HIGH FLUENCE ION IRRADIATION OF THIN FULLERITE FILMS

Thin fullerite films - partly covered with a thin Au - layer have been irradiated with 100 keV Arn+ (n = 1, 6, and 12), 250 keV N+, and 30 k eV Au+ ions up to high fluences, and subsequently analyzed by profilom etry, Rutherford Backscattering Spectrometry (RBS), and Atomic Force M icroscopy (AFM). Depending on the system, either an increase or a decr ease of the film thickness after the irradiations was found, and the p robing RES alpha particles suffered sometimes an enhanced, and sometim es a reduced energy loss upon passage through the films. The compariso n of profilometry and RES results on uncovered and covered samples all ows us to separate the different effects which influence the behavior of high-fluence irradiated fullerite samples clearly from each other. Such effects might be the incorporation of the projectile ions, densit y changes, phase changes, sputtering, and transport of neighbored unir radiated matter into the irradiated zone. It is remarkable that ion ir radiation of fullerite can lead as well to a densified material, with densities of about 2.1 g.cm(-3), as to a foam-like carbonaceous materi al with a density around 0.35 g.cm(-3) - depending on the type of proj ectile and its range. The latter case appears to be characteristic for high-fluence heavy noble gas implantation into fullerite. Fullerite s puttering was reconfirmed to decrease inversely with the fluence.