4<i>f</i>-derived electronic structure at the surface and in the bulk of α-Ce metal

Abstract

Resonant photoemission experiments at the $4\stackrel{\ensuremath{\rightarrow}}{d}4f$ absorption threshold of \ensuremath{\alpha}-Ce are reported. Separation of spectral bulk and surface contributions is achieved by quenching the Ce-derived surface emission with a Dy overlayer. As in previous works, the outermost surface layer of \ensuremath{\alpha}-Ce is found to be \ensuremath{\gamma}-like. In contrast to theoretical predictions, however, the $``{4f}^{0}$ final-state'' signal of the surface is shifted to higher binding energy with respect to \ensuremath{\alpha}-Ce and \ensuremath{\gamma}-Ce bulk emissions. The data are analyzed in the framework of the single-impurity Anderson model. Taking into account the influence of the autoionization channel to resonance process, a larger $4f$ hybridization is concluded than assuming solely a direct photoemission event.