Solid C58 films

Abstract

A new solid material has been created in ultra high vacuum by utilizing the aggregation process of C₅₈ molecules deposited onto highly oriented pyrolytic graphite from a mass selected low-energy ion beam comprising C₅₈⁺. Cluster fluxes of up to 3 × 10¹¹ ions s⁻¹ cm⁻² with impinging kinetic energies of 6 ± 0.5 eV were typically applied. Growth of the solid C₅₈ phase proceeds according to the cluster-aggregation-based Volmer–Weber scenario where initially ramified 2D islands transform into 3D pyramid-like structures at higher coverages. The C₅₈ films created exhibit much higher thermal stability than the C₆₀ solid phase. Sublimation of C₅₈ sets in at a temperature of 700 K. Ultraviolet photoionization spectra (He I, 21.2 eV) yield a molecular ionization potential in the range between 6.6 and 7 eV. Density functional and Hartree–Fock theories suggest that the formation of C₅₈ dimers and higher multimers upon deposition/aggregation gives rise to the high thermal stability and unique electronic properties of this material.