The influence of the surface nature on scattering, fragmentation and deposition processes in C60+ collisions with solid surfaces Original Research Article

Surface collision experiments with C60+ ions under UHV conditions were carried out to study the influence of the surface atomic mass, structure, and chemical reactivity of a variety of crystalline surfaces on different collision processes. The impact energy was varied from about 100 to 700 eV. Collisions with graphite (0001), diamond (111), and tungsten diselenide (0001) yield scattered C60+ ions which were analyzed with respect to their final kinetic energy and rate of metastable fragmentation by means of velocity selective time-of-flight mass spectroscopy. With increasing mass of the surface atoms, the final kinetic energy decreases along with a rise of the final internal energy as deduced from the rate of metastable fragmentation. In strong contrast, C60+ collisions with Ni(100) and Cu(100) did not result in a detectable yield of scattered ions. Auger electron spectroscopy (AES) showed carbon deposition on these two surfaces. However, the surface carbon concentration as a function of the C60+ exposure dose depicts remarkable differences. On Ni(100), the carbon concentration rapidly rises at low exposure doses until saturation is reached. By means of low energy electron diffraction (LEED), a c(2×2) carbon superstructure was found. On Cu(100), the carbon concentration steadily rises with increasing slope. The blurring of the Cu(100) electron diffraction spots gives evidence that the surface becomes damaged under C60+ bombardment resulting in carbon-binding defects. Finally we show that C60+ collisions with fullerite surfaces are nearly elastic for impact energies up to 250 eV. Rainbow scattering was observed for this surface. For higher impact energier sputtering becomes dominant.