X-ray absorption and photoemission spectroscopy of bulk insulating materials using graphene

摘要

The charging effect often complicates photoemission spectroscopy and x-ray absorption spectroscopy of an insulating material. Here, mono-layer graphene was used as a conductive layer to prevent the charging effect of insulating substrates such as glass and LiNbO_3. Charging-free spectra were obtained with various photon energies ranging from vacuum ultraviolet light to hard x-rays. This method could also be applied to photoemission spectroscopy of epoxy adhesives and to photoemission electron microscopy of an insulating film. Photoelectron transmis-sivities for the transferred graphene film were evaluated over a wide kinetic energy range from 29 to 7910 eV. A minimum transmissivity of ～0.1 was found at a kinetic energy of ～60 eV, which rose to 0.86 at 7910 eV. In terms of the kinetic energy dependence of the transmissivity, this method is especially suitable for conventional and hard x-ray photoelectron spectroscopy.