Surface core-level shifts and surface states for the heavy lanthanide metals

We report on a systematic study of surface core-level shifts of 4f photoemission lines for the close-packed surfaces of monocrystalline films of the heavy lanthanide metals and for the (110) surface of Eu metal. Data are presented for Eu, Dy, Ho, Er, and Lu metal. Surface states close to the Fermi level were observed for all close-packed surfaces studied so far. The magnitudes of the surface core-level shifts were found to be distinctively smaller than previously reported results.