Excited Multiplet Lines in Resonant Photoemission Spectra of Gd

Resonant photoemission spectra of Gd metal in the photon energy range of the $4d\to 4f$ excitation show previously unobserved $4f$ multiplet structures. These structures are identified as excited quintet lines by a comparison of a calculation in the fractional parentage scheme with the experimental curve, yielding excellent agreement. Our result provides new insight into the resonance interaction; it also implies an explanation of an unidentified resonance structure in SmS.