The 5f spectral weights in the heavy-fermion alloy system ${\mathrm{U}}_{\mathrm{x}}$${\mathrm{Y}}_{1\mathrm{-}\mathrm{x}}$${\mathrm{Al}}_2$ (x=0.1,0.02) have been measured by resonant photoemission. The major features of the spectra of the dilute systems are identical to those for x=1, showing that single-site effects dominate the large–energy-scale features of the spectrum even in the concentrated system.

• Received 6 March 1987

DOI:https://doi.org/10.1103/PhysRevLett.59.493