at RT and 650 K, as well as the desorption/decomposition process. The investigation took place in UHV by means of Auger electron spectroscopy, low energy electron diffraction, thermal desorption spectroscopy and work function (WF) measurements. The observed overlayer structures during C60 deposition at 650 K are in complete agreement with reported results. The sticking coefficient is nearly the same for both RT and 650 K. Heating of the 1 ML C60-covered Ni(1 1 0) surface, however, at 750 K, causes a partial fragmentation of C60 to a 2D graphite-like layer, while the remaining C60 molecules are rearranged in the (5×3) structure, in contrast to reported results. Further heating to 800 K results in the complete fragmentation of C60 accompanied by carbon desorption, possibly in molecular Cn (n>10) form. Above 800 K, the C of the graphite-like layer is desorbed in both atomic and molecular form. The WF at saturation coverage was found to be 5.61 eV for both deposition at RT and 650 K. This value is substantially greater than the average value of 5 eV, which has been suggested to hold for C60 overlayer systems, regardless of the metal substrate.