Soft X-ray absorption and emission spectra of nanographene prepared from pentacene with hot mesh deposition and soft X-ray irradiation

Abstract

The molecular orientation and partial density of states were evaluated using NewSUBARU by soft X-ray absorption spectroscopy (XAS) and soft X-ray emission spectroscopy measurements. The degree of molecular alignment was degraded by increasing mesh temperature in hot mesh deposition (HMD), in other words, was changed from pentacene (Pn) to 6,13-dihydropentacene (DHP). At a mesh temperature of 1450 °C, the different XAS was obtained due to the mixing effect of Pn and DHP, and presence of Pn oligomer. The HMD carbon film transformed into the graphite-like film and the graphene on the quartz substrate and the Ni/quartz substrate after soft X-ray irradiation, respectively. The HMD carbon film after soft X-ray irradiation showed the peaks due to terminal carbon such as CH n and COOH in comparison with the reported large graphene sheet. It indicates that the flake size of the graphene on the Ni/quartz substrate was small and had many edges.