Observation of aΛ1-Symmetry Surface State on Ni(111)

An $s-p$—like intrinsic surface state on Ni(111) has been found which has an energy of $E_i=-0.25\mathrm{}$ eV relative to the Fermi energy at $\overline{\Gamma }$ and lies between the $L_3$ ($E_i\simeq -0.15\mathrm{}$ eV) and ${L_2}^{\prime }$ ($E_i=-0.9\mathrm{}$ eV) bulk states. Its momentum dispersion ($E$ vs ${\overrightarrow{\mathrm{k}}}_{\parallel }$) and $h\nu$-dependent photoionization cross section have been determined using angle-resolved photoemission with synchrotron radiation. The existence of this state significantly affects spin-polarized photoemission, chemisorption, band-structure, and exchange-splitting interpretations for Ni.