Solid C-58 films

A new solid material has been created in ultra high vacuum by utilizing the aggregation process of C-58 molecules deposited onto highly oriented pyrolytic graphite from a mass selected low- energy ion beam comprising C-58(+). Cluster. fluxes of up to 3 x 10(11) ions s(-1) cm(-2) with impinging kinetic energies of 6 +/- 0.5 eV were typically applied. Growth of the solid C-58 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 C-58. films created exhibit much higher thermal stability than the C-60 solid phase. Sublimation of C-58 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 C-58 dimers and higher multimers upon deposition/ aggregation gives rise to the high thermal stability and unique electronic properties of this material.