Image states on Co(0001) and Fe(110) probed by two-photon photoemission

Up to three members of the Rydberg series of image states are observed on Co(0001) and Fe(110) surfaces using high-resolution, two-photon photoemission. Their binding energies and widths are determined. The first image state becomes broader when going from Ni to Co to Fe. The lack of an observable splitting provides an upper limit for a possible magnetic splitting. © 1992 The American Physical Society.