Quantitative analysis of EELS spectra on the growth of C₆₀ thin film on graphite

We present a quantitative analysis of electron energy loss (EEL) spectra to investigate the initial growth of C₆₀ thin films on a graphite substrate at room temperature. The approach is to fit the experimental data to a parameterized simulation, which includes both a growth model and the treatment of electron scattering. A rate equation approach is used to characterize the growth by a single parameter, the probability of a molecule descending to the preceding layer when approaching an island edge. The scattering dynamics is described by a layer-dependent cross section and a constant mean free path. The results indicate that the initial growth of C₆₀ thin films on graphite is predominantly two-dimensional with a high degree of interlayer transport. Specifically, the simulation gives a probability of 0.88 ± 0.10 for a C₆₀ molecule to cross an overlayer descending step.