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.

Coupled Experimental–Theoretical Characterization of a Carbon Electrode in Vanadium Redox Flow Batteries using X-ray Absorption Spectroscopy

“…However, acid treatment shows a pronounced effectthe spectral feature intensifies to such an extent that the π* and σ* become nearly indiscernible and it expands across a broad energy range of about 3 eV (286.7–289.6 eV). The carbon K edge NEXAFS of the acid-treated sample highly resembles that of a 6, 13-dihydropentacene (DHP) film prepared via hot mesh deposition as documented in . In , a strong feature at 288.4 eV was attributed to the COOH group, a product of DHP oxidation in air, and a shoulder at 287.5 eV was assigned as aliphatic chain resulting from DHP hydrogenation.…”

“…The carbon K edge NEXAFS of the acid-treated sample highly resembles that of a 6, 13-dihydropentacene (DHP) film prepared via hot mesh deposition as documented in . In , a strong feature at 288.4 eV was attributed to the COOH group, a product of DHP oxidation in air, and a shoulder at 287.5 eV was assigned as aliphatic chain resulting from DHP hydrogenation. For the acid-treated electrode investigated in the current work, the sp 2 -bonded COOH is still the most probable functionality given the characteristic peak position at 288.3 eV, but considering that the spectral features of all relevant functional groups presented in untreated carbon electrodes, i.e., sp 2 -bonded CHO, CH 3 , may all overlap with the π* resonance, it is inconclusive to rationalize which functional group dominates the edge functionality of acid-treated carbon electrodes.…”

X-Ray Lithography for Nanofabrication: Is There a Future?

“…Heya et al (Heya et al, 2020, Heya et al, 2021) irradiated pentacene to obtain nanographene. Evlyukhin et al (Evlyukhin et al, 2018) reported the combination of high-pressure and X-ray exposure for the synthesis of oxalates.…”