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

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 degrees 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 CHn 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.