Narrow UV photoemission lines from graphite

Stimulated by the recent observation by LEED that well ordered graphite overlayers may be prepared by heating SiC crystals [1] we have used LEED, STM and UPS (hv = 20-140 eV) to study such layers and compared the photoemission spectra to those we obtain from a natural single crystal. Two results are of particular interest. One is that the overlayers give spectra having a quality well on par with those from the natural crystal. This means that the overlayers can be attractive as an alternative to natural crystals, which are inconveniently small for many experiments. The other result is that there are graphite states, which give quite narrow emission lines. One is due to the upper σ state at Γ and another to states near the Fermi level, which for graphite means states at the zone corners. Both lines should be useful for ador absorption studies as an alternative to the C 1s core line and the σ line may provide testing ground for the current modeling of excitation lifetimes in graphite.