TEMPERATURE-INVARIANT PHOTOELECTRON-SPECTRA IN CERIUM HEAVY-FERMION COMPOUNDS - INCONSISTENCIES WITH THE KONDO MODEL

4f levels in Ce heavy-fermion compounds are examined using resonant photoemission. We find the following inconsistencies with the predictions of the Kondo model: (a) All temperature dependence can be accounted for simply by phonon broadening and the Fermi function; (b) the spectral weights of the features near E(F) do not scale with T(K); and (c) the line shape of the feature previously identified as the Kondo resonance is Lorentzian and about an order of magnitude broader than predictions. Instrument resolution is not a limiting factor.