C58 on HOPG: Soft-landing adsorption and thermal desorption

Abstract

Electron-impact induced dissociation/ionization of C₆₀ molecules was used to produce an intense beam of C₅₈⁺ ions. This was directed towards a HOPG (highly oriented pyrolytic graphite) substrate under nominally perpendicular impact conditions in order to generate deposits by soft-landing (kinetic energy < 0.1 eV atom⁻¹). Deposited C₅₈ molecules could subsequently be thermally desorbed intactly. Thermal desorption mass spectra of the deposits exhibit only C₅₈. Surface deposited C₅₈ can react with background gases to generate hydride derivatives C₅₈H_n which are also desorbable. The apparent desorption energy of C₅₈ and C₅₈H_n molecules from the HOPG surface varies with increasing adsorbate coverage from 2 ± 0.1 to 2.2 ± 0.1 eV as determined by a Redhead analysis. These values are 0.7 ± 0.1 eV larger than found for C₆₀ desorbed from the same substrate.