Conduction-band structure of graphite single crystals studied by angle-resolved inverse photoemission and target-current spectroscopy

We have measured the conduction-band structure of single-crystalline graphite by angle-resolved inverse photoemission spectroscopy (ARIPES) and target-current spectroscopy (TCS) up to 38.5 eV above the Fermi level. As opposed to azimuthally disordered pyrolytic graphite we find distinct differences in the ARIPES spectra between the ΓAHK and ΓALM planes of the Brillouin zone regarding intensity and energy location of the observed structures. Such differences are much less pronounced in the TCS spectra. The interpretation of a state at the Γ point near 5 eV above $E_F$ is discussed in terms of an image-potential state or a bulk-band-derived surface state. The experimental band structure is compared with recent band-structure calculations.