• Bahn, Emanuel

Abstract

An exact description of the interactions in aromatic carbon systems is a key condition for the design of carbon based nanomaterials. In this paper we investigate the binding and adsorbate structure of the simplest prototype system in this class - the single aromatic ring molecule benzene on graphite. We have collected neutron diffraction data of the ordered phase of deuterated benzene{,} C6D6{,} adsorbed on the graphite (0001) basal plane surface. We examined relative coverages from 0.15 up to 1.3 monolayers (ML) in a temperature range of 80 to 250 K. The results confirm the flat lying commensurate monolayer with lattice constants a = b = 6.5 A at coverages of less than 1 ML. For this structure we observe a progressive melting well below the desorption temperature. At higher coverages we do neither observe an ordered second layer nor a densification of the structure by upright tilting of first layer molecules{,} as generally assumed up to now. Instead{,} we see the formation of clusters with a bulk crystalline structure for coverages only weakly exceeding 1 ML.

Topics

• impedance spectroscopy
• surface
• cluster
• Carbon
• laser emission spectroscopy
• neutron diffraction
• densification
• ordered phase