APPLICABILITY OF THE SINGLE IMPURITY MODEL TO PHOTOEMISSION SPECTROSCOPY OF HEAVY-FERMION CE COMPOUNDS

Photoemission spectra measured with an energy resolution of 5 meV from Ce-based heavy fermion materials are presented. The spectra add stron g support to the interpretation of the peak at the Fermi level in term s of the spectral function calculated within the single impurity model . This work clearly demonstrates that if reliable information on heavy fermion compounds is to be obtained using photoemission spectroscopy, it is necessary to work with an instrumental resolution approaching k T(K), where T-K is the Kondo temperature.