Study of 5d6s valence band and 4f states for metal Sm by synchrotron radiation photoelectron spectroscopy

We have measured the photoemission spectra of Sm film prepared in ultra-high vacuum chamber with synchrotron radiation from 19.4 eV to 178.1 eV. In low photon energy region (hυ < 35 eV), the occupied 5d6s band was clearly observed, which distributes between the Fermi level and ∼2.5 eV binding energy. At higher photon energies, the 4f photoemission exhibits the well-known final-state multiplets of both surface Sm²⁺ and bulk Sm³⁺. However, the photoemission of the surface Sm²⁺ is accompanied by a shoulder crossing the Fermi level. We argue that the shoulder originates from the partial itinerant 4f electrons of the bulk Sm³⁺.