High‐Purity Er$_{3}$N@C$_{80}$ Films: Morphology, Spectroscopic Characterization, and Thermal Stability

Films comprising the endohedral fullerene Er3N@C80 are deposited onto highly
oriented pyrolytic graphite (HOPG) substrates in high purity enabled by performing
mass-selected low-energy deposition from a cation beam. In the initial
stage, the growth on HOPG is dominated by spontaneous nucleation of small 2D
islands both on intact terraces as well as the step edges. The island growth
exhibits strong differences from lms comprising other fullerenes grown by the
same method. This behavior can be explained by the surface-diffusion-mediated
nucleation model presented in previous work: Dominant components in the
behavioural differences are a high intercage dispersion interaction and a lower
kinetic energy of cages migrating on the surface in comparison with previously
deposited materials. When annealed, the lms undergo several competing
processes: A small fraction desorbs in the temperature range 700–800 K, another
fraction forms covalent intercage bonds instead of the previous purely dispersive
bonding mode, and a third fraction probably decomposes to small fragments.